RURAL CREDIT RATIONING AND NATIONAL DEVELOPMENT BANKS IN DEVELOPING COUNTRIES

A common problem in agricultural credit markets in developing countries is the coexistence of a competitive market equilibrium interest rate and credit rationing. The literature typically explains the existence of credit rationing in competitive credit markets using adverse selection and moral hazard. Unfortunately these analyses are not consistent with the empirical reality that developing countries deal with in terms of subsidized credit, especially in the agricultural sector. This paper presents an alternative explanation for credit rationing in the agricultural sector in developing countries based on the fact that the requested loans are usually for small amounts, with many farmers making applications. As a result, the costs of operation increase with the number of loans given, so that inefficiencies in credit allocation occur when national development banks are present. It is shown that credit rationing can be reduced if shutting-down the national development bank is a feasible policy. Two other cases show that a national development bank is welfare-improving if an incentive compatible contract is used.Financial Economics,

Probabilistic models of individual and collective animal behavior

Recent developments in automated tracking allow uninterrupted, high-resolution recording of animal trajectories, sometimes coupled with the identification of stereotyped changes of body pose or other behaviors of interest. Analysis and interpretation of such data represents a challenge: the timing of animal behaviors may be stochastic and modulated by kinematic variables, by the interaction with the environment or with the conspecifics within the animal group, and dependent on internal cognitive or behavioral state of the individual. Existing models for collective motion typically fail to incorporate the discrete, stochastic, and internal-state-dependent aspects of behavior, while models focusing on individual animal behavior typically ignore the spatial aspects of the problem. Here we propose a probabilistic modeling framework to address this gap. Each animal can switch stochastically between different behavioral states, with each state resulting in a possibly different law of motion through space. Switching rates for behavioral transitions can depend in a very general way, which we seek to identify from data, on the effects of the environment as well as the interaction between the animals. We represent the switching dynamics as a Generalized Linear Model and show that: (i) forward simulation of multiple interacting animals is possible using a variant of the Gillespie's Stochastic Simulation Algorithm; (ii) formulated properly, the maximum likelihood inference of switching rate functions is tractably solvable by gradient descent; (iii) model selection can be used to identify factors that modulate behavioral state switching and to appropriately adjust model complexity to data. To illustrate our framework, we apply it to two synthetic models of animal motion and to real zebrafish tracking data.Comment: 26 pages, 11 figure

Rapes seldom reported

Statistics from the Rape Crisis Center in Bangor suggest that for every rape reported at UMO each year, 10 others have probably occurred, said UMO\u27s assistant director of police services William Prosser. The Rape Crisis Center bases unreported rape figures on calls [it] gets for assistance compared to the number of police reports generated due to rape, Prosser said

A generalization of Gabriel's Galois covering functors and derived equivalences

Let $G$ be a group acting on a category $\mathcal{C}$. We give a definition for a functor $F\colon \mathcal{C} \to \mathcal{C}'$ to be a $G$-covering and three constructions of the orbit category $\mathcal{C}/G$, which generalizes the notion of a Galois covering of locally finite-dimensional categories with group $G$ whose action on $\mathcal{C}$ is free and locally bonded defined by Gabriel. Here $\mathcal{C}/G$ is defined for any category $\mathcal{C}$ and we do not require that the action of $G$ is free or locally bounded. We show that a $G$-covering is a universal "$G$-invariant" functor and is essentially given by the canonical functor $\mathcal{C} \to \mathcal{C}/G$. By using this we improve a covering technique for derived equivalence. Also we prove theorems describing the relationships between smash product construction and the orbit category construction by Cibils and Marcos (2006) without the assumption that the $G$-action is free. The orbit category construction by a cyclic group generated by an auto-equivalence modulo natural isomorphisms (e.g., the construction of cluster categories) is justified by a notion of the "colimit orbit category". In addition, we give a presentation of the orbit category of a category with a monoid action by a quiver with relations, which enables us to calculate many examples.Comment: Title changed. Definitions of $\mathrm{Mod}^G\mathcal{C}$ and $\mathrm{Mod}_G\mathcal{B}$ in section 6 were corrected. Proof of Theorem 8.1 is slightly changed to make it more readable. Other minor change

Global Dimension of Polynomial Rings in Partially Commuting Variables

For any free partially commutative monoid $M(E,I)$, we compute the global dimension of the category of $M(E,I)$-objects in an Abelian category with exact coproducts. As a corollary, we generalize Hilbert's Syzygy Theorem to polynomial rings in partially commuting variables.Comment: 11 pages, 2 figure

Contribution du régulon sigma B à la pathogenèse de variants de STAPHYLOCOCCUS AUREUS formant de petites colonies lors d'infections pulmonaires chroniques chez les patients atteints de fibrose kystique

Bien que la fibrose kystique soit fondamentalement causée par une défectuosité génétique, les infections microbiennes sont la plus grande cause de mortalité des gens qui en sont atteints. La bactérie Staphylococcus aureus est un des pathogènes les plus communs associés à cette maladie et est la cause d'infections persistantes et difficiles à traiter. Des souches variantes de S. aureus formant de petites colonies (les s[barbelow]mall-c[barbelow]olony v[barbelow]ariants ou SCVs) sont fréquemment isolées des voies respiratoires des patients atteints de fibrose kystique lors d'infections bactériennes chroniques. Mon projet de doctorat a consisté à déterminer les bases moléculaires de la persistance des infections pulmonaires à S. aureus chez les patients atteints de fibrose kystique et, plus particulièrement, le rôle des SCVs dans l'établissement d'infections chroniques. Mes principaux efforts de recherche ont été dirigés vers la compréhension du rôle de gènes et de phénotypes influencés par le facteur de transcription sigma alternatif sigma B dont l'activité est accrue chez les SCVs. Les mécanismes moléculaires par lesquels ce facteur de transcription influence la formation de biofilm, la persistance à l'intérieur des cellules de l'hôte et l'infection proprement dite ont été étudiés. Je me suis aussi intéressé à la compréhension des différents facteurs environnementaux et mécanismes moléculaires favorisant la présence et la persistance de S. aureus dans les poumons des patients fibrokystiques. Mes efforts de recherche ont également été dirigés vers l'élaboration d'antibiothérapies alternatives permettant de combattre les infections chroniques à S. aureu

Cas9+ conditionally-immortalized macrophages as a tool for bacterial pathogenesis and beyond.

Macrophages play critical roles in immunity, development, tissue repair, and cancer, but studies of their function have been hampered by poorly-differentiated tumor cell lines and genetically-intractable primary cells. Here we report a facile system for genome editing in non-transformed macrophages by differentiating ER-Hoxb8 myeloid progenitors from Cas9-expressing transgenic mice. These conditionally immortalized macrophages (CIMs) retain characteristics of primary macrophages derived from the bone marrow yet allow for easy genetic manipulation and a virtually unlimited supply of cells. We demonstrate the utility of this system for dissection of host genetics during intracellular bacterial infection using two important human pathogens: Listeria monocytogenes and Mycobacterium tuberculosis

Evasion of autophagy mediated by Rickettsia surface protein OmpB is critical for virulence.

Rickettsia are obligate intracellular bacteria that evade antimicrobial autophagy in the host cell cytosol by unknown mechanisms. Other cytosolic pathogens block different steps of autophagy targeting, including the initial step of polyubiquitin-coat formation. One mechanism of evasion is to mobilize actin to the bacterial surface. Here, we show that actin mobilization is insufficient to block autophagy recognition of the pathogen Rickettsia parkeri. Instead, R. parkeri employs outer membrane protein B (OmpB) to block ubiquitylation of the bacterial surface proteins, including OmpA, and subsequent recognition by autophagy receptors. OmpB is also required for the formation of a capsule-like layer. Although OmpB is dispensable for bacterial growth in endothelial cells, it is essential for R. parkeri to block autophagy in macrophages and to colonize mice because of its ability to promote autophagy evasion in immune cells. Our results indicate that OmpB acts as a protective shield to obstruct autophagy recognition, thereby revealing a distinctive bacterial mechanism to evade antimicrobial autophagy