Sequential screening

We present a model of price discrimination where a monopolistfaces a consumer who is privately informed about thedistribution of his valuation for an indivisible unit ofgood but has yet to learn privately the actual valuation.The monopolist sequentially screens the consumer with amenu of contracts:the consumer self-selects once by choosing a contract andthen self-selects again when he learns the actual valuation. A deterministic sequential mechanism is a menu of refundcontracts, each consisting of an advance payment and a refundamount in case of no consumption, but sequential mechanismsmay involve randomization.We characterize the optimal sequential mechanism when someconsumer types are more eager in the sense of first-orderstochastic dominance, and when some types face greatervaluation uncertainty in the sense of mean-preserving-spread.We show that it can be optimal to subsidize consumer typeswith smaller valuation uncertainty (through low refund, as inairplane ticket pricing) in order to reduce the rent to thosewith greater uncertainty. The size of distortion depends bothon the type distribution and on how informative the consumer'sinitial private knowledge is about his valuation, but noton how much he initially knows about the valuation per se.

A zero-delay sequential scheme for lossy coding of individual sequences

We consider adaptive sequential lossy coding of bounded individual sequences when the performance is measured by the sequentially accumulated mean squared distortion. Theencoder and the decoder are connected via a noiseless channel of capacity $R$ and both are assumed to have zero delay. No probabilistic assumptions are made on how the sequence to be encoded is generated. For any bounded sequence of length $n$, the distortion redundancy is defined as the normalized cumulative distortion of the sequential scheme minus the normalized cumulative distortion of the best scalarquantizer of rate $R$ which is matched to this particular sequence. We demonstrate the existence of a zero-delay sequential scheme which uses common randomization in the encoder and the decoder such that the normalized maximum distortion redundancy converges to zero at a rate $n^{-1/5}\log n$ as the length of the encoded sequence $n$ increases without bound.

Grazing patterns of copepods in the upwelling system off Peru

Estudio de la cantidad de alimento ingerido para tres generos de copepodos con el fin de determinar la profundidad y la hora del día que se da el máximo y mínimo de actividad alimentaria.

External morphology of the adult of Dynamine postverta (Cramer) (Lepidoptera, Nymphalidae, Biblidinae) and patterns of morphological similarity among species from eight tribes of Nymphalidae

External morphology of the adult of Dynamine postverta (Cramer) (Lepidoptera, Nymphalidae, Biblidinae) and patterns of morphological similarity among species from eight tribes of Nymphalidae. The external structure of the integument of Dynamine postverta postverta (Cramer, 1779) is based on detailed morphological drawings and scanning electron microscopy. The data are compared with other species belonging to eight tribes of Nymphalidae, to assist future studies on the taxonomy and systematics of Neotropical Biblidinae.

Outcome and patterns of failure in testicular lymphoma: a multicenter Rare Cancer Network study.

PURPOSE: To assess the outcome and patterns of failure in patients with testicular lymphoma treated by chemotherapy (CT) and/or radiation therapy (RT). METHODS AND MATERIALS: Data from a series of 36 adult patients with Ann Arbor Stage I (n = 21), II (n = 9), III (n = 3), or IV (n = 3) primary testicular lymphoma, consecutively treated between 1980 and 1999, were collected in a retrospective multicenter study by the Rare Cancer Network. Median age was 64 years (range: 21-91 years). Full staging workup (chest X-ray, testicular ultrasound, abdominal ultrasound, and/or thoracoabdominal computer tomography, bone marrow assessment, full blood count, lactate dehydrogenase, and cerebrospinal fluid evaluation) was completed in 18 (50%) patients. All but one patient underwent orchidectomy, and spermatic cord infiltration was found in 9 patients. Most patients (n = 29) had CT, consisting in most cases of cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) with (n = 17) or without intrathecal CT. External RT was delivered to scrotum alone (n = 12) or testicular, iliac, and para-aortic regions (n = 8). The median RT dose was 31 Gy (range: 20-44 Gy) in a median of 17 fractions (10-24), using a median of 1.8 Gy (range: 1.5-2.5 Gy) per fraction. The median follow-up period was 42 months (range: 6-138 months). RESULTS: After a median period of 11 months (range: 1-76 months), 14 patients presented lymphoma progression, mostly in the central nervous system (CNS) (n = 8). Among the 17 patients who received intrathecal CT, 4 had a CNS relapse (p = NS). No testicular, iliac, or para-aortic relapse was observed in patients receiving RT to these regions. The 5-year overall, lymphoma-specific, and disease-free survival was 47%, 66%, and 43%, respectively. In univariate analyses, statistically significant factors favorably influencing the outcome were early-stage and combined modality treatment. Neither RT technique nor total dose influenced the outcome. Multivariate analysis revealed that the most favorable independent factors predicting the outcome were younger age, early-stage disease, and combined modality treatment. CONCLUSIONS: In this multicenter retrospective study, CNS was found to be the principal site of relapse, and no extra-CNS lymphoma progression was observed in the irradiated volumes. More effective CNS prophylaxis, including combined modalities, should be prospectively explored in this uncommon site of extranodal lymphoma.

Female-biased dispersal in the monogamous mammal Crocidura russula: evidence from field data and microsatellite patterns.

We investigated dispersal patterns in the monogamous Crocidura russula, based both on direct field observations (mark-recapture data) and on genetic analyses (microsatellite loci). Natal dispersal was found to be low. Most juveniles settled within their natal territory or one immediately adjacent. Migration rate was estimated to two individuals per year and per population. The correlation between genetic and geographical distances over a 16 km transect implies that migration occurs over short ranges. Natal dispersal was restricted to first-litter juveniles weaned in early May; this result suggests a direct dependence of dispersal on reproductive opportunities. Natal dispersal was highly female biased, a pattern unusual among mammals. Its association with monogamy provides support for the resource-competition model of dispersal. Our results demonstrate that a state-biased dispersal can be directly inferred from microsatellite genotype distributions, which opens new perspectives for empirical studies in this area.

Contrasting patterns of insecticide resistance and knockdown resistance (kdr) in Aedes aegypti populations from Jacarezinho (Brazil) after a Dengue Outbreak

ABSTRACT After a dengue outbreak, the knowledge on the extent, distribution and mechanisms of insecticide resistance is essential for successful insecticide-based dengue control interventions. Therefore, we evaluated the potential changes to insecticide resistance in natural Aedes aegypti populations to Organophosphates (OP) and Pyrethroids (PY) after chemical vector control interventions. After a Dengue outbreak in 2010, A. aegypti mosquitoes from the urban area of Jacarezinho (Paraná, Brazil) were collected in 2011 and 2012. Insecticide resistance to OP Temephos was assessed in 2011 and 2012 by dose–response bioassays adopting WHO-based protocols. Additionally, in both sampling, PY resistance was also investigated by the Val1016Ile mutation genotyping. In 2011, a random collection of mosquitoes was carried out; while in 2012, the urban area was divided into four regions where mosquitoes were sampled randomly. Bioassays conducted with larvae in 2011 (82 ± 10%; RR95 = 3.6) and 2012 (95 ± 3%; RR95 = 2.5) indicated an incipient altered susceptibility to Temephos. On the other hand, the Val1016IIe mutation analysis in 2011, presented frequencies of the 1016Ilekdr allele equal to 80%. Nevertheless, in 2012, when the urban area of Jacarezinho was analyzed as a single unit, the frequency of the mutant allele was 70%. Additionally, the distribution analysis of the Val1016Ile mutation in 2012 showed the mutant allele frequencies ≥60% in all regions. These outcomes indicated the necessity of developing alternative strategies such as insecticide rotations for delaying the evolution of resistance.

Phase 3 randomized trial on larynx preservation comparing sequential vs alternating chemotherapy and radiotherapy.

BACKGROUND: Both induction chemotherapy followed by irradiation and concurrent chemotherapy and radiotherapy have been reported as valuable alternatives to total laryngectomy in patients with advanced larynx or hypopharynx cancer. We report results of the randomized phase 3 trial 24954 from the European Organization for Research and Treatment of Cancer. METHODS: Patients with resectable advanced squamous cell carcinoma of the larynx (tumor stage T3-T4) or hypopharynx (T2-T4), with regional lymph nodes in the neck staged as N0-N2 and with no metastasis, were randomly assigned to treatment in the sequential (or control) or the alternating (or experimental) arm. In the sequential arm, patients with a 50% or more reduction in primary tumor size after two cycles of cisplatin and 5-fluorouracil received another two cycles, followed by radiotherapy (70 Gy total). In the alternating arm, a total of four cycles of cisplatin and 5-fluorouracil (in weeks 1, 4, 7, and 10) were alternated with radiotherapy with 20 Gy during the three 2-week intervals between chemotherapy cycles (60 Gy total). All nonresponders underwent salvage surgery and postoperative radiotherapy. The Kaplan-Meier method was used to obtain time-to-event data. RESULTS: The 450 patients were randomly assigned to treatment (224 to the sequential arm and 226 to the alternating arm). Median follow-up was 6.5 years. Survival with a functional larynx was similar in sequential and alternating arms (hazard ratio of death and/or event = 0.85, 95% confidence interval = 0.68 to 1.06), as were median overall survival (4.4 and 5.1 years, respectively) and median progression-free interval (3.0 and 3.1 years, respectively). Grade 3 or 4 mucositis occurred in 64 (32%) of the 200 patients in the sequential arm who received radiotherapy and in 47 (21%) of the 220 patients in the alternating arm. Late severe edema and/or fibrosis was observed in 32 (16%) patients in the sequential arm and in 25 (11%) in the alternating arm. CONCLUSIONS: Larynx preservation, progression-free interval, and overall survival were similar in both arms, as were acute and late toxic effects.

Dynamic social representations of the 2009 H1N1 pandemic: Shifting patterns of sense-making and blame

We investigate dynamics of public perceptions of the 2009 H1N1 influenza pandemic to understand changing patterns of sense-making and blame regarding the outbreak of emerging infectious diseases. We draw on social representation theory combined with a dramaturgical perspective to identify changes in how various collectives are depicted over the course of the pandemic, according to three roles: heroes, villains and victims. Quantitative results based on content analysis of three cross-sectional waves of interviews show a shift from mentions of distant collectives (e.g., far-flung countries) at Wave 1 to local collectives (e.g., risk groups) as the pandemic became of more immediate concern (Wave 2) and declined (Wave 3). Semi-automated content analysis of media coverage shows similar results. Thematic analyses of the discourse associated with collectives revealed that many were consistently perceived as heroes, villains and victims.

Patterns of convergence and divergence in the euro area

We study the extent of macroeconomic convergence/divergence among euro area countries. Our analysis focuses on four variables (unemployment, inflation, relative prices and the current account), and seeks to uncover the role played by monetary union as a convergence factor by using non-euro developed economies and the pre-EMU period as control samples.

Factors associated with comorbidity patterns in full and partial PTSD: Findings from the PsyCoLaus study.

Subtypes of comorbid conditions and their associated trauma and clinical characteristics in full and partial PTSD were examined. Data from 289 subjects from the general population that met criteria for full or partial PTSD were analyzed. Latent class analyses (LCA) were performed to derive homogeneous patterns of DSM-IV Axis-I disorders and anti-social personality comorbid to PTSD. Logistic regression models were conducted to characterize these classes by trauma-related and clinical features. The LCA revealed three classes: (1) low comorbidity; (2) high comorbidity with primarily substance-related disorders and a higher proportion of males; and (3) more severe PTSD-symptomatology and higher comorbid anxiety disorders and depression, almost entirely represented by females. Exposure to sexual abuse was more likely in the substance-dependent class and contributed strongly to the distinction between classes. Affective disorders tended to precede the onset of PTSD in the substance-dependent class, whereas phobias were more likely to follow PTSD in the depressed-anxious class. Posttrauma onset of alcohol use disorders in the substance dependent class confirmed the self-medication hypothesis. The three classes of comorbidity and their sequence of onset with PTSD suggest different mechanisms involved in their development. Our findings suggest that PTSD-related comorbidity subtypes also apply to individuals with partial PTSD.