Euclidean matchings and minimality of hyperplane arrangements

We construct a new class of maximal acyclic matchings on the Salvetti complex of a locally finite hyperplane arrangement. Using discrete Morse theory, we then obtain an explicit proof of the minimality of the complement. Our construction provides interesting insights also in the well-studied case of finite arrangements, and gives a nice geometric description of the Betti numbers of the complement. In particular, we solve a conjecture of Drton and Klivans on the characteristic polynomial of finite reflection arrangements. The minimal complex is compatible with restrictions, and this allows us to prove the isomorphism of Brieskorn’s Lemma by a simple bijection of the critical cells. Finally, in the case of line arrangements, we describe the algebraic Morse complex which computes the homology with coefficients in an abelian local system

The essence of psychologic and pedagogical diagnostics

Уточняется понятие «психолого-педагогическая диагностика», рассматриваются функции, принципы, этапы психолого-педагогической диагностикиIn the article the idea of «psychologic and pedagogical diagnostics» is precised, also there are facilities, values, and phases of psychologic and pedagogical diagnostic

Primary Human Natural Killer Cells Retain Proinflammatory IgG1 at the Cell Surface and Express CD16a Glycoforms with Donor-dependent Variability

Post-translational modification confers diverse functional properties to immune system proteins. The composition of serum proteins such as immunoglobulin G (IgG) strongly associates with disease including forms lacking a fucose modification of the crystallizable fragment (Fc) asparagine(N)-linked glycan that show increased effector function, however, virtually nothing is known about the composition of cell surface receptors or their bound ligands in situ due to low abundance in the circulating blood. We isolated primary NK cells from apheresis filters following plasma or platelet donation to characterize the compositional variability of Fc g receptor IIIa / CD16a and its bound ligand, IgG1. CD16a N162-glycans showed the largest differences between donors; one donor displayed only oligomannose-type N-glycans at N162 that correlate with high affinity IgG1 Fc binding while the other donors displayed a high degree of compositional variability at this site. Hybrid-type N-glycans with intermediate processing dominated at N45 and highly modified, complex-type N-glycans decorated N38 and N74 from all donors. Analysis of the IgG1 ligand bound to NK cell CD16a revealed a sharp decrease in antibody fucosylation (43.2 ±11.0%) versus serum from the same donors (89.7 ±3.9%). Thus, NK cells express CD16a with unique modification patterns and preferentially bind IgG1 without the Fc fucose modification at the cell surface

Does dietary calcium interact with dietary fiber against colorectal cancer? : a case-control study in Central Europe

BACKGROUND: An unfavorable trend of increasing rates of colorectal cancer has been observed across modern societies. In general, dietary factors are understood to be responsible for up to 70% of the disease’s incidence, though there are still many inconsistencies regarding the impact of specific dietary items. Among the dietary minerals, calcium intake may play a crucial role in the prevention. The purpose of this study was to assess the effect of intake of higher levels of dietary calcium on the risk of developing of colorectal cancer, and to evaluate dose dependent effect and to investigate possible effect modification. METHODS: A hospital based case–control study of 1556 patients (703 histologically confirmed colon and rectal incident cases and 853 hospital-based controls) was performed between 2000–2012 in Krakow, Poland. The 148-item semi-quantitative Food Frequency Questionnaire to assess dietary habits and level of nutrients intake was used. Data regarding possible covariates was also collected. RESULTS: After adjustment for age, gender, education, consumption of fruits, raw and cooked vegetables, fish, and alcohol, as well as for intake of fiber, vitamin C, dietary iron, lifetime recreational physical activity, BMI, smoking status, and taking mineral supplements, an increase in the consumption of calcium was associated with the decrease of colon cancer risk (OR = 0.93, 95% CI: 0.89-0.98 for every 100 mg Ca/day increase). Subjects consumed >1000 mg/day showed 46% decrease of colon cancer risk (OR = 0.54, 95% CI: 0.35-0.83). The effect of dietary calcium was modified by dietary fiber (p for interaction =0.015). Finally, consistent decrease of colon cancer risk was observed across increasing levels of dietary calcium and fiber intake. These relationships were not proved for rectal cancer. CONCLUSIONS: The study confirmed the effect of high doses of dietary calcium against the risk of colon cancer development. This relationship was observed across different levels of dietary fiber, and the beneficial effect of dietary calcium depended on the level of dietary fiber suggesting modification effect of calcium and fiber. Further efforts are needed to confirm this association, and also across higher levels of dietary fiber intake

Novel Platforms for the Development of a Universal influenza vaccine

Despite advancements in immunotherapeutic approaches, influenza continues to cause severe illness, particularly among immunocompromised individuals, young children, and elderly adults. Vaccination is the most effective way to reduce rates of morbidity and mortality caused by influenza viruses. Frequent genetic shift and drift among influenzavirus strains with the resultant disparity between circulating and vaccine virus strains limits the effectiveness of the available conventional influenza vaccines. One approach to overcome this limitation is to develop a universal influenza vaccine that could provide protection against all subtypes of influenza viruses. Moreover, the development of a novel or improved universal influenza vaccines may be greatly facilitated by new technologies including virus-like particles, T-cell-inducing peptides and recombinant proteins, synthetic viruses, broadly neutralizing antibodies, and nucleic acid-based vaccines. This review discusses recent scientific advances in the development of next-generation universal influenza vaccines.Funding Agencies|GlaxoSmithKline Biologicals SA; Marie-Curie IEF grant SAMUFLU FP7-PEOPLE-IEF [626283]; Marie-Curie ITN grant HOMIN FP7-PEOPLE-ITN [626283]</p

IgG and Fcγ Receptors in Intestinal Immunity and Inflammation.

Fcγ receptors (FcγR) are cell surface glycoproteins that mediate cellular effector functions of immunoglobulin G (IgG) antibodies. Genetic variation in FcγR genes can influence susceptibility to a variety of antibody-mediated autoimmune and inflammatory disorders, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). More recently, however, genetic studies have implicated altered FcγR signaling in the pathogenesis of inflammatory bowel disease (IBD), a condition classically associated with dysregulated innate and T cell immunity. Specifically, a variant of the activating receptor, FcγRIIA, with low affinity for IgG, confers protection against the development of ulcerative colitis, a subset of IBD, leading to a re-evaluation of the role of IgG and FcγRs in gastrointestinal tract immunity, an organ system traditionally associated with IgA. In this review, we summarize our current understanding of IgG and FcγR function at this unique host-environment interface, from the pathogenesis of colitis and defense against enteropathogens, its contribution to maternal-fetal cross-talk and susceptibility to cancer. Finally, we discuss the therapeutic implications of this information, both in terms of how FcγR signaling pathways may be targeted for the treatment of IBD and how FcγR engagement may influence the efficacy of therapeutic monoclonal antibodies in IBD

Hyperplane Arrangment and Discrete Morse Theory

The aim of this thesis is to study the complement of a hyperplane arrangement using the techniques of Discrete Morse theory. A hyperplane arrangement is simply a set A={H_1,H_2,...} of hyperplanes in a vector space. This object has been widely studied especially to find correlations between its topological properties and the combinatorics of the intersections of the hyperplanes. One of the most studied topological objects is the complement, i.e. the vector space minus the hyperplanes and its homology and homotopy groups. One of the question that we are going to answer is if this complement is a minimal space, meaning that it is homotopy equivalent to a CW-complex with as many i-cells as the i-th Betti number. We will see that the answer is positive in various settings. Having a minimal complex, if it is given explicitly, can also help in studying various properties of the complement, we will focus in particular on abelian local homology. Local homology is an important tool for the study of hyperplane arrangements because it gives us informations on a special fibration on the complement, called Milnor fibration as well as informations about the characteristic varieties. Even if there is plenty of research on the subject there is still a lot unknown about local homology even for the most famous arrangements, like the Braid ones. In the first chapter we talk about Discrete Morse theory, first introduced by Forman. The aim is to reduce a CW-complex or in general various type of topological and combinatorial object to smaller ones, called Morse complex with a series of elementary collapsments such that the properties of the complex are still the same. We will study explore the correlation of this theory with shellability and focus on different aspect, all of which will became useful in the following chapters. In the second chapter, we first give a brief introduction to the theory of hyperplane arrangement, presenting some of the most important known results, concerning in particular their combinatorial properties and homology groups. In the special case of complexified real arrangement we introduce the Salvetti complex, a $CW-$complex homotopy equivalent to the complementary of the arrangement. We then review three different articles that with similar techniques have reduced this complex to a minimal one (with as many cells as the Betti numbers). The following chapter introduce the concept of local homology and its correlations with Discrete Morse theory, in particular how we could compute the local homology of the Morse complex. We focus then our attention to a special kind of hyperplane arrangement, called the Braid arrangement and we explicitly write a program in Sage to compute the boundary in local homology. In the last chapter we try to give our small contribute to the subject. It is a joint work with Giovanni Paolini in which in a similar way to what has been done by Delucchi in the case of oriented matroids, we reduce the Salvetti complex in the case of affine, locally finite hyperplane arrangment to a minimal Morse complex giving a special characterization to the critical cells

Ancestry and chance shape the selection, specialization and speciation of «Chlamydomonas reinhardtii» in a long-term evolution experiment

This thesis explores how populations evolve and adapt to large-scale environmental shifts over thousands of generations. Populations of Chlamydomonas reinhardtii of independent ancestry were exposed to novel environments that provided ecological and reproductive challenges for these unicellular autotrophs. Reciprocal transplant experiments were used intermittently throughout 19 years (roughly 7000 generations) of selection, to investigate the progression of evolutionary adaptation, specialization, and radiation. Chapter 1 compares the growth of C. reinhardtii strains selected in a heterotrophic environment with the ancestral autotrophically propagated population. Multiple replicates were set up in order to observe the interactions between selection, chance and ancestry and how they influence the repeatability of evolution. Traits under direct selection, namely heterotrophic growth capacity, are heavily influenced by selection environment and demonstrate large-scale allele frequency shifts occurring in independent replicates. Ancestry and chance, on the other hand, play a supporting role in terms of population dynamics. Traits under indirect selection, such as autotrophic and mixotrophic proficiency, ancestry greatly influences the evolutionary outcome and the likelihood of observing extreme phenotypes non-viable in the ancestral environment. This experiment shows that not only have the ecological niches of the replicate samples shifted in response to direct selection, but are also directed by historical contingencies within the populations.Chapter 2 further explores the concept of diversification and how prolonged selection can lead to specialization that can ecologically and reproductively isolate a formerly homogeneous population. The same founding populations of Chlamydomonas reinhardtii from the previous section were grown in opposing environments: liquid (ZIF populations) and solid (MOP populations) media, which provide vegetative and reproductive growth challenges. A classic reciprocal transplant experiment was conducted on the replicate populations of differing ancestry, where fitness and reproductive vitality was approximated through counting the number of zygotes arising from crosses between and within populations in both environments. Consistently higher vegetative growth and unique morphological adaptations were observed[iv]when populations were surveyed in their native environment. Offspring number is significantly higher when mating occurs within a single population in their preferred environment, while crosses between MOP and ZIF populations produce intermediate zygote numbers. The environment in which the cross occurs directly influences the number of viable zygotes resulting from the mating, especially when inoculated in solid media. These environmental barriers to gene flow coupled with significant ecological divergence among MOP and ZIF populations exacerbates this reduction in gene flow and reinforces selective mating upon secondary contact.Cette thèse examine comment les populations évoluent et s'adaptent aux changements environnementaux à long terme. Des populations de Chlamydomonas reinhardtii d'ascendance indépendante ont été exposées à de nouveaux environnements qui ont fourni des défis écologiques et reproductifs pour ces autotrophes unicellulaires. Les expériences de transplantation réciproque ont été utilisées de façon intermittente au cours des 19 années (7000 générations) de sélection, afin d'étudier la progression de l'adaptation évolutive, la spécialisation et la radiation adaptative. Le premier chapitre compare la croissance de C. reinhardtii sélectionnées dans un environnement hétérotrophe avec la population ancestrale propagée autotrophiquement. De multiples répétitions ont été mises en place afin d'observer les interactions entre sélection, hasard et ascendance ainsi que sur la manière dont ils influencent la répétabilité de l'évolution. Les traits sous sélection directe, à savoir la capacité de croissance hétérotrophe, sont fortement influencés par l'environnement de sélection et démontrent des changements de fréquence allélique à grande échelle se produisant dans des échantillons indépendants. L'ascendance et le hasard, cependant, jouent un rôle de soutien. En revanche, dans les cas de traits sous sélection indirecte, tels que la compétence autotrophique et mixotrophique, le résultat évolutif est grandement influencé par l'ascendance et la probabilité d'observer de nouveaux phénotypes augmente. Cette expérience montre que non seulement les niches écologiques durant l'expérience sont déplacées en réponse à la sélection directe, mais sont également dirigées par des contingences historiques au sein des populations.Le chapitre deux examine comment la diversification écologique et la façon dont la sélection prolongée peut mener à une spécialisation pouvant isoler sur le plan écologique et reproductif, une population autrefois homogène. L'expérience consiste en trois populations homogènes fondatrices de Chlamydomonas reinhardtii qui ont été cultivées dans les conditions liquides (populations ZIF) ou solides (populations MOP), qui fournissent des problèmes en termes de croissance végétative et reproductive. Une expérience de transplantation réciproque classique a été menée où l'aptitude et la vitalité reproductive ont été estimées en comptant le[vi]nombre de zygotes présents après des croisements entre et au sein des populations dans les deux environnements. Une croissance végétative constamment plus élevée et des adaptations morphologiques uniques ont été observées lorsque les populations ont été examinées dans leur environnement naturel. Le nombre de descendants est significativement plus élevé lorsque l'accouplement se produit entre les populations dans leur environnement de prédilection, tandis que les croisements des populations MOP et ZIF produisent des nombres de zygotes intermédiaires. L'environnement influence directement le nombre de zygotes viables résultant de l'accouplement, en particulier lorsqu'il est inoculé dans des milieux solides où la reproduction sexuelle est difficile. Ces obstacles environnementaux à l'écoulement des gènes couplés à une divergence écologique significative parmi les populations MOP et ZIF aggravent l'isolement reproductif et renforcent l'accouplement sélectif au contact secondaire