Hedging of American Options under Transaction Costs

International audienceWe consider a continuous-time model of financial market with proportional transaction costs. Our result is a dual description of the set of initial endowments of self-financing portfolios super replicating American - type contingent claim. The latter is a right-continuous adapted vector process describing the number of assets to be delivered at the exercise date. We introduce a specific class of price systems, called coherent, and show that the hedging endowments are those whose 'values' are larger than the expected weighted 'values' of the pay-off process for every coherent price system used for the 'evaluation' of the assets

Bactéries multirésistantes et voyage [Multidrug-resistant bacteria and travel]

Antimicrobial resistance is a global problem which affects also tropical countries. Travelers to these regions expose themselves to the risk of being colonised and infected with multidrug-resistant bacteria. The region visited, the occurrence of diarrhoea and the use of antibiotics are the principal risk factors leading to colonisation with multidrug-resistant Enterobacteriaceae, which can affect up to 80% of travellers. Colonisation with meticillin resistant Staphylococcus aureus and vancomycin resistant enterococci are often due to contacts with the health care system of the visited country. For the practitioner evaluating a patient returning from abroad it is important to consider the risk of infection with multidrug-resistant bacteriae. Screening for these bacteriae in the stool or by mucocutaneous swabs can be discussed in certain situations

Observational study on the consumption of recreational drugs and alcohol by Swiss travelers.

BACKGROUND: Studies carried out on specific travelers' groups such as students describe an increase in the consumption of alcohol and drugs during travel and vacation time. The present study investigates the risk behaviors (alcohol and drugs) in a general adult population in Switzerland travelling abroad who visited a travel clinic before departure. METHODS: This retrospective study was conducted in a travel clinic between January 2006 and December 2008. 14,496 patients came to the clinic for a pre-travel consultation. 3,537 of them answered a questionnaire about their life habits in Switzerland and during their last trip. The only exclusion criterion was an age inferior to 18 years old.The consumption habits of drugs and at-risk alcohol intake (8 standard drinks (SD) per week for women and 15 SD for men) was analyzed according to gender, sex, destination and profession. Predictors of adopting a risky behavior between habits in Switzerland and during their previous trip were also analyzed. RESULTS: 7% (229/3477) of participants declared having at-risk alcohol consumption in Switzerland and 14% (473/3275 [95% CI 13-16]) during their trip. 9% (332/3527) of the participants used drugs in Switzerland and 5% (178/3481) during their trip. Risk factors for at-risk alcohol consumption during a trip were: at-risk alcohol consumption in Switzerland (OR 31[95% CI 21-45]), smoking (1.7 [95% CI 1-2]), use of drugs in Switzerland (OR 2.2 [95% CI 2-3]), leisure travel (OR 1.6 [95% CI 1-2]) and managerial professions (OR 1.8 [95% CI 1-3]). Risk factors for the use of drugs during a trip were: alcohol consumption in Switzerland (OR 2.1 [95% CI 1-4]), smoking (OR 1.9 [95% CI 1-3]), and use of drugs in Switzerland (OR 29.7 [95% CI 19-45]). CONCLUSIONS: At-risk alcohol consumption and, to a lesser extent, use of drugs, affect a large number of travelers which expose them to health problems during a trip. Exploring the alcohol and drugs consumption patterns of people visiting a travel clinic should be part of the pre-travel routine consultation and would allow to identifying people who would benefit most from a specific prevention

The Grueneberg ganglion controls odor-driven food choices in mice under threat.

The ability to efficiently search for food is fundamental for animal survival. Olfactory messages are used to find food while being aware of the impending risk of predation. How these different olfactory clues are combined to optimize decision-making concerning food selection remains elusive. Here, we find that chemical danger cues drive the food selection in mice via the activation of a specific olfactory subsystem, the Grueneberg ganglion (GG). We show that a functional GG is required to decipher the threatening quality of an unfamiliar food. We also find that the increase in corticosterone, which is GG-dependent, enhances safe food preference acquired during social transmission. Moreover, we demonstrate that memory retrieval for food preference can be extinguished by activation of the GG circuitry. Our findings reveal a key function played by the GG in controlling contextual food responses and illustrate how mammalian organisms integrate environmental chemical stress to optimize decision-making

Vaccins de voyage : quel horizon ? [Travel vaccines: what is in the pipeline?]

While no vaccine is on the horizon to prevent traveler's diarrhea, progress has been made in the field of malaria and dengue fever. In both cases, the objective is not primarily the prevention among travelers but rather the reduction of morbidity and mortality in populations living in endemic areas. The immune mechanisms protecting against parasitosis are not well understood, which further complicates vaccine development. The fact that veterinary vaccines against the parasites causing cysticercosis and echinococcosis are available for animals, justifies a certain optimism that vaccines against parasitosis will also be available for humans in the future. We report on recent developments in dengue, malaria, schistosomiasis, and hookworm vaccines

Point prevalence study of antibiotic appropriateness and possibility of early discharge from hospital among patients treated with antibiotics in a Swiss University Hospital.

BACKGROUND The growing threat of multidrug resistant organisms have led to increasingly promote prudent and rational use of antimicrobials as well as early hospital discharge plan. Antibiotic stewardship programs (ASP) have been developed as multifaceted approaches to improve use of current antibiotics and are now widely applied through different strategies. Proactive interventions are still limited in Switzerland and data on antimicrobial appropriateness and early discharge strategies are lacking. We aimed to describe the opportunities of antibiotics prescriptions optimization at Lausanne University Hospital, Switzerland and evaluate the suitability for early discharge among patients receiving antibiotics. The need for outpatient medical structures was also assessed. METHODS We conducted a point prevalence survey of antibiotic prescriptions in adult medical and surgical units with exclusion of intermediate and intensive care units. All hospitalized patients receiving a systemic antibiotic on the day of evaluation were included. An infectious diseases specialist evaluated antimicrobial appropriateness and assessed suitability for discharge according to medical and nursing observations. The need of flexible additional outpatient facility for a close medical follow-up was evaluated concomitantly. RESULTS A total of 564 patients' files were reviewed. 182 (32%) patients received one or more systemic antibiotic: 62 (34%) as a prophylaxis and 120 (66%) as a treatment with or without concomitant prophylaxis. 37/62 (60%) patients receiving prophylaxis had no indication to continue the antibacterial. Regarding the patients treated with antibiotics, 69/120 (58%) presented at least one opportunity for treatment optimization, mainly interruption of treatment. A previous ID consultation was recorded for 55/120 (46%) patients, of whom 21 (38%) could have benefited from antimicrobial therapy optimization on the day of the point assessment. 9.2% patients were eligible for discharge of whom 64% could leave the hospital with a close outpatient follow-up for infectious issues. CONCLUSIONS This point prevalence study offers precious indicators for tailoring future antibiotic stewardship interventions that can be combined with early discharge. Any centre considering implementing ASP should conduct this type of analysis with a pragmatic approach to gain insight into local practices and needed resources

Setting up an outpatient parenteral antimicrobial therapy (OPAT) unit in Switzerland: review of the first 18 months of activity.

Outpatient parenteral antimicrobial therapy (OPAT) has been recognised as a useful, cost-effective and safe alternative to inpatient treatment, but no formal OPAT unit existed in Switzerland until recently. In December 2013 an OPAT unit was established at Lausanne University Hospital. We review here the experience of this new OPAT unit after 18 months of activity. Patient characteristics, clinical activities and outcomes were recorded prospectively. Need and acceptance was evaluated as number of OPAT courses administered and number of patients refusing OPAT. Safety and efficacy were evaluated as: (1) adverse events linked to antimicrobials and catheters, (2) re-admission to hospital, (3) rate of treatment failures and (4) mortality. Over 18 months, 179 courses of OPAT were administered. Acceptance was high with only four patients refusing OPAT. Urinary tract infections with resistant bacteria and musculoskeletal infections were the most common diagnoses. Self-administration of antibiotics using elastomeric pumps became rapidly the most frequently used approach. Sixteen patients presented with adverse events linked to antimicrobials and catheters. OPAT-related readmissions occurred in nine patients. The overall cure rate was 94 %. This study shows that OPAT is very well accepted by patients and medical staff, even in a setting which has not used this type of treatment approach until now. Self-administration using elastomeric pumps proved to be particularly useful, safe and efficient. OPAT offers a good alternative to hospitalisation for patients presenting with infections due to resistant bacteria that cannot be treated orally anymore and for difficult to treat infections

Food preference acquired by social transmission is altered by the absence of the olfactory marker protein in mice.

Food preference is conserved from the most primitive organisms to social animals including humans. A continuous integration of olfactory cues present both in food and in the different environmental and physiological contexts favors the intake of a given source of food or its avoidance. Remarkably, in mice, food preference can also be acquired by olfactory communication in-between conspecifics, a behavior known as the social transmission of food preference (STFP). STFP occurs when a mouse sniffs the breath of a conspecific who has previously eaten a novel food emitting specific odorants and will then develop a preference for this never encountered food. The efficient discrimination of odorants is performed by olfactory sensory neurons (OSNs). It is essential and supports many of the decision-making processes. Here, we found that the olfactory marker protein (OMP), an enigmatic protein ubiquitously expressed in all mature olfactory neurons, is involved in the fine regulation of OSNs basal activity that directly impacts the odorant discrimination ability. Using a previously described Omp null mouse model, we noticed that although odorants and their hedonic-associated values were still perceived by these mice, compensatory behaviors such as a higher number of sniffing events were displayed both in the discrimination of complex odorant signatures and in social-related contexts. As a consequence, we found that the ability to differentiate the olfactory messages carried by individuals such as those implicated in the social transmission of food preference were significantly compromised in Omp null mice. Thus, our results not only give new insights into the role of OMP in the fine discrimination of odorants but also reinforce the fundamental implication of a functional olfactory system for food decision-making

High Prevalence of Peripheral Arterial Disease in HIV-Infected Persons

Background. Atherosclerosis has been assessed in human immunodeficiency virus (HIV)-infected persons by using various methods. Peripheral arterial disease (PAD) has not been evaluated, however. We studied the cross-sectional prevalence of lower limb PAD in an HIV-infected population. Methods. PAD was assessed using the Edinburgh Claudication Questionnaire and by measuring the systolic ankle-brachial blood pressure index (ABI) at rest and after exercise. Patients with PAD were further evaluated by duplex scan of lower limb arteries. Results. Ninety-two consecutive HIV-infected patients were evaluated (23.9% women; mean age, 49.5 years; 61.9% current smokers). Claudication was reported by 15.2% of the patients. PAD was found in 20.7% of the patients: 9.8% had an abnormal ABI (25% decrease after exercise. Of the patients with PAD, 84.2% were investigated with duplex scan, all of whom had atherosclerotic occlusions or stenoses of the iliac or femoral arteries. Age, diabetes, smoking, and low CD4+ T lymphocyte counts were identified as independent predictors of PAD. Conclusions. The prevalence of symptomatic and asymptomatic PAD is high in the HIV-infected population and is much higher than expected (prevalence in the general population, ∼3% at 60 years). This study suggests the presence of an epidemic of PAD ∼20 years earlier in the HIV-infected than in the general population. Larger epidemiological studies are needed to better define risk factors and to evaluate whether PAD is associated with increased mortality, as it is in the general populatio