A Maximal Domain for Strategy-Proof and No-Vetoer Rules in the Multi-Object Choice Model

Following Barberà, Sonnenschein, and Zhou (1991, Econometrica 59, 595-609), we study rules (or social choice functions) through which agents select a subset from a set of objects. We investigate domains on which there exist nontrivial strategy-proof rules. We establish that the set of separable preferences is a maximal domain for the existence of rules satisfying strategyproofness and no-vetoer

mTOR Controls Ovarian Follicle Growth by Regulating Granulosa Cell Proliferation

We have shown that inhibition of mTOR in granulosa cells and ovarian follicles results in compromised granulosa proliferation and reduced follicle growth. Further analysis here using spontaneously immortalized rat granulosa cells has revealed that mTOR pathway activity is enhanced during M-phase of the cell cycle. mTOR specific phosphorylation of p70S6 kinase and 4E-BP, and expression of Raptor are all enhanced during M-phase. The predominant effect of mTOR inhibition by the specific inhibitor Rapamycin (RAP) was a dose-responsive arrest in the G1 cell cycle stage. The fraction of granulosa cells that continued to divide in the presence of RAP exhibited a dose-dependent increase in aberrant mitotic figures known as anaphase bridges. Strikingly, estradiol consistently decreased the incidence of aberrant mitotic figures. In mice treated with RAP, the mitotic index was reduced compared to controls, and a similar increase in aberrant mitotic events was noted. RAP injected during a superovulation regime resulted in a dose-dependent reduction in the numbers of eggs ovulated. Implications for the real-time regulation of follicle growth and dominance, including the consequences of increased numbers of aneuploid granulosa cells, are discussed

Efficiency and strategy-proofness in object assignment problems with multi-demand preferences

Consider the problem of allocating objects to agents and how much they should pay. Each agent has a preference relation over pairs of a set of objects and a payment. Preferences are not necessarily quasi-linear. Non-quasi-linear preferences describe environments where payments influence agents' abilities to utilize objects. This paper is to investigate the possibility of designing efficient and strategy-proof rules in such environments. A preference relation is single demand if an agent wishes to receive at most one object; it is multi demand if whenever an agent receives one object, an additional object makes him better off. We show that if a domain contains all the single demand preferences and at least one multi demand preference relation, and there are more agents than objects, then no rule satisfies efficiency, strategy-proofness, individual rationality, and no subsidy for losers on the domain

Functionally reversible impacts of disturbances on lake food webs linked to spatial and seasonal dependencies

Increasing human impact on the environment is causing drastic changes in disturbance regimes and how they prevail over time. Of increasing relevance is to further our understanding on biological responses to pulse disturbances (short duration) and how they interact with other ongoing press disturbances (constantly present). Because the temporal and spatial contexts of single experiments often limit our ability to generalize results across space and time, we conducted a modularized mesocosm experiment replicated in space (five lakes along a latitudinal gradient in Scandinavia) and time (two seasons, spring and summer) to generate general predictions on how the functioning and composition of multitrophic plankton communities (zoo-, phyto- and bacterioplankton) respond to pulse disturbances acting either in isolation or combined with press disturbances. As pulse disturbance, we used short-term changes in fish presence, and as press disturbance, we addressed the ongoing reduction in light availability caused by increased cloudiness and lake browning in many boreal and subarctic lakes. First, our results show that the top-down pulse disturbance had the strongest effects on both functioning and composition of the three trophic levels across sites and seasons, with signs for interactive impacts with the bottom-up press disturbance on phytoplankton communities. Second, community composition responses to disturbances were highly divergent between lakes and seasons: temporal accumulated community turnover of the same trophic level either increased (destabilization) or decreased (stabilization) in response to the disturbances compared to control conditions. Third, we found functional recovery from the pulse disturbances to be frequent at the end of most experiments. In a broader context, these results demonstrate that top-down, pulse disturbances, either alone or with additional constant stress upon primary producers caused by bottom-up disturbances, can induce profound but often functionally reversible changes across multiple trophic levels, which are strongly linked to spatial and temporal context dependencies. Furthermore, the identified dichotomy of disturbance effects on the turnover in community composition demonstrates the potential of disturbances to either stabilize or destabilize biodiversity patterns over time across a wide range of environmental conditions

Molecular markers of anti-malarial drug resistance in Lahj Governorate, Yemen: baseline data and implications

<p>Abstract</p> <p>Background</p> <p>This is an investigation of anti-malarial molecular markers coupled with a therapeutic efficacy test of chloroquine (CQ) against falciparum malaria in an area of unstable malaria in Lahj Governorate, Yemen. The study was aimed at assessment of therapeutic response to CQ and elucidation of baseline information on molecular markers for <it>Plasmodium falciparum </it>resistance against CQ and sulphadoxine/pyrimethamine (SP).</p> <p>Methods</p> <p>Between 2002 and 2003 the field test was conducted according to the standard WHO protocol to evaluate the therapeutic efficacy of CQ in 124 patients with falciparum malaria in an endemic area in Lahj Governorate in Yemen. Blood samples collected during this study were analysed for <it>P. falciparum </it>chloroquine resistance transporter gene (<it>pfcrt</it>)-76 polymorphisms, mutation <it>pfcrt-</it>S163R and the antifolate resistance-associated mutations dihydrofolate reductase (<it>dhfr</it>)-C59R and dihydropteroate synthase (<it>dhps</it>)-K540E. Direct DNA sequencing of the <it>pfcrt </it>gene from three representative field samples was carried out after DNA amplification of the 13 exons of the <it>pfcrt </it>gene.</p> <p>Results</p> <p>Treatment failure was detected in 61% of the 122 cases that completed the 14-day follow-up. The prevalence of mutant <it>pfcrt </it>T76 was 98% in 112 amplified pre-treatment samples. The presence of <it>pfcrt </it>T76 was poorly predictive of <it>in vivo </it>CQ resistance (PPV = 61.8%, 95% CI = 52.7-70.9). The prevalence of <it>dhfr </it>Arg-59 mutation in 99 amplified samples was 5%, while the <it>dhps </it>Glu-540 was not detected in any of 119 amplified samples. Sequencing the <it>pfcrt </it>gene confirmed that Yemeni CQ resistant <it>P. falciparum </it>carry the old world (Asian and African) CQ resistant haplotype CVIETSESI at positions 72,73,74,75,76,220,271, 326 and 371.</p> <p>Conclusion</p> <p>This is the first study to report baseline information on the characteristics and implications of anti-malarial drug resistance markers in Yemen. It is also the first report of the haplotype associated with CQR <it>P. falciparum </it>parasites from Yemen. Mutant <it>pfcrt</it>T76 is highly prevalent but it is a poor predictor of treatment failure in the study population. The prevalence of mutation <it>dhfr</it>Arg59 is suggestive of emerging resistance to SP, which is currently a component of the recommended combination treatment of falciparum malaria in Yemen. More studies on these markers are recommended for surveillance of resistance in the study area.</p

Prevalence of Staphylococcus spp. nasal colonization among doctors of podiatric medicine and associated risk factors in Spain

Abstract Background This study aimed to estimate the prevalence of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) nasopharyngeal carriage among Doctors of Podiatric Medicine (Podiatrists) and to determine the potential risk factors. Methods A cross-sectional study was carried out in 2016–2017 among 239 podiatrists in Spain. The presence of MSSA, MRSA, and MRSE was determined by microbiological analysis of nasal exudate and antimicrobial susceptibility was determined. Each podiatrist completed a questionnaire. The questionnaire comprised various parameters such as sex, age, podiatry experience duration, underlying diseases, prior antibiotic treatment, hospitalization during the last year, and use of a protective mask, an aspiration system, or gloves. Results The prevalence of MSSA, MRSA, and MRSE was 23.0%, 1.3%, and 23.8%, respectively. The MSSA prevalence was higher among podiatrists who did not use an aspiration system (32.3%) compared to those who did (19.3%; p = 0.0305), and among podiatrists with respiratory diseases (36.8%) compared to those without (20.8%; p = 0.0272). The MRSE prevalence was higher among men (33.7%) compared to women (8.6%; p = 0.0089), podiatrists aged ≥50 (38.5%) compared to ≤35 (17.8%; p = 0.0101), and podiatrists with ≥15 (39.3%) compared to ≤5 years of podiatry experience (12.5%; p = 0.0015). Among the S. aureus strains, 84.5% were resistant to penicillin, 22.4% to erythromycin, 20.7% to clindamycin, and 12.7% to mupirocin. The MRSE strains were resistant to penicillin (93.0%), erythromycin (78.9%), and mupirocin (73.7%). Conclusions The prevalence of S. aureus and S. epidermidis nasal carriage is low among Spanish podiatrists compared to other health professionals