The trick in building a vented box is to get the right size enclosure and the right size vent. You can't be too far off on either of these factors or your speaker's performance will suffer. In particular, using a too-small box or a too-high vent tuning frequency can eliminate bass instead of increasing it.
1 Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. 2  Symptoms include severe joint and muscle pain, swollen lymph nodes, headache, fever, exhaustion, and rash. 3  The presence of fever, rash, and headache (the dengue triad) is characteristic of dengue fever.
Severe dengue initially presents with the common symptoms of dengue fever such as fever, intense headache, aches and pains, loss of appetite, nausea, vomiting, skin rashes and leukopenia (reduction in white blood cells). A positive tourniquet test is also a sign of dengue fever.evere dengue may also occur when a person who has developed immunity to one strain of the virus becomes infected with another strain. There are four different strains of the dengue virus â DEN 1, 2, 3, 4. In 2013, in Singapore, over 50 per cent of dengue fever cases were due to the DEN-1 virus strain.