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Questions and conjectures about the modular representation theory of the general linear group GLn(F2) and the Poincar\'e series of unstable modules
This note is devoted to some questions about the representation theory over
the finite field of the general linear groups
and Poincar\'e series of unstable modules. The first draft
was describing two conjectures. They were presented during talks made at VIASM
in summer 2013. Since then one conjecture has been disproved, the other one has
been proved. These results naturally lead to new questions which are going to
be discussed. In winter 2013, Nguyen Dang Ho Hai proved the second conjecture,
he disproved the first one in spring 2014. Up to now, the proof of the second
one depends on a major topological result: the Segal conjecture. This
discussion could be extended to an odd prime, but we will not do it here, just
a small number of remarks will be made
Cell Sorting in Pillar Arrays based on Electrokinetics and Morphology
Deterministic Lateral Displacement (DLD) is a method capable of sorting cells based on size where mechanicalinteractions between a sufficiently large particle and obstacles in a microfludic pillar array force the particle tofollow a different trajectory than their smaller counterparts, resulting in continuous lateral separation. To extendthe capability of DLD, electrical interaction between particles and pillars can be employed to complement themechanical interaction, making electrical/dielectric properties additional parameters for sorting. Another idea isto exploit the morphologies of cells and as a concequence, their dynamical properties, to sort them in DLD. Thedevelopment of DLD cell sorting methods based on those two ideas has brought forth five papers appended to thisthesis: paper I, III, and V (combination of electrokinetics and DLD), and paper II and IV (exploiting morphologyin sorting by DLD).In the first topic, differences in electric properties or dielectric properties of particles and cells are employed toextend the capability of DLD. In Paper I, an AC electric field was applied across DLD devices having insulatingpillars to sort similar-sized polystyrene particles having different surface charge, viable from non-viable yeast cells,and viable from non-viable E. coli bacteria. In Paper III, the same method was utilised on open channel DLDdevices, showing unaltered effectiveness but offering the ability to flexibly change the distance between the electrodes.Also in the topic of combining electrokinetics and DLD, Paper V introduced a new type of DLD devicewhere the electrodes were defined locally on every pillar, making it easier to generate a high electric field strength.Besides electrical properties, morphology is another useful accompaniment to DLD. In Paper II, pathogenicStreptococcus pneumoniae bacteria were fractionated in DLD devices according to the difference in their morphology,viz. their chain length. It was also demonstrated, in paper IV, that an AC field can be used to rotatenon-spherical red blood cells and in turn, change their trajectory in a DLD device. This implies an opportunity tosort red blood cells from cells having different morphology, either spherical cells or parasites like trypanosomes
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Epidemiology of Streptococcus suis infection in Viet Nam
Human Streptococcus suis infection is an emerging zoonotic disease in Southeast Asian countries. It can seriously threaten human heath causing both outbreaks with high morbidity and mortality and endemic disease. It can also have a major negative impact on the economically important pig industry across the region. The aims of this thesis were to understand the epidemiology of human S. suis infection in Viet Nam, focusing on the incidence rate, seasonality and risk factors for infection with S. suis.
I conducted a prospective surveillance of central nervous system (CNS) infections in twelve provinces of Viet Nam including the Central, the Highlands and the south of the country. I was able to demonstrate that S. suis was an endemic disease across southern Viet Nam, and responsible for 49% of adult purulent bacterial meningitis. The incidence rate was 0.57 per 100,000 adult person-years (95% CI, 0.47-0.70) and infection had a case fatality rate of 8%. S. suis meningitis tended to predominantly occur in the hottest months of the year in central Viet Nam, but this
seasonal pattern was not documented in the south of the country.
A case control study demonstrated that occupational exposure to pigs or pork was a significant risk factor for S. suis infection. I was also able to identify novel and important risk factors for S. suis disease among the Vietnamese population. Eating fresh blood and undercooked pig products (OR1 = 2.22; 95%CI = [1.15-4.28] and OR2 = 4.44; 95%CI = [2.15-9.15]) and exposures of people with skin injuries to pigs or pork (OR = 7.48; 95% CI = [1.97-28.44] and OR2 = 15.96; 95%CI = [2.97-85.72]), were significant risk factors. These risk factors can be addressed in health education programs targeted at individuals and communities at risk, focusing on skin protection for those in direct contact with pigs or pork and avoiding eating fresh blood and undercooked pig products. In addition, we were unable to detect S. suis serotype 2 DNA from the throat and rectal swab samples of 1523 healthy persons and non-S. suis infected patients, including those with exposure to pigs and pork meat. Hence I was not able to demonstrate human carriage of S. suis serotype 2 in the Vietnamese population
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