Autism spectrum disorder (ASD) and Attention-deficit/hyperactivity disorder (ADHD) are often comorbid. The purpose of this study is to explore the relationships between ASD and ADHD symptoms by applying causal modeling. We used a large phenotypic data set of 417 children with ASD and/or ADHD, 562 affected and unaffected siblings, and 414 controls, to infer a structural equation model using a causal discovery algorithm. Three distinct pathways between ASD and ADHD were identified: (1) from impulsivity to difficulties with understanding social information, (2) from hyperactivity to stereotypic, repetitive behavior, (3) a pairwise pathway between inattention, difficulties with understanding social information, and verbal IQ. These findings may inform future studies on understanding the pathophysiological mechanisms behind the overlap between ASD and ADHD.The online version of this article (doi:10.1007/s10803-017-3083-7) contains supplementary material, which is available to authorized users. Autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) are regarded as distinct disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). ASD symptoms include impairments in interaction, communication and restricted, stereotyped, and repetitive behavior, whereas ADHD is characterized by symptoms of inattention and hyperactivity/impulsivity  or due to an indirect association mediated via another trait (indirect paths). For example, the finding that social problems were only moderately correlated with hyperactivity, yet strongly correlated with inattention , using the Bayesian Constraint-based Causal Discovery (BCCD) algorithm  including children with ADHD and/or ASD, their siblings and control children. Some generic factors are included in our analysis that are known to be associated with ASD and ADHD, namely age, gender, and IQ  study and the Dutch part of the International Multicenter ADHD Genetics (IMAGE data collected between 2004 and 2008) study , 393 unaffected siblings, and 414 controls. Demographics of the study sample are shown in Supplementary Table S1. A more detailed description of participant selection can be found in papers by Steijn et al. and Oerlemans et al. .Hyperactivity symptoms .Impulsivity symptoms .Current ASD symptoms assessed with four subscales of the parent-reported Child Social Behavior Questionnaire (CSBQ) Difficulties in understanding social information, referred to as social ineptness further in the text Fear of/and resistance to changes Stereotyped, repetitive behavior Intelligence as measured using the Wechsler Intelligence Scale for Children (WISC-III) or the Wechsler Adult Intelligence Scale (WAIS-III), depending on child’s age Wechsler , 2000.Verbal IQ, prorated by subtests Similarities and Vocabulary.Performance IQ, prorated by the subtests Block Design and Picture Completion.raw data ADHD symptoms for our analyses instead of the T-scale score, since T-scale scores are adjusted for the effect of gender and age. BCCD can model the effect of age and gender into account, and so we avoided unwanted ‘double correction’. Moreover, we separated impulsivity and hyperactivity subscales based on item scores, instead of using the ‘standard’ DSM hyperactivity/impulsivity subscale to examine the effect of each specific trait. For ADHD symptoms, scores assessed by parents and teachers were provided. To increase the reliability of the symptom assessment, for each subject we averaged the symptom scores from parent and teacher. The main two reasons for that are: (1) ADHD is diagnosed when several symptoms are prevalent in at least two or more settings, thus many clinicians find that parent and teacher ratings are helpful in the diagnostic process; (2) parent- and teacher ratings are highly correlated , which makes it difficult to compare them independently. Unfortunately, it was not possible to obtain information about ASD symptoms from a second observer, thus ASD symptoms were assessed only based on parents report.In this study we considered the The CSBQ contains items refer directly to the DSM-IV criteria for autistic disorder, but also represent less severe variations of these criteria as well as ASD-associated problem such as executive function problems and disruptive behavior in social settings  , unobserved common cause (“A ↔ B”) or a selection bias (“A − B”). If the direction of an edge between two variables is uncertain it has a circle mark “Running the BCCD algorithm we inferred reliability estimates of the causal relations between variables  and built a graph summarizing these relationships presented in Fig. The general structure of the network matches other studies in the literature: gender influences symptom counts with males having higher scores than females Cantwell ; age infThe inferred network suggests that the ASD traits ‘social ineptness’ and ‘stereotyped, repetitive behaviors’ are directly and differentially associated with ADHD symptoms. Social ineptness is associated with inattention and impulsivity, while stereotyped, repetitive behavior is associated with hyperactivity (but not impulsivity). Our network also shows that verbal IQ is a linking factor between ADHD and ASD, since there is a link from verbal IQ to both ADHD and ASD symptom traits. To get a better understanding of these observed direct associations, we zoom in on each link. The direction of these causal links contains circle marks, indicating uncertainty in the causal directions. For example, a link ‘p = 0.79) , providing strong evidence of a direct association. Mediation analysis confirmed that there was no direct link between hyperactivity and social ineptness  Fig. . We provp = 0.11), and impulsivity and repetitive behavior , but an indirect one mediated through social ineptness, which may explain the correlations observed between these variables .Another direct association between ASD and ADHD traits can be seen between hyperactivity and stereotyped, repetitive behaviors (reliability for direct link >99%). No direct causal links are found between repetitive behavior and inattention or impulsivity Fig. . Mediatip = 0.74) and hyperactivity  and that this is mediated through inattention . Mediation analysis also revealed that there is no direct link between verbal IQ and repetitive behavior , reduced contact , and fear of change , but that these effects are mediated through social ineptness and hyperactivity .Our analyses also indicated that inattention and social ineptness are associated via verbal IQ due to direct links between inattention and IQ (reliability for direct link >79%), and between social ineptness and IQ (reliability for direct link >99%). Taking into account the link between inattention and social ineptness mentioned before, all three variables are pairwise connected, which can be a sign of an unobserved common cause for these variables. Mediation analysis showed that verbal IQ is only indirectly associated with impulsivity . Moreover, our model indicates that impulsivity may have a causative effect on social ineptness (and not visa-versa) with reliability >85%. This direction is inferred from (1) the assumption that impulsivity does not cause age, and (2) the dependency between age and social ineptness became insignificant when controlling for impulsivity .Our model makes preliminary predictions about the directions of the causal links between ASD and ADHD traits. According to the model, hyperactivity may have a causative effect on repetitive behavior, with reliability of the link direction >91%. The direction of this link is inferred from (1) the assumption that hyperactivity does not cause age, and (2) the dependency between age and stereotypic behavior became insignificant when controlling for hyperactivity  a pathway from impulsivity to social ineptness, and (b) a pathway from hyperactivity to stereotyped behavior (c) a cluster of inattention, social ineptness and verbal IQ, with a possible common cause.Our findings suggest that there are multiple distinct pathways and causes for the co-occurrence between ASD and ADHD. The strongest link was found between social communication difficulties, inattention and impulsivity. This corroborates previous reports based on both cross-sectional  predictions on the causal direction between inattention and social ineptness. It does put inattention and social ineptness in one cluster with verbal IQ, which can be an indication of an unobserved common cause between these variables, for example a shared genetic factor. Verbal IQ refers to the capacity to use language in order to express oneself, comprehend stories, and understand other people, but also to self-directed speech that supports self-control. Previous studies have reported on language problems in both ASD and ADHD  suggest that interventions that decrease inattention/impulsivity related difficulties are also likely to have a beneficial effect on social functioning, but not the other way around; interventions that affect social functioning cannot be expected to also have a positive effect on the level of inattention/impulsivity. The same logic is applicable for the effect of hyperactivity on repetitive behavior. These findings are consistent with results from longitudinal study by St. Pourcain et al. . They shSeveral strengths and limitations should be taken into account when assessing the results of the current study. The main strength of this study is the application of a novel causal discovery method for data analysis. This method considers all variables together, infers both direct and indirect dependencies between variables, provides a reliability measure for each edge in the network, and is able to detect latent common causes. This method does not require longitudinal or interventional data and can infer causal statements based on cross-sectional data Pearl . AnotherIn conclusion, our results indicate that the often reported co-occurrence of ASD and ADHD might be explained by three distinct pathways: (a) between inattention/impulsivity and social ineptness, and (b) between hyperactivity and stereotypic, repetitive behaviors (c) through verbal IQ. These findings may inform future studies on understanding the  mechanisms behind the overlap between ASD and ADHD.Below is the link to the electronic supplementary material.Supplementary material 1 (DOCX 17 KB)Supplementary material 2 (DOCX 267 KB)


Dispersion of carbon nanotubes (CNTs) is a challenge for their application in the resulting matrixes. The present study conducted a comparison investigation of the effect of four surfactants: Alkylphenol polyoxyethylene ether (APEO), Silane modified polycarboxylate (Silane-PCE), I-Cationic polycarboxylate (I-C-PCE), and II-Cationic polycarboxylate (II-C-PCE) on the dispersion of hydroxyl functionalized multi-walled carbon nanotubes (MWCNTs–OH). Among the four surfactants, APEO and II-C-PCE provide the best and the worst dispersion effect of CNTs in water, respectively. Dispersion effect of MWCNTs–OH has been characterized by optical microscope (OM), field emission-scanning electron microscope (FE-SEM), and Ultraviolet–visible spectroscopy (UV–Vis).The OM images are well consistent with the UV–Vis results. Based on the chemical molecular structures of the four surfactants, the mechanism of MWCNTs–OH dispersion in water was investigated. For each kind of surfactant, an optimum surfactant/MWCNTs–OH ratio has been determined. This ratio showed a significant influence on the dispersion of MWCNTs–OH. Surfactant concentration higher or lower than this value can weaken the dispersion quality of MWCNTs–OH. Carbon Nanotubes (CNTs) are regarded as a one-dimensional carbon nanomaterial. According to the layer number, they are classified as either single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). CNTs can be defined as rolled up from a single planar sheet of graphene, in the case of SWCNTs, and multi planar sheets in MWCNTs. Since the CNTs were discovered occasionally by Iijima in 1991 , electriCNTs are extremely hydrophobic, and due to the delocalization of π–electrons, CNTs exhibit very significant conductivity, besides, the adsorption between CNTs and different chemical moieties are also enhanced . In addi3/H2SO4, ozone, etc. to improve the solubility of CNTs in solvents. Nevertheless, an aggressive chemical functionalization creates defects on the surface of CNTs and, consequently, an alteration in the CNTs properties [Mechanical methods and chemical approaches are most widely used in dispersing CNT agglomerations. Mechanical methods, like ultra-sonication, high shear mixing, and ball milling are usually used to shorten CNTs lengths by inputting high energy or direct mechanical contact ,16. Amonoperties . A non-coperties .Through non-covalent adsorption on CNTs surfaces, surfactants (SAA) enable the CNTs to preserve the dispersing state for a long period in aqueous solutions, therefore altering the environmental behavior and utilization of CNTs. To date, the CNT dispersibility of various surfactants and corresponding acting mechanisms have been investigated by a variety of researches {I.E. Octyl-phenol-ethoxylate (Triton X-100) , SodiumdThis study has carried out a comparative analysis of MWCNTs–OH dispersion by four different surfactants: Alkylphenol polyoxyethylene ether (APEO), Silane modified polycarboxylate (Silane-PCE), I-Cationic polycarboxylate (I-C-PCE) and II-Cationic polycarboxylate (II-C-PCE). All selected surfactants in this research are superplasticizers for cement. Therefore, the study results can be utilized for further studies on CNTs modified cement based composites. Due to the hydroxyl (–OH) of MWCNTs–OH can form chemical bonds with cement hydration production, therefore, MWCNTs–OH rather than pristine MWCNTs was used in this study. The dispersing abilities of the surfactants have been studied experimentally and theoretically, assuming of their chemical structure. The experimental results provide insight into some of the parameters for further optimization of MWCNTs–OH dispersion using surfactants. Visual observation and UV–Vis spectroscopy have been applied to analyze the dispersibility of each surfactant. Through this study, the importance of employing a certain ratio of surfactant and MWCNTs–OH can be established, in order to obtain an optimum dispersion.MWCNTs with –OH functional group were purchased from Chengdu Organic Chemicals Co., Ltd., Chengdu, China, Chinese Academy of Sciences. It was produced by a chemical vapor deposition (CVD) device. An acid treatment was introduced to purify the raw MWCNTS–OH, as according to the manufacturer. Acid oxidation has been washed away before the CNTs were released. The main physical properties of MWCNTs–OH are shown in In order to compare the dispersing capacity of the four surfactants and establish the optimal CNT to surfactant ratio for each surfactant, dispersions of surfactants were prepared at concentrations spanning from 0.1 to 14 g/L, according to the category of surfactant and keeping the concentration of MWCNTs–OH (1 g/L) constant. The MWCNTs–OH and surfactant were mixed previously with 100 mL of de-ionized water into a flask and stirred for 15 min. Then, the dissolution was performed with an ultrasonication treatment with a 650 W ultrasonic cell crusher , set to amplitude of 30% and in 4 s cycles, for the sake of protecting the mixture from being over-heated. The whole ultrasonication time was 30 min. After the ultrasonication had finished, the dispersion of MWCNTs–OH were diluted 100 times and measured by visual observation and UV–Vis spectrometry. In the UV–Vis measurement, each sample was measured three times and the average absorbance values, at 600 nm of the UV–Vis spectrum, were used for following comparison. The identification of the phase, present in the raw materials was made by X-ray diffraction (XRD), using a Brucker D8 ADVANCE equipment  in a 2θ interval between 10° and 70°, with a steps of 0.02°. Morphology of the as-received carbon nanotubes was examined using Hitachi Su-70 field emission-scanning electron microscope  at an accelerating voltage of 20.0 kV, the MWCNTs–OH were sprayed with gold before observation. Fourier Transform Infrared Spectrometer (FT-IR) experiments were conducted to identify the functional groups on the surface of MWCNTs–OH and the four surfactants. The FT-IR model used was a Nicolet Nexus670 Fourier Transform Infrared Spectrometer , in transmission mode with KBr pellets.Suspensions containing a well-known ratio of MWCNTs–OH and surfactant samples were prepared by ultrasioncation of MWCNTs–OH in an aqueous solution with the different surfactants selected. After the ultrasonication process, a pipette tip was carefully used to suck up 0.5 mL of the suspension and dipped it in a glass vial, which contained 100 mL of deionized water. The morphologies of the suspensions were directly examined by naked-eye observation.After the macroscopic observation, microscopic views of the dispersing state of MWCNTs–OH with different surfactants were obtained by conducting analyses on Hitachi Su-70 field emission-scanning electron microscope (FE-SEM) . Samples were prepared by drop coating MWCNTs–OH solutions on a clean side glass and drying at 50 °C in an oven, followed by the coating of a thin layer of gold before observation.Later the microscopic observation, the dispersion of MWCNTs–OH produced by the different surfactants, was measured by UV–Vis spectrometry. A PerkinElmer Lambda 750 spectrophotometer  with a wavelength range from 190 to 1100 nm was used. During the experiment, pure solutions of the four surfactants were measured as baseline correction to the substrate, their absorbance values from that of MWCNTs–OH dispersions.SEM was employed to study the morphology of the MWCNTs–OH before ultrasonication treatment. The SEM photograph  showed t−1 was found in the five curves, which is commonly attributed to the –OH stretching [−1 is largely assigned to the symmetrical stretching vibration mode of –CH– [−1 [−1 is strongly related to the –CH2–  [−1 in the FT-IR spectrum of MWCNTs–OH, and the peak around 1640 cm−1 in the FT-IR spectra of four surfactants correspond to –C=O– stretching vibration [−1, represents the C–O stretching vibration [−1 in curve (b) is due to the nature C–C stretching of benzene ring. At curve (c) and curve (d), the strong peak at 950 cm−1 is associated with C–N vibration [−1 and 840 cm−1 are assigned to the Si–O and Si–C stretching vibration [The feature of the functionalized groups in MWCNTs–OH and four surfactants were both confirmed by FT-IR spectroscopy. The FT-IR spectra of raw MWCNTs–OH and surfactants are demonstrated in retching . The str of –CH– ,29. The –CH– [−1 . Peak apbending) . The shaibration ,32,33. Aibration . The shaibration . In the ibration , respectThe FT-IR spectra suggested that the MWCNTs used in this experiment were hydroxyl functionalized and there were carboxyl functionalized groups on their surfaces. It is because when the fresh MWCNTs were acid treated to remove the catalyst particles, the carbon atoms on defective sites, or the tips of the tube, were oxidized into carboxyl (–COOH) . The funXRD measurement was carried out to identify the crystalline phases present in the raw materials. As it can be seen from the XRD result , the strThe ideal dispersion will support the most MWCNTs–OH and exhibit acceptable stability with the lowest amount of surfactant used.Images taken for visual observation are shown in In the UV–Vis spectra, individual MWCNTs–OH can be identified by the π–π transition of the –C=C–, which shows a strong peak at 270 nm ,38. CNT The above observed differencesin dispersibility among the four surfactants can also be illustrated by their chemical structure, as shown in It is known, as it can be checked in When we have compared I-C-PCE with II-C-PCE, in terms of dispersing ability, I-C-PCE shows a greater dispersing potential, due to the mentioned “hydrophilic chain length factor”, which is the same in the APEO surfactant. As a result, for a surfactant with a shorter hydrophilic chain length, it is less possible to form a micelle that is caused by an interaction between the side chains of the neighboring surfactant molecular, which would cause a depletion reduction effect, and consequently, lead to the re-agglomeration of MWCNTs–OH in an aqueous solution . Therefo3)3 at the end of the side chains while II-C-PCE has a N–(CH3)3 group in the same position. According to Fan’s research [The chemical molecular structure of Silane-PCE and II-C-PCE is similar, with the same hydrophilic chain length in their branches. The most characteristic difference between the two surfactants is the head group in the side chains. Silane-PCE has trialkoxysilane groups Si–(OCHresearch , trialkoIn this study, comparative experiments have been conducted to study the difference in the dispersing capacities of four surfactants, namely APEO, Silane-PCE, I-C-PCE, and II-C-PCE. The main task of this research was to study the factors that are responsible for the dispersing capacities of the four surfactants, as well as the difference between them. With this key idea, visual observations and UV–Vis studies of MWCNTs–OH dispersion in above surfactant solutions were executed. The experimental results have indicated that the dispersing ability shows the following trend: APEO > I-C-PCE > Silane-PCE > II-C-PCE. This tendency was further checked according to the characteristics of chemical molecular structures of the four surfactants. The experimental investigation was consistent with the results of some researches, which suggest that APEO benefits come from its benzene ring, when it intents to disperse MWCNTs–OH in aqueous solution. Besides, another finding enables us to make the conclusion that the “hydrophilic chain length factor” contributes more to MWCNTs–OH dispersion in comparison to the “siloxane group factor”. Thus, the chemical molecular structure of a surfactant has a great impact on its dispersing ability. The main purpose of this research is the obtaining of the optimum surfactant/MWCNTs–OH ratio. This ratio has great significance, due to the quality of MWCNTs–OH suspensions deteriorating when this ratio was lower or higher than the optimum value. Thereby, in order to avoid any excess that would decrease the quality of MWCNTs–OH dispersion, the surfactant concentration should be controlled to be just sufficient to coat the MWCNTs–OH surface. It was found, in our study, that nanotube dispersions obtained the best quality when the surfactant/MWCNTs–OH ratio for APEO, I-C-PCE, Silane-PCE, and II-C-PCE was 0.2:1, 2:1, 12:1, and 4:1, respectively. In conclusion, when choosing a surfactant to disperse MWCNTs–OH in aqueous solution, factors like chemical molecular structure and the ratio of surfactant/MWCNTs–OH ratio should be taken into consideration.


Bartonella includes fastidious, facultative intracellular bacteria mainly transmitted by arthropods and distributed among mammalian reservoirs. Bartonella spp. implicated as etiological agents of zoonoses are increasing. Apart from the classical Bartonella henselae, B. bacilliformis or B. quintana, other species  have also been associated with human and/or animal diseases. Laboratory techniques for diagnosis  usually show lack of sensitivity. Since 2005, a method based on a liquid enrichment Bartonella alphaproteobacteria growth medium (BAPGM) followed by PCRs for the amplification of Bartonella spp. has been developed. We aimed to assess culture, molecular and serological prevalence of Bartonella infections in companion animal veterinary personnel from Spain.The genus B. vinsonii berkhoffii , B. henselae, B. quintana and B. koehlerae as antigens were performed. A cut-off of 1:64 was selected as a seroreactivity titer. Blood samples were inoculated into BAPGM and subcultured onto blood agar plates. Bartonella spp. was detected using conventional and quantitative real-time PCR assays and DNA sequencing.Each of 89 participants completed a questionnaire. Immunofluorescence assays (IFA) using Bartonella spp. or genotypes, the lowest seroreactivity was found against B. quintana (11.2%) and the highest, against B. v. berkhoffii genotype III (56%). A total of 27% of 89 individuals were not seroreactive to any test antigen. Bartonella spp. IFA seroreactivity was not associated with any clinical sign or symptom. DNA from Bartonella spp., including B. henselae (n = 2), B. v. berkhoffii genotypes I (n = 1) and III (n = 2), and B. quintana (n = 2) was detected in 7/89 veterinary personnel. PCR and DNA sequencing findings were not associated with clinical signs or symptoms. No co-infections were observed. One of the two B. henselae PCR-positive individuals was IFA seronegative to all tested antigens whereas the other one was not B. henselae seroreactive. The remaining PCR-positive individuals were seroreactive to multiple Bartonella spp. antigens.Among antigens corresponding to six Bartonella spp. were found in companion animal veterinary personnel from Spain. More studies using BAPGM enrichment blood culture and PCR are needed to clarify the finding of Bartonella PCR-positive individuals lacking clinical symptoms.High serological and molecular prevalences of exposure to, or infection with, The online version of this article (10.1186/s13071-017-2483-z) contains supplementary material, which is available to authorized users. Bartonella spp. are fastidious, facultative intracellular, pleomorphic Gram-negative bacilli included in the class Alphaproteobacteria with at least 35 validated species and three subspecies (http://www.bacterio.net/bartonella.html). A wide range of animals are hosts and reservoirs of Bartonella spp., mainly transmitted by feces of fleas and lice, and bites of sand flies and potentially ticks [ly ticks .Bartonella species and subspecies should be considered potentially zoonotic. An increasing number of Bartonella spp. has been associated with an expanding clinical spectrum in humans and animals [Bartonella bacilliformis  are confined to the highlands of Peru, Colombia and Ecuador, as the Lutzomyia sand fly vector is geographically limited. Bartonella quintana, responsible for trench fever during the first and second World Wars, has reemerged in homeless and alcoholic people with poor hygiene (e.g. refugee camps). B. quintana is also a known cause of bacillary angiomatosis and peliosis hepatis in HIV patients, chronic lymphadenopathy in immunocompromised or immunocompetent patients, and blood culture negative (BCN) endocarditis [Although not yet demonstrated, all  animals –3. Some carditis .Bartonella henselae, the main agent of cat scratch disease (CSD) was described [B. henselae has become the most representative species of the genus and the one most frequently reported as a human or animal pathogen [Bartonella henselae is one of the main causes of subacute and chronic lymphadenopathy in children and young people, and also causes other severe infections such as endocarditis, hepatosplenic abscesses, retinopathy, uveitis, peliosis hepatis and bacillary angiomatosis, among others [Bartonella spp. such as B. elizabethae, B. vinsonii (subsp. berkhoffii and subsp. arupensis), B. koehlerae and B. alsatica have been implicated in endocarditis cases; B. rochalimae has been associated with fever and bacteremia; B. tamiae, with febrile illness; and B. grahamii, with neuroretinitis [Bartonella infections are considered emerging and re-emerging infections in humans.In 1992, a new bacterium, escribed . Subsequg others . Other Betinitis . For allBartonella spp. can grow in axenic media, the sensitivity of culture is usually very low. In recent decades molecular tools have been used diagnostically in clinical practice to test certain samples such as adenopathies or cardiac valves for fastidious organisms. However, these techniques are not routinely available, and serological tests are usually the diagnostic modality offered by microbiological laboratories, although cross reactivity between Bartonella spp. may occur [Bartonella infections has been used for the study of animal and human diagnostic specimens. It is based on an enrichment growth medium for Bartonella culture that improves the yield of Bartonella spp. detection by subsequent molecular biology techniques (PCR and DNA sequencing), and it is called the Bartonella alpha-proteobacteria growth medium (BAPGM) enrichment blood culture/PCR platform [Although ay occur . Since 2platform , 9.Bartonella spp. infections in a group considered at risk  due to frequent exposure to pets and their associated arthropods.We aimed to investigate culture, molecular and serological prevalence of Bartonella spp./subspecies) and bacteremia using enrichment blood culture, PCR and DNA sequencing in companion animal veterinary personnel.A cross-sectional study was performed to determine the seroprevalence  was recorded. Persistent/chronic disease was defined in the questionnaire as longer than six months.Approximately 10–12 ml of blood  was collected at the time of enrollment. Aseptic technique was used including chlorhexidine decontamination of the skin. An experienced nurse performed venipuncture.Refrigerated EDTA-anticoagulated blood and serum samples were transported in less than 48 h by car to the Center of Rickettsiosis and Arthropod-Borne Diseases at CIBIR , where blood was centrifuged and sera stored to -80 °C until being prepared for shipping to Galaxy Diagnostics, Inc., Research Triangle Park, North Carolina, USA.Bartonella v. berkhoffii, B. henselae, and B. koehlerae antibodies were determined in the Intracellular Pathogens Research Laboratory (IPRL) at North Caroline State University  using cell culture grown bacteria as antigens and following standard immunofluorescent antibody assay (IFA) techniques. Cell lines were determined Mycoplasma free by PCR testing. Canine isolates of B. v. berkhoffii genotype I , B. v. berkhoffii genotype II , and B. v. berkhoffii genotype III (NCSU 06CO-01 Klara) and feline isolates of B. henselae H-1 strain (NCSU 93FO-23 Cisco), B. henselae SA2 strain , and B. koehlerae  colonies were passed from agar plate grown cultures into Bartonella-permissive cell lines, i.e. the DH82 (a canine monocytoid) cell line for strains B. henselae H-1 and SA2, B. v. berkhoffii I and B. koehlerae and Vero cells  for B. v. berkhoffii II and III to obtain antigens for IFA testing. For each antigen, heavily infected cell cultures were spotted onto 30-well Teflon-coated slides (Cel-Line/Thermo Scientific), air-dried, acetone-fixed, and stored frozen. Fluorescein conjugated goat anti-human IgG  was used to detect bacteria within cells using a fluorescent microscope .To compare results across studies, we used culture, serological and enrichment blood culture/PCR techniques in this study, as were used in a previous study involving veterinary personnel . BartoneSerum samples diluted in phosphate-buffered saline (PBS) solution containing normal goat serum, Tween-20, and powdered nonfat dry milk to block nonspecific antigen binding sites were first screened at dilutions of 1:16 to 1:64. All sera that were reactive at a titer of 64 were further tested with two-fold dilutions out to 1:8192. To avoid confusion with possible nonspecific binding found at low dilutions, a cut-off of 1:64 was selected as a seroreactive titer.2, water-saturated atmosphere. After 7, 14, and 21-day incubation periods, a 1-ml aliquot of the enrichment culture was inoculated onto blood agar plates and incubated at 35 °C. Plates were checked for colony formation at 7, 14, and 21 days after inoculation.BAPGM enrichment blood culture/PCR was performed at Galaxy Diagnostics Inc., Research Triangle Park, North Carolina, USA, as previously described , 10, 11.Bartonella spp. PCR [Bartonella spp. moreover, strain classification was performed using primers designed to amplify two consensus sequences in the Bartonella 16S-23S internal transcribed spacer (ITS) region as described previously with minor modifications [TaqMan probe 438  levels by conventional PCR was performed in a 25 μl final volume reaction containing 12.5 μl of MyTaq HS Red Mix 2× (Bioline), 0.2 μl of 100 μM of each forward and reverse primer (IDT-DNA Technology), 7.3 μl of molecular-grade water, and 5 μl of DNA from each sample tested. PCR negative controls were prepared using 5 μl of dH2O (when testing isolates from plates), 5 μl of DNA from the blood of a healthy dog, or 5 μl of DNA extracted from un-inoculated BAPGM-negative controls (when testing BAPGM enrichment cultures). Positive controls for PCR were prepared by serial dilution (using dog blood DNA) of genomic DNA from B. henselae (Houston I strain type) down to 0.001 pg/μl . Conventional PCR was performed in an Eppendorf Mastercycler EP gradient under the following conditions: a single hot-start cycle at 95 °C for 3 min followed by 55 cycles of denaturing at 94 °C for 15 s, annealing at 66 °C for 15 s, and extension at 72 °C for 18 s. Amplification was completed by an additional cycle at 72 °C for 1 min, and products were analyzed by 2% agarose gel electrophoresis with detection using ethidium bromide under ultraviolet light. Amplicon products were sequenced to determine the Bartonella sp. and ITS strain type. Quantitative real-time PCR was also performed in a 25 μl final volume reaction containing 12.5 μl of SsoAdvanced Universal Probes supermix , 0.2 μl of 100 μM of each forward and reverse primer , 0.2 μl of 100 μM of TaqMan probe, and 7.3 μl of molecular-grade water. Positive and negative controls used were as described above. qPCR was performed in a CFX96 Real-time System (Bio-Rad) under the following conditions: a single hot-start cycle at 95 °C for 3 min followed by 44 cycles of denaturing at 94 °C for 10 s, annealing at 66 °C for 10 s, and extension at 72 °C for 10 s. Fluorescence at channel one was detected during the extension cycle. As in conventional PCR, all amplicon products were sequenced to determine the Bartonella sp. and ITS strain type. All PCR and un-inoculated BAPGM enrichment controls remained negative throughout the study period.Using standard operating procedures, DNA was extracted from EDTA anticoagulated blood, enrichment liquid blood culture, and from blood agar plate colony isolates if obtained after subculture of the previously enriched blood samples for spp. PCR . Bartoneications , 12. AmpPCR amplicon sequence analysis was performed using a commercial company . Chromatogram evaluation and sequence alignment were performed using Contig-Express and AlignX software . Bacteria species and strain were defined by comparing similarities with other sequences deposited in the GenBank database using the Basic Local Alignment Search Tool (Blast v. 2.0), and an in-house curated database.Questionnaire data for the study were collected on paper forms, entered into a Microsoft Excel database, and validated comparing the electronic records with the information on the forms. Associations of demographic, risk factor, symptoms and exposure variables were assessed with means and medians for continuous variables, and with counts and percentages in contingency tables for categorical data. Group comparisons were performed. The Fisher's exact test for categorical variables and the Mann-Whitney U-test for numerical variables were used. Data processing was carried out with the R software , versionA total of 89 veterinary personnel from different regions of Spain  were enrolled in the study and a total of 178 samples (EDTA-blood and sera) and the accompanying questionnaires were used to generate data reported in the study. The main characteristics of the study population (exposures and demographics) are listed in Additional file Bartonella spp. or genotypes ranged between 11.2–56.2%, with the lowest percentage reactivity (11.2%) to B. quintana .Among individual study participants, seroreactivity patterns varied among the six ng Table . BartoneP = 0.343). For PCR-positive participants, B. quintana was amplified and sequenced from 14 or 21-day BAPGM enrichment blood cultures (two veterinarians), B. v. berkhoffii genotype I from 7 and 14-day cultures (one veterinarian), B. v. berkhoffii genotype III from blood or a 7-day BAPGM enrichment blood culture (one veterinarian and veterinary technician), and B. henselae from seven and 14 days BAPGM enrichment blood cultures (two veterinarians). Blood agar plate subculture isolates were not obtained from any participant. No individual was found to be co-infected with more than one Bartonella spp. BAPGM enrichment blood culture/PCR positivity was not statistically associated with clinical signs or symptoms  had a positive BAPGM enrichment blood culture/PCR result Table . There wB. henselae PCR-positive individual was IFA seronegative to all test antigens, and another one was not seroreactive to B. henselae. The remaining five PCR-positive individuals were seroreactive to multiple Bartonella spp. antigens  and molecular  prevalence of Bartonella exposure or infection, respectively, in patients without typical clinical presentations or environmental epidemiological exposures is challenging. For example, the diagnosis of CSD in a patient with lymphadenopathy after being bitten or scratched by a mammal (cat or dog) is straightforward and microbiological assays are unnecessary in most instances to confirm the clinical diagnosis. In contrast, syndromes or illnesses caused by Bartonella spp. such as endocarditis, peliosis, angiomatosis, fever of unknown origin, isolated hepatosplenic abscesses, uveitis, and others are clinically challenging, diagnostically problematic, and require microbiological confirmation of diagnosis. In addition, specifically defining the infecting Bartonella sp. as the etiological agent of illness is necessary to determine disease epidemiology and to facilitate disease surveillance among various populations . However, implicating a Bartonella sp. as the causative agent of an atypical clinical presentation can be difficult when using serology, and even if the bacterial DNA is amplified from blood or enrichment blood cultures or if the organism is cultivated from the blood. Recently, B. henselae and B. clarridgeiae have been isolated from the blood of human donors in Brazil using BAPGM enrichment culture/PCR, indicating that asymptomatic bacteremia can occur in healthy humans [B. quintana bacteremia has been reported in homeless and in immunosuppressed patients [Bartonella spp. can induce long standing intra-erythrocytic and endothelial cell infections in healthy individuals without causing pathology or long standing bacteremia may lead to chronic, slowly progressive vascular injury in an otherwise immunocompetent individual [Bartonella serological or molecular microbiological blood culture results in this study and patients without a medically defined clinical syndrome must be cautiously interpreted.Clinically, the diagnostic interpretation of these serological and molecular test results supporting y humans . Moreovepatients . Thus, idividual . Data inBartonella infections is based on serological assays, with current techniques lacking sensitivity, specificity or both. Moreover, conventional cultures (gold standard) are not routinely used due to the overall poor sensitivity in isolating Bartonella spp. In recent years, molecular assays have been used for clinical diagnosis and epidemiological studies in vectors (e.g. fleas) [Bartonella spp. antibodies was found using in-house IFA assays and six different species and genotypes and strains. As veterinary personnel have frequent contact with reservoir hosts  and with Bartonella vectors , it is likely that these individuals are repeatedly exposed to these bacteria throughout their careers. Although cross reactivity occurs when IFA is used, exposure to more than one Bartonella spp. is also possible in veterinary personnel and others with frequent animal and arthropod exposures. For unknown reasons, the highest seroreactivity in the studied population was observed against B. v. berkhoffii genotype II, whereas only genotypes I and III were detected by enrichment blood culture/PCR. Bartonella koehlerae seroprevalence was also high among veterinary personnel (41.6%), although neither culture nor molecular amplification of this species was obtained in this study, despite testing with B. koehlerae-specific PCR primers. The presence of B. koehlerae has been reported from the Americas, Europe, Asia and Australia [B. koehlerae, and this species has been associated with disease in dogs [B. koehlerae was implicated diagnostically in a veterinarian with complex regional pain syndrome type I [In most clinical microbiology laboratories the diagnosis of . fleas) , 17–19. ustralia –25. Cats in dogs –22, with in dogs  and with in dogs . By seroe type I .B. henselae seroprevalence was found in this veterinary worker population (37.1%). This Bartonella has a worldwide distribution, cats are the main reservoirs and vectors, and fleas  are considered the primary arthropod vectors for infecting cats and other animals. B. henselae is the primary or sole causative agent of CSD and induces other clinical syndromes in humans [Bartonella infections is scarce in Spain. Nevertheless, clinical descriptions [B. henselae/B. quintana [B. henselae seroprevalences in cat owners, HIV-infected patients and blood donors were 28.9%, 17.3% and 5.9%, respectively, using a commercial kit [Bartonella spp. moreover, other infectious agents [B. henselae infection, and this species has also been involved in disease in dogs from Spain [C. felis were infected with B. henselae and B. clarridgeiae, respectively [B. henselae and B. clarridgeiae have been isolated from healthy human blood donors in Brazil [Bartonella from the blood of healthy humans in Spain. Although a study from the United States found a statistical association between Bartonella spp. bacteremia and symptomatology [B. henselae bacteremia can be documented in asymptomatic individuals.As expected, a high ation 37.%. This Briptions , 17, 26 quintana –29 have cial kit , 31. Thes agents . Contactom Spain . In a moectively . Importan Brazil . To our matology , that stBartonella spp., whereas PCR amplification and DNA sequence confirmation of bacterial DNA from blood or cultures supports infection at the time of sampling. PCR and DNA sequencing confirmed the infection with B. henselae, B. quintana, and two B. v. berkhoffii genotypes . Four out of seven infected individuals were asymptomatic at the time of sample collection and the remaining three reported historical symptoms such as insomnia, memory problems and fatigue. B. v. berkhoffii genotype III has been recently documented as a cause of endocarditis and myocarditis in dogs [Bartonella v. berkhoffii has been involved in at least one human case of endocarditis [B. henselae and B. v. berkhoffii has also been reported [B. v. berkhoffii, the vector(s) responsible for transmission of this infection are unknown [Serology can only imply that the investigated population has been exposed to one or more  in dogs , and gen in dogs . Bartonecarditis , and it carditis  and rheucarditis . A case reported . Althoug unknown , 43.B. quintana, the agent of trench fever and other diseases. It is known that, outside of the context of HIV, B. quintana has been isolated from afebrile homeless and alcoholic patients from North America and small European clusters [B. quintana acquisition in these two individuals is unresolved, as none of the study subjects recalled exposure to body lice (Pediculus humanus corporis), considered the sole primary vectors of B. quintana. These arthropods are common under poor hygiene conditions, which was not the case of the participants of our study. Apart from body lice, B. quintana DNA has been amplified from cat fleas and bed bugs (Cimex lectularius) [B. quintana endocarditis has been documented in dogs from New Zealand and the United States [B. quintana transmission to a previously healthy, bacteremic human [B. quintana infections since the individuals reported exposure to fleas, head lice (Pediculus humanus capitis) and a variety of animals.Unexpectedly, two asymptomatic veterinarians were enrichment blood culture/PCR-positive to clusters , but to ularius) , 45. B. d States , and bitic human . CollectBartonella spp. evolved as a result of the detection of B. quintana and B. henselae infections in HIV patients with bacillary angiomatosis or peliosis hepatis. Thus, infection in severely immunocompromised individuals was required before the worldwide clinical emergence of the genus Bartonella became recognized. During the ensuing decades, there have been continuous and substantial changes in our understanding of the epidemiology, pathophysiology and vector biology associated with these bacteria.To a substantial degree, the current re-emergence or rediscovery of Bartonella in veterinary personnel. Future research is required to clarify the duration of and potential relationship to Bartonella spp. bacteremia and non-specific symptoms or subtle pathology in immunocompetent individuals.This study documented high serological and molecular prevalence of Additional file 1: Table S1.P-values for the differences between Bartonella PCR-positive and PCR-negative individuals. (DOCX 20 kb)Exposures and demographics of veterinary subjects, tests statistics and Additional file 2: Table S2.Exposures, demographics and clinical features, if any, of bacteremic veterinary personnel based upon BAPGM enrichment blood culture/PCR positivity. (DOCX 17 kb)


The CSAC can achieve a short-term stability of 2.5 × 10−12 s, which implies a range error of 0.075 m, making for an 87.5% improvement over TCXO. Replacing the internal TCXO clock of GNSS receivers with a higher frequency stability clock such as a CSAC oscillator improves the navigation solution in terms of low satellite visibility positioning accuracy, solution availability, signal recovery (holdover), multipath and jamming mitigation and spoofing attack detection. However, CSAC suffers from internal systematic instabilities and errors that should be minimized if optimal performance is desired. Hence, for operating CSAC at its best, the deterministic errors from the CSAC need to be properly modelled. Currently, this modelling is done by determining and predicting the clock frequency stability  within the positioning estimation process. The research presented in this paper aims to go a step further, analysing the correlation between temperature and clock stability noise and the impact of its proper modelling in the holdover recovery time and in the positioning performance. Moreover, it shows the potential of fine clock coasting modelling. With the proposed model, an improvement in vertical positioning precision of around 50% with only three satellites can be achieved. Moreover, an increase in the navigation solution availability is also observed, a reduction of holdover recovery time from dozens of seconds to only a few can be achieved.Chip Scale Atomic Clocks (CSAC) are recently-developed electronic instruments that, when used together with a Global Navigation Satellite Systems (GNSS) receiver, help improve the performance of GNSS navigation solutions in certain conditions . Current GNSS receivers include a Temperature Compensated Cristal Oscillator (TCXO) clock characterized by a short-term stability ( A new generation of atomic clocks, the Chip Scale Atomic Clock (CSAC), are now commercially available. Atomic clocks price, size and power consumption have been reduced considerably in recent years ,2. This The theoretical basis underpinning GNSS is the triangulation of satellite signals whose range is derived by measuring, as precisely as possible, their propagation time. Thus, clocks are the fundamental components of GNSS; they are used to estimate the propagation time, or equivalently, the pseudoranges . Since t−10 s, improving to 10−12 s after 3000 s of GNSS disciplining [A Defense Advanced Research Projects Agency (DARPA) CSAC program was the basis of CSAC technology development . It evoliplining .Once the CSAC is properly disciplined the GNSS receiver can benefit from its accuracy. First, there is an improvement in the correlator’s synchronism, which is attributable to the reduction of the PLL bandwidth. Thus, it helps improve the tracking recovery time (holdover) and the signal to noise ratio (SNR) . In prevPrevious studies with CSAC and GNSS receivers show the contribution of atomic clocks to obtain a navigation solution using only three satellites ,12,13. IHowever, before integrating an atomic clock into a GNSS receiver, it is necessary to characterize it and model its errors. Details about the CSAC internal elements and some results of its prototyping development and their behaviour are public . CSAC osThe main objective of this study is to contribute to the quantification of the benefits of adding a properly modelled CSAC time source to a GNSS receiver. To achieve this objective, the study presented in this paper focus on two complementary purposes. First, it aims to rigorously model CSAC behaviour. To do so, a CSAC clock characterization, calibration (at different temperatures) and aging evaluation were done. The second purpose of the study is to evaluate the impact of the previous characterization and calibration in the terms of track recovery time after outages (holdover), with a properly disciplined CSAC and in terms of position scattering solution, mainly the Vertical Dilution of Precision (VDOP), with a CSAC calibrated by temperature.The paper is therefore organized as follows: first , a briefOscillators produce a periodical signal. Far from oscillating at a constant frequency, they always suffer deviations with respect to their nominal frequency . The perRubidium/Caesium Atomic Clocks—used in satellites;Caesium Chip Scale Atomic Clock (CSAC)—used in some high-grade receivers; andTCXO—used in most of the commercial receivers.In the GNSS context, the following clocks are considered, from high to low performance (in terms of stability):Although with different severity grades, all oscillators suffer from systematic errors coming from environmental effects such as vibrations, shock, radiation, humidity, temperature and aging. Therefore, by determining these systematic errors it is possible to adjust a better clock model and to improve GNSS performance.The Allan variance (AVAR)  is a welIn this study, clock characterization is only based on Allan variance due to our knowledge with this technique, also used to characterize the stochastic noises of inertial sensors (which is another field of work of our research group). Furthermore, the Allan variance is a typical parameter provided by the manufacturers.γ(ι) is the normalized frequency difference between the frequency and the nominal frequency averaged over the measurement interval τ [The Allan variance, terval τ .f is the sampling frequency and 0 (white noise), h−1 (flicker noise), and h−2  values are used to define the clock’s Allan variance and to model the clock error behaviour. The theoretical noise values of CSAC and TCXO clocks are obtained from In the frequency domain, the Allan variance, llators, ,19. The llators, .(2)σγ2 event generated by the GNSS receiver. The obtained steering values are time-filtered to avoid errors due to jitter noise. After the completion of the disciplining process the clock achieves its maximum stability. The accuracy of the final computed steering value depends on many factors such as aging, environment  and reference clock performance. For proper clock performance, the estimated steering value should be applied in every clock initialization. However, this value is not constant over time, and it must be periodically recomputed. The variability of the CSAC steering value is presented in the next section.τ = 3000 s. Other studies from the manufacturer specify that it is better to set τ = 5000 s [A critical step in the disciplining process is the selection of the data averaging time. A joint analysis of target clock error models and reference clock error models must be performed. This can be easily done by means of the Allan Variance charts: the optimal averaging time is that at which the noise of the reference clock and the noise of the target clock are the same. If the averaging time is lower than the intersection clock noise values, the algorithm will not reach the maximum stability due to the poor short-term stability of the reference oscillator. Otherwise, if the selected averaging time is higher than the intersected value, the algorithm will take more time to reach the stability. If it is wished to discipline a GNSS receiver, the data of = 5000 s . To obta−9) by the constant of light velocity [A brief review of the code-based position and clock correction estimation algorithm is presented in this section. One of the methods that GNSS receivers implement to estimate the position and clock correction value is through the pseudorange measurements, that is, the distance between the satellites and the receiver. In order to measure these pseudoranges the GNSS receiver computes the time that the signal takes to travel from the satellite to the receiver. As an initial approximation, if we do not consider the atmospheric (ionospheric and tropospheric) refractivity variations, it is possible to obtain the distance between the GNSS receiver and the satellite by using the speed of light constant. Finally, knowing the satellite positions, the receiver localization is obtained by means of triangulation. Since the clock receiver is not perfectly synchronized with the satellite’s clocks, the error in measuring travel times is directly translated into a systematic error in pseudoranges. This error can be up to 0.3 m for each pseudorange measurement, leading to a fully incorrect position estimation (few meters of error). The value of 0.3 m is obtained by the multiplication of the theoretical TCXO clock bias  are the unknown receiver position and the unknown receiver clock corrections (bias and drift). The drift is multiplied by a time increment (∆t) and c is the constant of light velocity. The receiver position is considered as a random walk process  and a drift process noise :−12 s, or equivalently below one millimetre. Thus, it can be assumed that the system is only able to determine a solution within specifications with three satellites. The following equations must be completed for each satellite and each available frequency:kP is the measured pseudorange, kX is the known satellite position, kK are the modelled or provided atmospheric and instrumental corrections, dt is the receiver clock correction, X are the unknown receiver position and c is the constant of light velocity. kv is the residual error.By using a stable oscillator, such as the CSAC (with a known clock model error), it is possible to estimate the position with only three satellites. This can be achieved for a period  by synchronizing the CSAC with the GNSS time. Due to the short-term stability performance, the CSAC can be considered as a reference clock value whose residual error is below 10−12 [In the new model, the receiver position is once again considered as a random walk process with a process noise , and only one with an atomic clock, were compared. Both receivers, when operating together, receive the same GNSS signal from a high-grade splitter . All of these elements can be easily identified in The configuration of the CSAC changes depending on the type of test to run. For example, in some scenarios the CSAC is evaluated after a disciplining  while in other scenarios, it is evaluated in a free running mode after setting up a steering value. More details on CSAC configuration commands can be found in ,16.In the same way, the Novatel GNSS receiver is configured to better adapt its behaviour to the type of test being performed. The main configuration options and log commands used are clock model data logging and external clock enabling/disabling.−10. Since our evaluation corroborates that the estimated steering value is strongly correlated with temperature , or interface board, introduce some delays that have to be taken into account. −8 m/s).The internal CSAC phase meter tool is used to measure cable delays. All cables used comply with the Conducfil RG-174/U 50 Ohm MIL C-17 standard. The manufacturer  specifieτ is the delay in the PCB line, τ0  is a generic delay for FR-4 grade microstrip lines [λ is the microstrip line length:An oscilloscope and a compensated probe are used to measure the delays in the PCB. ip lines  and λ isTo analyse the oscillator frequency response in relation to temperature, the first step is to discipline the CSAC. This is done using a GNSS receiver in a controlled temperature environment achieved by means of a climate chamber (CC). Several tests are required at different temperatures. The temperature ranges to consider are from 5 °C to 40 °C. The CSAC is set on disciplining mode (filter window = 5000 s) using the PPS signal from the GNSS  receiver set as an input; the monitored parameters are the steering and phase meter values.The output of this procedure is a series of temperature and steering related values within the tested range. With the data series, an equation is obtained to interpolate the values between each temperature step. This equation is used to calibrate the CSAC. The calibration consists of measuring the environmental temperature and setting up a CSAC steering adjustment value. Any change in temperature implies a change in the steering value applied to the CSAC. This is very important when working in dynamic environments, where the air/room temperature cannot be kept constant.This test intended to analyse the performance of the GNSS receivers when an outage occurs. Its purpose is to observe how the clock stability affects the receiver’s capability to re-track the satellites. To do this, the time elapsed between the moments when the signal is recovered and the receiver tracks the satellites again is measured. As in the previous tests, one of the GNSS receivers used its internal clock while the other one used the CSAC as an external clock see . DiffereA GNSS receiver using its internal TCXO;A GNSS receiver using an external CSAC, without temperature compensation; andA GNSS receiver using an external CSAC, with temperature compensation.Once the CSAC is modelled by temperature, three test scenarios are considered in order to evaluate the benefits on the positioning performance:For each of the scenarios the same conditions are used. The positioning solutions are cross-compared, evaluating the performance of the CSAC by applying the previously mentioned temperature calibration procedure. The lack of an independent reference position limited the evaluation of these results to their precision and not to their accuracy.Due to its high short-term stability, it is expected that the availability of the positioning solution will improve when a holdover happens. The drift of the CSAC clock with respect to the satellite clock must be some orders of magnitude lower than the drift of the TCXO stand-alone (without the GNSS corrections). Therefore, the ability of the GNSS receiver to more quickly recover the positioning solution must be easily noticeable when comparing it to a traditional GNSS receiver . The receiver manufacturer specified a Time to First Fix (TTF) for a hot start of 35 s and a signal reacquisition for L1 of 0.5 s .In terms of positioning accuracy, the vertical or height component (VDOP) should benefit the most from this CSAC augmentation configuration. This is because the vertical component has a strong correlation with the clock performance. No improvements are expected in planimetry. The use of atomic clocks as CSAC not only makes it possible to work with fewer observations (satellites) but also has an impact on the solution performance. With this equipment, the modelling of the clock parameter is simpler and more reliable, leading to a more accurate estimation. This improvement in the clock accuracy has an impact on the accuracy of the position unknowns. There are several studies ,5,12,13 i signal is mainly caused by the copper lines in the PCB, the PNP transistor and the AND logic gate placed between the SMA connector and the CSAC input pin  values of the system delay, which are shown in  pin see . In the Next, the obtained measurements were performed using an oscilloscope probe. A print screen of these measurements can be found in After evaluating the phase meter measurements of cable delays, an inconsistence between these measurements and the theoretical expected values was observed. All the measured values were significantly lower than expected (having a negative offset). We assume that this offset value is due to a time delay compensation stored in the CSAC internal memory set prior to shipment (from factory). Therefore, the measured values for cable delays shown in CC) and the temperature measured by the CSAC (TCSAC). It can be observed that there is a temperature bias of around 1.5 °C. This bias needs to be taken into account when assigning steering values related to environmental temperature.Before starting the calibration procedure, it is necessary to analyse the reliability of the temperature sensor of the CSAC. Initially, several tests at the same temperature are carried out inside the CC in order to observe the reliability of the steering values once the procedure converged. The computed values are plotted in Another effect observed from these tests, done with a time-lapse of three weeks, is that there is an aging drift in the data. This effect is evaluated more in detail in Once the determination of the steering values is performed, a set of acquisition campaigns was carried out at different temperatures. In the previous figure, the big changes in the measured steering parameter that are produced by a quick change in temperature (temperature steps) are easily observable.CSAC), expressed in degrees Celsius, by the CSAC.From that campaign, a second order equation relating steering values and temperature is derived (Equation (5)). The values shown in the equation were computed from tests similar to the one shown in It is worth mentioning that the initial steering values for the disciplining CSAC are very noisy because the algorithm has not reached the stable stage  is clearly observed. Henceforth, the last obtained values (03/06) were those used in the following tests.Several tests were performed to check the recovery time varying the duration of the signal outage. The results obtained in the 1-min test show that the use of the CSAC improves the recovery time. Please note that a case was found in which the TCXO behaved better than its nominal value. When increasing outages to 2 min b, it is The conclusions drawn from the tests above indicate that no improvements in the recovery time may be expected due to the use of the CSAC for signal outages shorter than 1 min. Beyond this time lapse, the CSAC clearly improves the time needed to re-track. Moreover, the time needed to recover the lock when using the CSAC is not affected by the duration of the outage; in contrast, it increases when using a TCXO. In all cases, the recovery time is below the TTF hot start manufacturer specifications .In This study presents a characterization of the CSAC, examining in detail the delays introduced by the interface (PCB) board for a better synchronization of CSAC and a GNSS receiver. The measured delay values are slightly different from the theoretical values but these minor differences could be due to the tolerances of the components used and some approximations of the values . It is also unknown whether the CSAC internally corrects the phase meter measurements, though the results seem to prove that it does. In any event, these results are considered consistent with the expectations.−12, see −9 s/month) in most of the cases, but not always (i.e., data series 18/03 and 08/04 in The temperature calibration process of the CSAC is proven as valid. The clock performance of the CSAC is greatly improved and the system is able to work in a dynamically changing environment, keeping the clock stability to its lowest possible value (10In the particular case of the holdover performance evaluation, everything worked as expected see . For shoIt was proved that the CSAC clock makes it possible to estimate position within specifications even when only three satellites are available. It has also been observed that the impact of reducing and simplifying the clock unknown has almost no impact in planimetry performance neither for static nor dynamic trajectories. However, the results demonstrate that having access to these precise clocks has a relevant impact on the performance of height estimations in both scenarios.Future research will focus on the study of the benefits of the use of a CSAC in jamming and spoofing scenarios. Moreover, the hot/warm/cold start behaviours in different scenarios can be more deeply evaluated.


Growth factors (GFs) are cytokines that regulate the neural development. Recent evidence indicates that alterations in the expression level of GFs during embryogenesis are linked to the pathophysiology and clinical manifestations of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). In this concise review, we summarize the current evidence that supports the role of brain-derived neurotrophic factor, insulin-like growth factor 2, hepatocyte growth factor (HGF), glial-derived neurotrophic factor, nerve growth factor, neurotrophins 3 and 4, and epidermal growth factor in the pathogenesis of ADHD and ASD. We also highlight the potential use of these GFs as clinical markers for diagnosis and prognosis of these neurodevelopmental disorders. During neural development, a myriad of biological events occurs simultaneously, i.e., neurogenesis, gliogenesis, cellular migration, cell differentiation, synapse formation, etc. These neurobiological processes are orchestrated by several growth factors (GFs) and help shape the postnatal brain . In the Neurodevelopmental disorders comprise a group of neurological conditions that are considered a public health problem with strong socioeconomic impact . These dSome of the most common neurodevelopment disorders are autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). These disorders generate a poor global performance throughout life. ADHD and ASD have a complex etiology and their pathophysiology remains unclear. ADHD and ASD are often comorbid disorders  that shaThe ADHD has the highest incidence rate among all neurodevelopmental disorders . ADHD isCatecholamine dysfunction is the main hypothesis to explain ADHD pathophysiology; specifically, the dysfunction in dopamine receptors D4, D5, and in dopamine transporter proteins , 41 in p2lox/2lox/93), characterized by low BDNF expression in the hippocampus, hypothalamus, and cortex, develop hyperactivity and aggression after stress , another animal model for ADHD, low expression level of BDNF mRNA and TrkB receptors were found in frontal cortex  mice (−/−) mice show a significant reduction in myelin proteolipid protein and myelin basic protein in the hippocampus and cortex, with a subsequent deficit in myelination (Patients with ADHD show ~5% reduction in brain volume  in severKO) mice . On the KO) mice . In thisKO) mice . Intereslination . Altogetlination . Methylplination , 52. A 6lination .Glial-derived neurotrophic factor (GDNF) is another GF-related to the pathophysiology of ADHD. GDNF is widely involved in the survival of serotonergic and dopaminergic neurons because it has neuroprotective effects against neuroinflammation and oxidative damage . UntreatVascular endothelial growth factor (VEGF) has an important role during brain development and repair . In stroInsulin-like growth factor 2 (IGF2) regulates normal development of cerebellum and hippocampus , 53, botAutism spectrum disorder is a neurodevelopmental disorder , 57 thatAcetylation is a common feature of the neurotrophic proteins encoded by at least 18 genes dysregulated in patients with ASD , 63. WhiThe brain volume is considered as clinical indicator of certain psychiatry disorder . In patiChildren with autism show low expression levels of Neurotrophin-4 (NTF4) in blood, which have been correlated to impairments in neuroplasticity . TGF-β1 Brain-derived neurotrophic factor serum levels are significantly increased in autism . High exvia MAPK, PKC, and Akt pathways in neural progenitor cells . EGF strongly promotes cell proliferation and differentiation or cells . Recentlor cells ]. Intereor cells . Similaror cells , who preor cells . Remarkaor cells . In addior cells . Elevateor cells . These aHepatocyte growth factor (HGF) is another molecule that has been involved in the development of ASD , 83. AltAttention-deficit/hyperactivity disorder and ASD are neurodevelopmental disorders with significant comorbidity. Increasing evidence indicates that they share some pathological features and some etiological factors. Alterations in the expression level of BDNF, GDNF, NGF, NTF3, NTF4, or EGF are common features between ADHD and ASD Figure . TherefoAG-C contributed in the conception idea for the article, in the manuscript writing, and in the table design. TC-O participated in the manuscript writing and in the table and the figure design. RG-C participated in the manuscript writing and in the table and figure design. OG-P contributed to the conception of the idea for the article and in the manuscript writing type.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Subduction zones facilitate chemical exchanges between Earth’s deep interior and volcanism that affects habitability of the surface environment. Lavas erupted at subduction zones are oxidized and release volatile species. These features may reflect a modification of the oxidation state of the sub-arc mantle by hydrous, oxidizing sulfate and/or carbonate-bearing fluids derived from subducting slabs. But the reason that the fluids are oxidizing has been unclear. Here we use theoretical chemical mass transfer calculations to predict the redox state of fluids generated during serpentinite dehydration. Specifically, the breakdown of antigorite to olivine, enstatite, and chlorite generates fluids with high oxygen fugacities, close to the hematite-magnetite buffer, that can contain significant amounts of sulfate. The migration of these fluids from the slab to the mantle wedge could therefore provide the oxidized source for the genesis of primary arc magmas that release gases to the atmosphere during volcanism. Our results also show that the evolution of oxygen fugacity in serpentinite during subduction is sensitive to the amount of sulfides and potentially metal alloys in bulk rock, possibly producing redox heterogeneities in subducting slabs. Although large variabilities of fO2 were shown to occur in subduction zones, especially in melange zones constituting the plate/mantle interface1, previous petrological and geochemical studies have shown that the redox state of the subducted mafic crust does not change during prograde metamorphism and that its redox budget remains relatively constant2. Therefore, other sources of fluids must be considered to explain the oxidized nature of arc magmas5.During subduction, the increase of pressure and temperature conditions in the subducting plate results in hydrous mineral breakdown and the release of volatile-rich fluids. The oxidized or reduced nature of the released fluids is controlled by mineral local equilibrium changes and can be monitored through the oxygen fugacity , volatiles and halogens enriched in arc magmas (e.g. 17). The dehydration of serpentinized mantle results in a net decrease in bulk rock volatile concentrations17 and Fe3+/∑e19. In addition, observations of hematite-magnetite assemblages in dehydrated serpentinites21 suggest a high fO2, from one to five log units above the Quartz-Fayalite-Magnetite (QFM) oxygen buffer, during antigorite breakdown in subduction zones which could be compatible with the release of oxidized S and C in slab-derived fluids. If correct, this model would have major implications for the cycling of volatiles between the Earth’s surface and interior, volcanic degassing , and the occurrence of metal sulfide ore deposits23. Although several studies have indicated some evidence of variations of fO2 in antigorite-bearing serpentinites that can be related to the extent of initial serpentinization25, there is at this time no consensus on the evolution of fO2 or the redox state of serpentinite-derived fluids during antigorite breakdown in subduction zones.Serpentinized mantle peridotites can constitute a major source of water at depth in subduction zones33. In the present study, we model the dehydration of antigorite-bearing serpentinite to investigate its potential to liberate highly oxidizing fluids in subduction zones. The model uses a conceptual scenario in which an initial fluid chemistry was set by reaction of water with an antigorite-bearing serpentinite at 630 °C before undergoing an increase of temperature to 660 °C at constant pressure. The initial model assemblage is composed of antigorite, olivine (XMg [Mg/(Fe + Mg)] = 0.885), clinochlore, magnetite, and tremolite in agreement with field observations from Padron-Navarta et al.34. This assemblage sets the initial fO2 which ranges from near QFM at 500 °C and 2.0 GPa to QFM + 4.2 at 650 °C and 2.0 GPa  model now enable the calculation of equilibrium constants involving minerals and aqueous ions, metal complexes, and organics to 6.0 GPa and 1,200 °CfO2, mineral assemblages, and fluid composition during antigorite breakdown at 2 GPa  in the rock  and corresponds to the disappearance of magnetite , Cl−(aq) and Si(OH)4(aq) and SiO(OH)3−(aq), with minor amounts of NaHCO3(aq), Al(OH)4−(aq), Ca(OH)+(aq), Mg(OH)+(aq), and FeCl2(aq). The presence of equilibrated hematite-magnetite assemblages in our models is compatible with recent observations in meta-peridotites from the Cerro Del Almirez massif21 or partly dehydrated serpentinites from Western Alps meta-ophiolites20. It therefore suggests that the dehydration of serpentinites in subduction zones can take place at high fO2, close to the hematite-magnetite buffer. At such P-T-fO2-pH conditions, volatile and redox-sensitive elements, such as sulfur or carbon, are expected to be mobilized under in their oxidized form (e.g. CO20aq) or SO42−(aq)) rather than reduced species (e.g. CH4(aq) or HS−(aq); Fig. Few variations in pH and the composition of the released fluids Fig.  are obsefO2 during prograde metamorphism is suggestive of oxidized fluids release during antigorite breakdown, previous studies have shown that the presence of Ni-Fe alloys and/or sulfides can buffer the fO2 down to four or five log units below the QFM buffer in serpentinites36. In addition, several studies have shown that sulfides can persist17 or even be formed25 during serpentinite devolatilization. In order to test the impact of sulfur-bearing phases during the progressive devolatilization of serpentinites in subduction zones, we ran a suite of models containing various amounts of pyrrhotite , which is commonly observed in abyssal and orogenic serpentinites17. The most pronounced difference between sulfide-free and sulfide-bearing models is the evolution of fO2 during the reaction progress , SO42−(aq), CaSO4 (aq), MgSO4 (aq)) are dominating the fluid composition relative to sulfide bearing species , the destruction of sulfide and then magnetite is accompanied by an increase of fO2 and the appearance of hematite , SO42−(aq), CaSO4 (aq) and MgSO4 (aq). For high sulfide concentrations (0.1 mole of pyrrhotite), aqueous sulphide species remain at significant concentrations in the fluid during the whole reaction progress and become more abundant than sulphate species above logξ of about −1.5 -Cl2 and/or Fe(II)-SOX20. In good agreement with these observations, thermodynamic calculations predict that during serpentinite dehydration, the magnetite modal amount significantly decreases  to sulfate is not considered in the DEW model and even though Fe(III)-complexes are included, they are completely unimportant at the relatively high temperatures and low chloride concentrations of the present study. In other words, with our present state of knowledge of aqueous Fe-complexes, there are none known that could contribute significantly to the transport of Fe(III). It should also be noted that chlorine concentrations in fluid inclusions hosted by metamorphic olivines range up to 2 wt% NaCl. Such chlorine concentrations could potentially lead to a higher mobility of Fe(II) in serpentinites-derived fluids15.Iron, carbon and sulfur are the main redox sensitive elements that can be transferred by fluids from the slab to the mantle wedge, having thus the potential to modify the redox state of the source region of arc magmas above subduction zonesses Fig.  while thses Fig.  and is d2,aq under the conditions we investigated in subduction zones. Sources of this C could be in sediments and ophicarbonates  reflecting a mobility of sulfur in serpentinite-derived fluids during subduction41. Indeed the presence of sulfur-bearing daughter phases precipitating after fluid entrapment in dehydrated serpentinite shows a significant mobility of sulfur in serpentinite derived fluids during subduction15. In agreement with these studies, sulfur-bearing models reveal the total destruction of sulfur-bearing phases during the first stages of serpentinite dehydration and the presence of sulfate in serpentinite-derived fluids. The ratio of total sulfate over total sulfur in serpentinite derived fluids increases with the fO2  can buffer the fO2 to relatively low values, until their eventual destruction during antigorite breakdown, while toward to the top of the slab and/or nearby slab-bending related fractures the ultramafic rocks will preferentially crystallize assemblages equilibrated at high fO2. As a consequence, the fO2 of the slab is likely to be heterogeneous, reflecting different pre-subduction mineralogy. However, in highly serpentinized peridotites, regardless of the considered models, sulfur seems to be highly mobile in fluids during antigorite breakdown , SO42−(aq), CaSO4 (aq), MgSO4 (aq)) always represent a significant proportion of the sulfur-bearing phases carried by the fluid. The migration of these fluids from the slab to the slab-mantle interface or mantle wedge can therefore enhance the oxidation of the mantle wedge Fe2+ to Fe3+ in response to the reduction of slab fluid SO42− to S2−. Such processes may provide an oxidized mantle source region for primary arc magmas. In this way, the origin of the oxidized signature carried by fluids from the slab may be an inevitable consequence of the breakdown of antigorite during subduction.The own Fig. . InteresSupplementary Figures


Early‐life institutional deprivation is associated with attention‐deficit/hyperactivity disorder (ADHD) later in childhood and adolescence. In this article, we examine, for the first time, the persistence of deprivation‐related ADHD into young adulthood in a sample of individuals adopted as young children by UK families after periods in extremely depriving Romanian orphanages.We estimated rates of ADHD at age 15 years and in young adulthood (ages 22–25 years) in individuals at low  and high deprivation‐related risk . Estimates were based on parent report using DSM‐5 childhood symptom and impairment criteria. At age 15, data were available for 108 LoDep and 86 HiDep cases, while in young adulthood, the numbers were 83 and 60, respectively. Data on education and employment status, IQ, co‐occurring symptoms of young adult disinhibited social engagement (DSE), autism spectrum disorder (ASD), cognitive impairment, conduct disorder (CD), callous‐unemotional (CU) traits, anxiety, depression and quality of life (QoL) were also collected.ADHD rates in the LoDep group were similar to the general population in adolescence (5.6%) and adulthood (3.8%). HiDep individuals were, respectively, nearly four (19%) and over seven (29.3%) times more likely to meet criteria, than LoDep. Nine ‘onset’ young adult cases emerged, but these had a prior childhood history of elevated ADHD behaviours at ages 6, 11 and 15 years. Young adult ADHD was equally common in males and females, was predominantly inattentive in presentation and co‐occurred with high levels of ASD, DSE and CU features. ADHD was associated with high unemployment and low educational attainment.We provide the first evidence of a strong persistence into adulthood of a distinctively complex and impairing deprivation‐related variant of ADHD. Our results confirm the powerful association of early experience with later development in a way that suggests a role for deep‐seated alterations to brain structure and function. Attention‐deficit/hyperactivity disorder (ADHD) characterised by developmentally inappropriate and impairing symptoms of inattention, impulsivity and hyperactivity is a childhood onset disorder with deleterious effects across the life span  study is especially compelling in this regard ?In this article, we provide the first evidence relating to the persistence of deprivation‐related ADHD into early adulthood using data from the recently completed ERA young adult follow‐up assessment carried out when the adoptees were aged 22–25 years. Our research questions were as follows:SD = .77) years and for the Romanian adoptees 23.6  years. A comparison of age 15 characteristics of those that dropped out in young adulthood and those that remained in the study provided no evidence of selective attrition. The proportion of HiDep and LoDep cases was similar at the two ages, and there was no difference between those remaining in the study at the young adult follow‐up and those dropping out in terms of sex of child, age, IQ, or the proportion of cases with deprivation‐related problems at age 15 years (data available from authors).One hundred and sixty‐five Romanian adoptees and 52 comparison UK adoptees with no history of deprivation, and their families, initially entered the study in the mid‐1990s. For the purposes of the current analysis, we split the sample into two groups  and, as far as possible, equivalent thresholds for symptom presence and impairment (i.e. DSM‐5 childhood criteria). Our primary analysis used a categorical DSM‐5 definition of ADHD, allowing us to anchor our observations against clinical norms. We supplemented this with group comparisons of counts of symptoms of inattention and hyperactivity/impulsivity.Data on ADHD were collected from parents as part of a modified Child and Adolescent Psychiatric Assessment (CAPA) interview  were assessed by the CBRS using standardised The Satisfaction with Life Scale . These were coded in a binary form .This was based on data on parents’ occupation at the age 15 follow‐up  = 0.27, p = .61] and early adulthood . There was also no difference in the ADHD rates for the Romanian adoptees experiencing 6–24 months and over 24 months of institutional deprivation . This pattern was replicated when continuous symptom counts rather than ADHD categories were used. The LoDep group contained a number of individuals (17 in adolescence and 11 in young adulthood) who were adopted straight from family homes. These individuals did not differ from the under 6‐month institutionalised group in terms of adolescent and young adult ADHD levels (ps > .31).Data on ADHD symptoms were available for 194 individuals in adolescence and 143 individuals in young adulthood. To check the validity of combining the UK and Romanian adoptees with less than 6‐month exposure to institutional deprivation, we compared ADHD rates in these two groups. Rates in both groups were similarly low in both adolescence . The 9‐ and 18‐item scales identified the same cases on 93.3% of occasions , for the predominantly inattentive presentation, and 93.8%  for any presentation.Figure F  = 30.32, p < .001, and F  = 21.05, p < .001, respectively. There was a slight increase in the number of both symptom types across the age transition. but the interaction between group and age did not reach significance, F  = .45, p = .51, and F  = 1.04, p = .31. Consistent with the preponderance of ADHD‐PI, inattention symptoms were approximately 50% more likely to be endorsed than hyperactivity/impulsivity symptoms in the HiDep group.Figure There were nine ‘adult onset’ and nine adolescent‐adult ‘persistent’ cases. Table T‐score estimates. The very high rates of unemployment  and low educational achievement (over 70%) in the ADHD+ group were significantly greater than in both other groups. Furthermore, QoL was lowest in the ADHD+ group.Table The form of ADHD observed in the current study in individuals exposed to severe deprivation in early childhood shares features with ADHD in typical clinical populations. It is also different in important ways. First, compared with ‘typical’ ADHD, it appears to be unusually persistent across the transition from adolescence to adulthood – a pattern previously seen in the ERA sample across childhood and early adolescence . A second possibility is that this form of ‘adult onset’, ADHD is a different sort of condition to the childhood variety occurring, rather, as a secondary feature of other co‐occurring conditions. This possibility has been raised in relation to adult onset cases of ADHD generally  for ADHD seem to operate, in general, to the detriment of boys, this suggests that girls are more vulnerable to the risks associated with deprivation, at least in terms of ADHD. However, it must be remembered that the mortality rates were relatively high in the Romanian institutions and there is a possibility that the most vulnerable males suffered a disproportionate level of mortality, with only the more resilient males surviving Kligman, .Second, while it is important to acknowledge that symptoms of hyperactivity and impulsivity were also elevated, there was a preponderance of the predominantly inattentive type following deprivation in the HiDep group. This may simply be a consequence of the high number of girls in the ERA ADHD population. However, there is evidence that executive functions are specifically compromised in institutionally deprived individuals – with deficits placing children specifically at risk for attentional rather than hyperactive and impulsive behaviours  being distinctive common associated features  and with reduced QoL. The clinical imperative is to ensure that early deprived individuals with ADHD get the specialist services they need and that these continue into adult life. In this regard, at around 40%, the lifetime rate of clinical engagement in the ERA sample was relatively high. More generally, the current findings highlight the importance of measuring early‐life exposures to adverse environments in children with ADHD during clinical assessments in order to properly address the especially persistent and complex nature of the problems such individuals present.The current study had significant strengths including its prospective nature and the stratification of deprivation‐related risk to increase statistical power. There were also a number of limitations that need to be considered when interpreting its findings. One related to the way that ADHD symptoms were assessed. First, different approaches were used in adolescence and young adulthood to collect ADHD information – parental interview in adolescence and questionnaire in young adulthood. Second, information on only nine ADHD items was collected during the adolescent interview. We addressed these constraints by using a categorical approach to measuring ADHD – to reduce the impact of the different scaling properties of the two instruments on scores; by restricting the main young adult analyses to the same nine symptoms assessed in adolescence and adjusting the diagnostic thresholds accordingly; and by employing the same DSM childhood criteria at both ages (i.e. not employing the new DSM‐5 adult criteria). This approach led to plausible estimates of ADHD rates in the LoDep group. While we were initially concerned that use of questionnaires in the young adult sample would inflate rates, in fact the rates in the LoDep group were lower in the young adult assessment than in the adolescent assessment. Crucially, when rates of young adult ADHD were based on the full 18 items, they were very similar to those derived using the nine‐item scale. The level of agreement between the two versions was also high.A second limitation concerned the level of attrition at the young adult assessment, which was much higher than the very low rates previously seen in the study. This, although not surprising given the age range of the young adults, limited the statistical power of the analysis, especially in the comparison of ADHD and non‐ADHD subgroups. Crucially, however, there was no evidence that attrition was selective, with those retained to young adulthood and those lost to the study after the age 15 follow‐up differing little on key measures. In addition, all the analyses reported in this article were conducted again only for those individuals with data at both ages and the effects did not change. A third limitation relates to the limited number of young adult measures available for analysis of co‐occurring difficulties. Unfortunately, measures of personality disorders and substance abuse were not available for analysis at the time of writing this article. A final limitation was that reports of impairments used to identify ADHD cases could not be tied specifically to ADHD symptoms and could have been a product of co‐occurring problems.In summary, this study provides the first evidence of a strongly persistent and distinctively complex and impairing institutional deprivation‐related variant of adult ADHD. This highlights the powerful impact of early experience on later development in a way that potentially implicates deep‐seated neurobiological alterations. Clinical services need to be especially mindful of the need to ensure an effective transition from adolescent to young adult services in ADHD individuals exposed to early adversity.Early severe institutional deprivation is associated with adverse long‐term outcomes in a substantial minority of cases.In the English and Romanian Adoptees study, ADHD− is a characteristic feature of a pattern of deprivation‐related childhood and adolescent problems also including quasi‐autism, disinhibited social engagement, and cognitive impairment.This study provides the first evidence of a persistent variant of adult ADHD found in individuals exposed to severe institutional deprivation early in childhood.Deprivation‐related adult ADHD was distinctive in terms of frequency of the inattentive presentation, high proportion of females and co‐occurrence with disinhibited social engagement, ASD symptoms and CU traits.The strong persistence and complex nature of ADHD in adults exposed to severe early deprivation highlights the need to optimise continuity and cooperation between child and adult clinical services.


Low birthweight (LBW) is a major predictor of early neonatal mortality which disproportionately affects low-income countries. WHO recommends regional definitions for LBW to prevent misclassifications and ensure appropriate care of babies with LBW. We conducted this study to define a clinical cut-off for LBW, and to determine the predictors and adverse foetal outcomes of LBW babies in a rural sub-division in Cameroon.We conducted a retrospective register analysis of 1787 singleton deliveries in two health facilities in the Northwest Region of Cameroon. Records with no birthweight or birthweight less than 1000 g, babies born before arrival, multiple deliveries and deliveries before 28 weeks gestation were excluded from this study. The 10th percentile of birthweights was computed to obtain a statistical cut-off value for the LBW. To assess the clinical significance of the newly defined cut-off value, we compared the prevalence of adverse foetal outcomes between LBW (birthweight <10th percentile) and heavier babies (birthweight ≥10th percentile) in our study population.p = 0.001). LBW babies were more likely to be stillborn  or asphyxiated at the 5th minute , compared with heavier babies. Also, 6.1% of babies who had a birthweight between 2500 and 2700 g were more likely to be stillborn compared to heavier babies.The 10th percentile of the birthweights was 2700 g. Preterm delivery was the lone predictor of LBW (aOR = 2.0, 95% CI = 1.3–3.1; This study suggests that the clinical cut-off for LBW in this rural community is 2700 g; with 6.1% of babies born with LBW probably receiving inadequate care as the traditional cut-off value of 2500 g proposed by WHO is still used to define LBW in our setting. Further studies are necessary to define a national cut-off value for harmonisation of LBW definitions in the country to prevent misclassifications and ensure appropriate neonatal care. The World Health Organisation (WHO) defines low birthweight (LBW) as the weight of a neonate below 2500 g at birth, often corresponding to the 10th percentile for its gestational age , 4. GlobThe study methodology has been described in a previous study . BrieflyAll delivery records during the study period were reviewed. Eligible for inclusion were all singleton hospital deliveries. We excluded records with no birthweight or birthweight less than 1000 g, babies born before arrival, multiple deliveries and deliveries before 28 weeks gestation. Out of the 2343 delivery records reviewed, 1787 were retained, giving a response rate of 76.4%.We collected data on sociodemographic and clinical characteristics of all included mother-neonate pairs which included: age, marital status, gravidity, parity, gestational age, human immunodeficiency virus (HIV) serologic status and gender of the neonate. Foetal outcome parameters such as: birthweight, fifth minute Apgar score, and stillbirth were also collected. Variables were categorised as shown in Table p-values < 0.25. Two sided p-values less than 0.05 were considered statistically significant.Data were entered and analysed using the Statistical Package for Social Sciences (SPSS) version 20.0. Categorical variables are presented as frequencies, proportions and percentages, while continuous variables are presented as means (Standard Deviation) and median (Inter-Quartile Range), where appropriate. The 10th percentile of the birthweights was computed to obtain the cut-off for LBW in our study population. The kappa Cohen coefficient was used to evaluate levels of agreement between the newly defined cut-off, the traditional cut-off value and the local cut-off proposed by Njim and colleagues . To asseEthical approval for the conduct of this study was granted by the Regional delegation of public Health of the Northwest Region of Cameroon and by the directorate of both partaking hospitals.p = 0.001; Table p < 0.001) or suffer from birth asphyxia at the fifth minute of life , Table p = 0.006; Table Overall, 1787 records were eligible for this study. Maternal ages ranged from 14 to 49 years, with a mean age of 26 ± 6.5 years. Over three quarters of women in our study were married by the time of delivery. Also, one quarter of the women were delivering for their first time. There was an equal number of male as female neonates  entered into the delivery registers might not be accurate as it is subject to recall bias. The length of the gestation is also crucial in predicting neonatal morbidity and mortality , and simBeing a retrospective study, we had no influence on the quality of data entered into the delivery registers. The risk of other neonatal complications like neonatal infection, admission to the neonatal unit, and hypoglycaemia, for example, could not be evaluated due to unavailability of relevant data. In addition, predictors of LBW such as use of recreational drugs, smoking and alcohol consumption during pregnancy could not be assessed due to lack of data collected on these variables in our delivery registers. This study was not designed to identify constitutional causes of LBW (genetic predisposition), highlighting the need for further research in this domain. However, with the large sample size (1787 newborns) and a robust statistical analysis controlling potential confounders, we ruled out several potential biases in the results obtained.We have demonstrated that the clinical cut-off for LBW in this rural community is 2700 g, with preterm delivery being the sole determinant of LBW. LBW babies were more likely to be stillborn or asphyxiated at the fifth minute of life. A significant proportion of these babies may be receiving inadequate neonatal care as the traditional cut-off of 2500 g proposed by the WHO is still used to define LBW in this rural area. However, more data is needed through a prospective study design with larger sample size to define a cut-off value for LBW over the national territory; as this will guide the implementation of effective preventive strategies to curb the morbidity and mortality associated with LBW in Cameroon. While pursuing the validation of a cut-off value for LBW on a larger scale in Cameroon, it is prudent to adopt our current cut-off value for LBW in this rural community.