Three essays on the psychology of investment and financial markets

Préface My thesis consists of three essays where I consider equilibrium asset prices and investment strategies when the market is likely to experience crashes and possibly sharp windfalls. Although each part is written as an independent and self contained article, the papers share a common behavioral approach in representing investors preferences regarding to extremal returns. Investors utility is defined over their relative performance rather than over their final wealth position, a method first proposed by Markowitz (1952b) and by Kahneman and Tversky (1979), that I extend to incorporate preferences over extremal outcomes. With the failure of the traditional expected utility models in reproducing the observed stylized features of financial markets, the Prospect theory of Kahneman and Tversky (1979) offered the first significant alternative to the expected utility paradigm by considering that people focus on gains and losses rather than on final positions. Under this setting, Barberis, Huang, and Santos (2000) and McQueen and Vorkink (2004) were able to build a representative agent optimization model which solution reproduced some of the observed risk premium and excess volatility. The research in behavioral finance is relatively new and its potential still to explore. The three essays composing my thesis propose to use and extend this setting to study investors behavior and investment strategies in a market where crashes and sharp windfalls are likely to occur. In the first paper, the preferences of a representative agent, relative to time varying positive and negative extremal thresholds are modelled and estimated. A new utility function that conciliates between expected utility maximization and tail-related performance measures is proposed. The model estimation shows that the representative agent preferences reveals a significant level of crash aversion and lottery-pursuit. Assuming a single risky asset economy the proposed specification is able to reproduce some of the distributional features exhibited by financial return series. The second part proposes and illustrates a preference-based asset allocation model taking into account investors crash aversion. Using the skewed t distribution, optimal allocations are characterized as a resulting tradeoff between the distribution four moments. The specification highlights the preference for odd moments and the aversion for even moments. Qualitatively, optimal portfolios are analyzed in terms of firm characteristics and in a setting that reflects real-time asset allocation, a systematic over-performance is obtained compared to the aggregate stock market. Finally, in my third article, dynamic option-based investment strategies are derived and illustrated for investors presenting downside loss aversion. The problem is solved in closed form when the stock market exhibits stochastic volatility and jumps. The specification of downside loss averse utility functions allows corresponding terminal wealth profiles to be expressed as options on the stochastic discount factor contingent on the loss aversion level. Therefore dynamic strategies reduce to the replicating portfolio using exchange traded and well selected options, and the risky stock.

Device-specific weighted T-score for two quantitative ultrasounds: operational propositions for the management of osteoporosis for 65 years and older women in Switzerland.

The World Health Organization (WHO) criteria for the diagnosis of osteoporosis are mainly applicable for dual X-ray absorptiometry (DXA) measurements at the spine and hip levels. There is a growing demand for cheaper devices, free of ionizing radiation such as promising quantitative ultrasound (QUS). In common with many other countries, QUS measurements are increasingly used in Switzerland without adequate clinical guidelines. The T-score approach developed for DXA cannot be applied to QUS, although well-conducted prospective studies have shown that ultrasound could be a valuable predictor of fracture risk. As a consequence, an expert committee named the Swiss Quality Assurance Project (SQAP, for which the main mission is the establishment of quality assurance procedures for DXA and QUS in Switzerland) was mandated by the Swiss Association Against Osteoporosis (ASCO) in 2000 to propose operational clinical recommendations for the use of QUS in the management of osteoporosis for two QUS devices sold in Switzerland. Device-specific weighted "T-score" based on the risk of osteoporotic hip fractures as well as on the prediction of DXA osteoporosis at the hip, according to the WHO definition of osteoporosis, were calculated for the Achilles (Lunar, General Electric, Madison, Wis.) and Sahara (Hologic, Waltham, Mass.) ultrasound devices. Several studies (totaling a few thousand subjects) were used to calculate age-adjusted odd ratios (OR) and area under the receiver operating curve (AUC) for the prediction of osteoporotic fracture (taking into account a weighting score depending on the design of the study involved in the calculation). The ORs were 2.4 (1.9-3.2) and AUC 0.72 (0.66-0.77), respectively, for the Achilles, and 2.3 (1.7-3.1) and 0.75 (0.68-0.82), respectively, for the Sahara device. To translate risk estimates into thresholds for clinical application, 90% sensitivity was used to define low fracture and low osteoporosis risk, and a specificity of 80% was used to define subjects as being at high risk of fracture or having osteoporosis at the hip. From the combination of the fracture model with the hip DXA osteoporotic model, we found a T-score threshold of -1.2 and -2.5 for the stiffness (Achilles) determining, respectively, the low- and high-risk subjects. Similarly, we found a T-score at -1.0 and -2.2 for the QUI index (Sahara). Then a screening strategy combining QUS, DXA, and clinical factors for the identification of women needing treatment was proposed. The application of this approach will help to minimize the inappropriate use of QUS from which the whole field currently suffers.

Prognostic importance of hyponatremia in patients with acute pulmonary embolism

Rapport de synthèse Enjeux et contexte: L'hyponatrémie est un trouble électrolytique fréquent et associé à un pronostic défavorable dans de nombreuses affections card iovascu lai res (1-5), pour lesquelles il est un marqueur de l'activation neurohumorale (6). Sa valeur pronostique chez les patients se présentant avec une emboîie pulmonaire était jusque là inconnue ; elle fait l'objet de la présente étude.Objectifs: Examiner chez les patients hospitalisés pour une embolie pulmonaire, les associations entre hyponatrémie et mortalité ainsi qu'avec le taux de réhospitalisation. Méthodes: Nous avons étudié les données de 13728 patients avec un diagnostic principal d'embolie pulmonaire provenant de 185 hôpitaux en Pennsylvanie (janvier 2000 à novembre 2002.) Nous avons utilisé un modèle de régression logistique afin d'établir l'association indépendante entre le niveau de sodium lors de la présentation aux urgences et la mortalité ainsi que le taux de ^hospitalisation durant 30 jours. Nous avons ajusté pour les caractéristiques du patient (race, assurance, sévérité de la maladie, usage de la thrombolyse) et de l'hôpital (région, taille, avec ou sans médecins en formation.)Résultats principaux: Une hyponatrémie (sodium £ 135 mmol/l) était présente chez 2907 patients (21.1%). Les patients avec un sodium >135, 130-135, et <130 mmol/l avaient une mortalité cumulée à 30 jours de 8.0%, 13.6%, et 28.5% (P <0.001), et un taux de réadmission de 11.8%, 15.6%, et 19.3% (P <0.001), respectivement. Comparés aux patients avec un sodium >135 mmol/l, les odd ratios ajustés concernant la mortalité étaient significativement plus important pour les patients avec un sodium compris entre 130 et 135 mmol/l (OR 1.53, 95% Cl: 1.33-1.76) ou <130 mmol/l (OR 3.26, 95% Cl: 2.48-4.29). Les odd ratios ajustés concernant la réhospitalisation étaient également augmentés pour les patients présentant un sodium entre 130 et 135 mmol/l (OR 1.28, 95% Cl: 1.12-1.46) ou <130 mmol/l (OR 1.44, 95% Cl: 1.02-2.02). Conclusions et perspectives: L'hyponatrémie est fréquente chez les patients se présentant avec une embolie pulmonaire, de plus elle est un prédicateur indépendant de la mortalité à court terme, ainsi que du taux de réhospitalisation. La natrémie est une information généralement disponible lors de l'établissement d'un pronostic. Bien que cette association soit compatible avec une activation neurohumorale, nous ne pouvons pas attester des mécanismes impliqués, du fait que notre étude ne donne pas d'informations sur d'autres étapes de la physiologie de cette association.

Externalizing disorders and substance use: empirically derived subtypes in a population-based sample of adults.

PURPOSE: Attention-deficit/hyperactivity disorder (ADHD), conduct disorder (CD), and oppositional defiant disorder (ODD) are common externalizing disorders of childhood. The common effects of these disorders on substance abuse need further investigation. The current study investigated the joint clusters of childhood/adolescence ADHD, CD, and ODD, and their influence on substance abuse/dependence in a population-based sample of adults. METHODS: The data were drawn from the PsyCoLaus study (n = 3,720) conducted in Lausanne, Switzerland. The population-based sample included 238 subjects meeting criteria for ADHD/ODD/CD diagnoses before the age of 15. Latent class analyses (LCA) were performed to derive comorbidity subtypes, which were subsequently characterized with respect to psychosocial correlates and substance use. RESULTS: The best fit in LCAs was achieved with three latent classes: an ADHD subtype (35.7 %); an externalizing multimorbid subtype (33.6 %) involving ODD, ADHD, and CD; and a third subtype with CD (30.7 %). The CD subtype showed the highest association with substance use. Apart from this, the externalizing multimorbid subtype was also significantly linked to substance use. The ADHD subtype had only elevated frequencies for alcohol dependence in comparison with subjects that had no history of ADHD, ODD, and CD during childhood or adolescence. Finally, important interactions between subtypes and sex were observed with regard to substance use. CONCLUSIONS: This study provides evidence showing that subtyping the externalizing disorders, ADHD, ODD and CD, along their comorbidity patterns leads to important differences regarding substance use. This could have implications for the etiology, prevention, and treatment of substance use disorders.

Hypertension and intra-operative incidents: a multicentre study of 125,000 surgical procedures in Swiss hospitals.

It is debated whether chronic hypertension increases the risk of cardiovascular incidents during anaesthesia. We studied all elective surgical operations performed in adults under general or regional anaesthesia between 2000 and 2004, in 24 hospitals collecting computerised clinical data on all anaesthetics since 1996. The focus was on cardiovascular incidents, though other anaesthesia-related incidents were also evaluated. Among 124,939 interventions, 27,881 (22%) were performed in hypertensive patients. At least one cardiovascular incident occurred in 7549 interventions (6% (95% CI 5.9-6.2%)). The average adjusted odds ratio of cardiovascular risk for chronic hypertension was 1.38 (95% CI 1.27-1.49). However, across hospitals, adjusted odd ratios varied from 0.41 up to 2.25. Hypertension did not increase the risk of other incidents. Hypertensive patients are still at risk of intra-operative cardiovascular incidents, while risk heterogeneity across hospitals, despite taking account of casemix and hospital characteristics, suggests variations in anaesthetic practices.

BlastR--fast and accurate database searches for non-coding RNAs.

We present and validate BlastR, a method for efficiently and accurately searching non-coding RNAs. Our approach relies on the comparison of di-nucleotides using BlosumR, a new log-odd substitution matrix. In order to use BlosumR for comparison, we recoded RNA sequences into protein-like sequences. We then showed that BlosumR can be used along with the BlastP algorithm in order to search non-coding RNA sequences. Using Rfam as a gold standard, we benchmarked this approach and show BlastR to be more sensitive than BlastN. We also show that BlastR is both faster and more sensitive than BlastP used with a single nucleotide log-odd substitution matrix. BlastR, when used in combination with WU-BlastP, is about 5% more accurate than WU-BlastN and about 50 times slower. The approach shown here is equally effective when combined with the NCBI-Blast package. The software is an open source freeware available from www.tcoffee.org/blastr.html.

Anterior ischemic optic neuropathy in eyes with optic disc drusen.

BACKGROUND: There have been anecdotal reports of anterior ischemic optic neuropathy (AION) occurring in eyes with optic disc drusen (ODD), but the clinical features of this condition have not been well characterized. OBJECTIVES: To better describe the clinical features of AION associated with ODD and to compare the clinical features of this condition with those of "garden variety" nonarteritic AION. METHODS: We reviewed the medical records of 20 patients who experienced an episode of AION in an eye with ODD. In 4 patients, both eyes were affected; thus, 24 eyes were studied. The diagnosis of ODD was made by ophthalmoscopic identification, orbital ultrasonography, or computed tomographic scanning. We recorded age, sex, vascular risk factors, symptoms, visual acuity, visual fields, and results of the follow-up examination in all patients. These findings were compared with data from previously reported series of patients with nonarteritic AION. RESULTS: Our 20 patients included 14 men and 6 women (age range, 18-69 years; mean, 49.4 years). Vascular risk factors were identified in 10 patients (50%). Three patients reported episodes of transient visual loss before their fixed deficit. The visual acuity at the initial examination was 20/60 or better in 15 (62%) of the 24 eyes; 8 had a visual acuity of 20/20. The predominant pattern of visual field loss was an altitudinal or arcuate defect in 19 (79%) and a centrocecal scotoma in 5 (21%) of the 24 eyes. There was subjective worsening of vision before the initial neuro-ophthalmic examination in 11 eyes (46%) and objective documentation of progression in 7 eyes (29%). The final visual acuity was 20/40 or better in 13 (62%) of 21 eyes and 20/200 or worse in 3 (14%) of 21 eyes. CONCLUSIONS: Our patients were strikingly similar to those with nonarteritic AION unassociated with drusen in regard to prevalence of vascular risk factors, pattern of visual field loss, and occurrence of a subsequent similar event in the fellow eye. In contrast, however, patients with ODD-AION were younger than those with nonarteritic AION, were more likely to report preceding episodes of transient visual obscuration, and enjoyed a more favorable visual outcome.

A topological invariant to predict the three-dimensional writhe of ideal configurations of knots and links.

We present herein a topological invariant of oriented alternating knots and links that predicts the three-dimensional (3D) writhe of the ideal geometrical configuration of the considered knot/link. The fact that we can correlate a geometrical property of a given configuration with a topological invariant supports the notion that the ideal configuration contains important information about knots and links. The importance of the concept of ideal configuration was already suggested by the good correlation between the 3D writhe of ideal knot configurations and the ensemble average of the 3D writhe of random configurations of the considered knots. The values of the new invariant are quantized: multiples of 4/7 for links with an odd number of components (including knots) and 2/7 plus multiples of 4/7 for links with an even number of components.

Saccharomyces cerevisiae, a tool to study the β-oxidation through the synthesis of polyhydroxyalkanoates

Summary Polyhydroxyalkanoates (PHAs) represent a family of polyesters naturally synthesized by a wide variety of bacteria. Through their thermoplastic and elastomeric qualities, together with their biodegradable and renewable properties, they are predicted to be a good alternative to the petroleum- derived plastics. Nevertheless, as PHA production costs using bacteria fermentation are still too high, PHA synthesis within eukaryotic systems, such as plants, has been elaborated. Although the costs were then efficiently lowered, the yield of PHAs produced remained low. In this study, Saccharomyces cerevisae has been used as another eukaryotic model in order to reveal the steps which limit PHA production. These cells express the PHA synthase of Pseudomonas aeruginosa and the PHAs obtained were analyzed to understand the flux of fatty acids towards and through the peroxisomal β-oxidation core cycle, generating the main substrate of the PHA synthase. When S. cerevisiae wild-type cells are grown in a media containing glucose as carbon source as well as fatty acids, the PHA monomer composition is largely influenced by the nature of the external fatty acid used. Thus, even-chain PHA monomers are generated from oleic acid (18:1Δ9cis) and odd- chain PHA monomers are generated from heptadecenoic acid (17:1Δ. 10 cis). Moreover, PHA synthesis is dependent on the first two enzymes of the 0-oxidation core cycle, the acyl-CoA oxidase and the multifunctional enzyme enoyl-CoA hydratase II / R-3-hydroxyacyl-CoA dehydrogenase. S. cerevisiae mutant cells growing on oleic or heptadecenoic acid and deficient in either the R-3- hydroxyacyl-CoA dehydrogenase or in the 3-ketothiolase activity, the last β-oxidation cycle steps, surprisingly contained PHAs of predominantly even-chain monomers. This is also noticed in wild- type and mutants grown on glucose or raffinose, indicating that the substrate used for PHA synthesis is generated from the degradation of intracellular short- and medium-chain fatty acids by the 3- oxidation cycle. Inhibition of fatty acid biosynthesis by cerulenin blocks the synthesis of PHAs from intracellular fatty acids but still enables the use of extracellular fatty acids for polymer production. Together, these results uncovered the existence of a substantial futile cycle whereby short- and medium-chain intermediates of the cytoplasmic fatty acid biosynthetic pathway are directed towards the peroxisomal β-oxidation pathway. In this thesis, no increase of the yield of PHA produced could be obtained. But the PHA synthesis confirmed the carbon flux into and through the β-oxidation core cycle and unveiled the existence of novel mechanisms. It is thus a good tool to study in vivo the flux of carbons in S. cerevisiae cells. Résumé Les polyhydroxyalkanoates (PHAs) sont une famille de polyesters naturellement synthétisés par un grand nombre de bactéries. Ayant des propriétés de thermoplastiques, d'élastomères et étant des ressources biodégradables et renouvelables, les PHAs représentent une bonne alternative aux plastiques dérivés du pétrole. Pour pallier aux coûts considérables de la production de PHAs par fermentation bactérienne, la synthèse de PHAs par des systèmes eucaryotes telles les plantes a été élaborée. Les coûts ont ainsi efficacement été diminués, mais le rendement de PHAs produits reste faible. Dans cette étude, Saccharomyces cerevisiae a été utilisé comme autre modèle eucaryote pour révéler les étapes limitantes de la production de PHAs. Les PHAs obtenus dans les cellules exprimant la F'HA synthase de Pseudomonas aeruginosa ont été analysés afin de comprendre le flux d'acides gras vers et à travers le cycle péroxisomal de la β-oxidation, principal producteur du substrat de la PHA synthase. Lorsque la souche S. cerevisiae de type sauvage se développe dans un milieu contenant du glucose et des acides gras, la composition des monomères de PHAs est influencée par la nature des acides gras extracellulaires. Ainsi, les monomères pairs sont générés par l'acide oléique (18:1Δ9cis), tandis que les impairs le sont par l'acide heptadécénoïque (17:1Δ10cis). La synthèse de PHAs est dépendante des deux premières enzymes de la β-oxidation; l'acyl-CoA oxidase et l'enzyme multifonctionnelle enoyl-CoA hydratase II / R-3-hydroxyacyl-CoA déshydrogénase. Les souches mutantes ne possédant pas les activités de la R-3-hydroxyacyl-CoA déshydrogénase ou de la 3- ketothiolase contiennent, en présence d'acide oléique ou heptadécénoïque, des PHAs composés essentiellement de monomères pairs. Cela a également été observé en présence de glucose ou de raffinose uniquement. Le substrat utilisé pour la synthèse de PHAs a ainsi été généré par la dégradation d'acides gras intracellulaires à chaîne courte et moyenne via le cycle de la β-oxidation. L'inhibition de la synthèse d'acides gras par la cérulénine a bloqué la synthèse de PHAs par les acides gras internes. Ces résultats ont révélés l'existence d'un cycle futile par lequel des intermédiaires à chaîne courte et moyenne de la synthèse cytoplasmique d'acides gras sont dirigés vers le cycle péroxisomal de la β-oxidation. Dans cette étude, le rendement de PHAs produits reste inchangé, mais l'analyse des PHAs permet de confirmer le flux de carbones vers et à travers le cycle péroxisomal de la β-oxidation et l'existence de nouveaux méchanismes a été dévoilée. Cette synthèse s'avère être un bon outil pour étudier in vivo le flux de carbones dans les cellules de S. cerevisiae.

Metabolically healthy obesity: different prevalences using different criteria.

To estimate the prevalence of metabolically healthy obesity (MHO) according to different definitions. Population-based sample of 2803 women and 2557 men participated in the study. Metabolic abnormalities were defined using six sets of criteria, which included different combinations of the following: waist; blood pressure; total, high-density lipoprotein or low-density lipoprotein-cholesterol; triglycerides; fasting glucose; homeostasis model assessment; high-sensitivity C-reactive protein; personal history of cardiovascular, respiratory or metabolic diseases. For each set, prevalence of MHO was assessed for body mass index (BMI); waist or percent body fat. Among obese (BMI 30 kg/m(2)) participants, prevalence of MHO ranged between 3.3 and 32.1% in men and between 11.4 and 43.3% in women according to the criteria used. Using abdominal obesity, prevalence of MHO ranged between 5.7 and 36.7% (men) and 12.2 and 57.5% (women). Using percent body fat led to a prevalence of MHO ranging between 6.4 and 43.1% (men) and 12.0 and 55.5% (women). MHO participants had a lower odd of presenting a family history of type 2 diabetes. After multivariate adjustment, the odds of presenting with MHO decreased with increasing age, whereas no relationship was found with gender, alcohol consumption or tobacco smoking using most sets of criteria. Physical activity was positively related, whereas increased waist was negatively related with BMI-defined MHO. MHO prevalence varies considerably according to the criteria used, underscoring the need for a standard definition of this metabolic entity. Physical activity increases the likelihood of presenting with MHO, and MHO is associated with a lower prevalence of family history of type 2 diabetes.

TBS discrimine les femmes avec ostéoporose fracturaire des femmes non ostéoporotiques indépendamment de la DMO, de l'âge et de l'IMC : Etude de la cohorte Ostéo-Mobile Vaud

Introduction. - « Ostéo-Mobile Vaud » est un projet pilote visant àinformer et promouvoir les mesures générales de prévention del'ostéoporose chez les femmes vaudoises de 60 ans et plus. Son butest également d'évaluer le risque de fracture dans cette populationen associant les facteurs de risque cliniques, la mesure de la DMOpar DXA de la colonne lombaire et du fémur proximal (Hologic Discovery),la recherche des fractures vertébrales préexistantes parVFA et une appréciation de la « qualité osseuse » par TBS. Une phaseprospective de 5 ans est prévue. Le Trabecular Bone Score (TBS) estun procédé qui consiste à appliquer un traitement informatique àl'image 2D de projection de la DXA basé sur la quantification desvariations locales de niveaux de gris. Un modèle mathématiquerelie le paramètre TBS avec des paramètres de microarchitecture 3Dtels la connectivité 3D, le nombre de travées et l'espace inter-trabéculaire.Ce modèle fait de TBS une mesure indirecte de microarchitectureosseuse.Résultats. - Fin juillet 2011, 510 femmes de ± 67 ans, IMC ± 26 kg/m2,ont été évaluées. Une ou plusieurs fractures de fragilité ont été rapportéeschez 72 femmes, parmi lesquelles 39 avec fractures vertébrales.TBS diminue avec l'âge (-0.005 par année, p < 0,001) etdiminue en fonction de l'IMC (- 0,011 par kg/m2, p < 0,001). La corrélationentre TBS et la DMO de la colonne lombaire est faible(r = 0,4, p < 0,001) et un grand pourcentage de la variabilité du TBSest indépendant de la DMO (> 84%). TBS discrimine les femmes avecfractures vertébrales des femmes sans fracture vertébrale et lesfemmes avec OP clinique (fractures de fragilité) de celles sans OPclinique. Ce pouvoir discriminatif est indépendant de la DMO de lacolonne lombaire ou du T-score le plus bas, après ajustement pourl'âge et l'IMC.Odd ratio (OR, 95 % IC) pour une diminution d'une déviation standarddu TBS, ajusté pour l'âge, l'IMC et la mesure de DMO :Conclusion. - TBS représente une plus-value par rapport à la DMOdans l'appréciation du risque de fracture chez les femmes vaudoisesde 60 ans et plus.

Futile cycling of intermediates of fatty acid biosynthesis toward peroxisomal beta-oxidation in Saccharomyces cerevisiae.

The flux of fatty acids toward beta-oxidation was analyzed in Saccharomyces cerevisiae by monitoring polyhydroxyalkanoate synthesis in the peroxisome from the polymerization, by a bacterial polyhydroxyalkanoate synthase, of the beta-oxidation intermediates 3-hydroxyacyl-CoAs. Synthesis of polyhydroxyalkanoate was dependent on the beta-oxidation enzymes acyl-CoA oxidase and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase multifunctional protein, which are involved in generating 3-hydroxyacyl-CoAs, and on the peroxin PEX5, which is involved in the import of proteins into the peroxisome. In wild type cells grown in media containing fatty acids, the polyhydroxyalkanoate monomer composition was largely influenced by the nature of the external fatty acid, such that even-chain monomers are generated from oleic acid and odd-chain monomers are generated from heptadecenoic acid. In contrast, polyhydroxyalkanoate containing predominantly 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate was synthesized in a mutant deficient in the peroxisomal 3-ketothiolase (fox3 Delta 0) growing either on oleic acid or heptadecenoic acid as well as in wild type and fox3 Delta 0 mutants grown on glucose or raffinose, indicating that 3-hydroxyacyl-CoAs used for polyhydroxyalkanoate synthesis were generated from the degradation of intracellular short- and medium-chain fatty acids by the beta-oxidation cycle. Inhibition of fatty acid biosynthesis with cerulenin blocked the synthesis of polyhydroxyalkanoate from intracellular fatty acids but still enabled the use of extracellular fatty acids for polymer production. Mutants affected in the synthesis of lipoic acid showed normal polyhydroxyalkanoate synthesis capacity. Together, these results uncovered the existence of a substantial futile cycle whereby short- and medium-chain intermediates of the cytoplasmic fatty acid biosynthetic pathway are directed toward the peroxisomal beta-oxidation pathway.

Consistency and population sensitivity properties in marriage and Rrommate markets

We consider one-to-one matching markets in which agents can either be matched as pairs or remain single. In these so-called roommate markets agents are consumers and resources at the same time. Klaus (Games Econ Behav 72:172-186, 2011) introduced two new "population sensitivity" properties that capture the effect newcomers have on incumbent agents: competition sensitivity and resource sensitivity. On various roommate market domains (marriage markets, no-odd-rings roommate markets, solvable roommate markets),we characterize the core using either of the population sensitivity properties in addition to weak unanimity and consistency. On the domain of all roommate markets, we obtain two associated impossibility results.

Diagnostic performance of Fluorine-18-Fluorodeoxyglucose positron emission tomography in the assessment of pleural abnormalities in cancer patients: A systematic review and a meta-analysis.

OBJECTIVE: To systematically review and meta-analyze published data about the diagnostic performance of Fluorine-18-Fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and PET/computed tomography (PET/CT) in the assessment of pleural abnormalities in cancer patients. METHODS: A comprehensive literature search of studies published through June 2013 regarding the role of (18)F-FDG-PET and PET/CT in evaluating pleural abnormalities in cancer patients was performed. All retrieved studies were reviewed and qualitatively analyzed. Pooled sensitivity, specificity, positive and negative likelihood ratio (LR+ and LR-) and diagnostic odd ratio (DOR) of (18)F-FDG-PET or PET/CT on a per patient-based analysis were calculated. The area under the summary ROC curve (AUC) was calculated to measure the accuracy of these methods in the assessment of pleural abnormalities. Sub-analyses considering (18)F-FDG-PET/CT and patients with lung cancer only were carried out. RESULTS: Eight studies comprising 360 cancer patients (323 with lung cancer) were included. The meta-analysis of these selected studies provided the following results: sensitivity 86% [95% confidence interval (95%CI): 80-91%], specificity 80% [95%CI: 73-85%], LR+ 3.7 [95%CI: 2.8-4.9], LR- 0.18 [95%CI: 0.09-0.34], DOR 27 [95%CI: 13-56]. The AUC was 0.907. No significant improvement considering PET/CT studies only and patients with lung cancer was found. CONCLUSIONS: (18)F-FDG-PET and PET/CT demonstrated to be useful diagnostic imaging methods in the assessment of pleural abnormalities in cancer patients, nevertheless possible sources of false-negative and false-positive results should be kept in mind. The literature focusing on the use of (18)F-FDG-PET and PET/CT in this setting remains still limited and prospective studies are needed.

Simultaneous Mendelian and clonal genome transmission in a sexually reproducing, all-triploid vertebrate.

Meiosis in triploids faces the seemingly insuperable difficulty of dividing an odd number of chromosome sets by two. Triploid vertebrates usually circumvent this problem through either asexuality or some forms of hybridogenesis, including meiotic hybridogenesis that involve a reproductive community of different ploidy levels and genome composition. Batura toads (Bufo baturae; 3n = 33 chromosomes), however, present an all-triploid sexual reproduction. This hybrid species has two genome copies carrying a nucleolus-organizing region (NOR+) on chromosome 6, and a third copy without it (NOR-). Males only produce haploid NOR+ sperm, while ova are diploid, containing one NOR+ and one NOR- set. Here, we conduct sibship analyses with co-dominant microsatellite markers so as (i) to confirm the purely clonal and maternal transmission of the NOR- set, and (ii) to demonstrate Mendelian segregation and recombination of the NOR+ sets in both sexes. This new reproductive mode in vertebrates ('pre-equalizing hybrid meiosis') offers an ideal opportunity to study the evolution of non-recombining genomes. Elucidating the mechanisms that allow simultaneous transmission of two genomes, one of Mendelian, the other of clonal inheritance, might shed light on the general processes that regulate meiosis in vertebrates.