967 resultados para Railroad safety, Bayesian methods, Accident modification factor, Countermeasure selection


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The HIV-1 subtype C has spread efficiently in the southern states of Brazil (Rio Grande do Sul, Santa Catarina and Parana). Phylogeographic studies indicate that the subtype C epidemic in southern Brazil was initiated by the introduction of a single founder virus population at some time point between 1960 and 1980, but little is known about the spatial dynamics of viral spread. A total of 135 Brazilian HIV-1 subtype C pol sequences collected from 1992 to 2009 at the three southern state capitals (Porto Alegre, Florianopolis and Curitiba) were analyzed. Maximum-likelihood and Bayesian methods were used to explore the degree of phylogenetic mixing of subtype C sequences from different cities and to reconstruct the geographical pattern of viral spread in this country region. Phylogeographic analyses supported the monophyletic origin of the HIV-1 subtype C clade circulating in southern Brazil and placed the root of that clade in Curitiba (Parana state). This analysis further suggested that Florianopolis (Santa Catarina state) is an important staging post in the subtype C dissemination displaying high viral migration rates from and to the other cities, while viral flux between Curitiba and Porto Alegre (Rio Grande do Sul state) is very low. We found a positive correlation (r(2) = 0.64) between routine travel and viral migration rates among localities. Despite the intense viral movement, phylogenetic intermixing of subtype C sequences from different Brazilian cities is lower than expected by chance. Notably, a high proportion (67%) of subtype C sequences from Porto Alegre branched within a single local monophyletic sub-cluster. These results suggest that the HIV-1 subtype C epidemic in southern Brazil has been shaped by both frequent viral migration among states and in situ dissemination of local clades.

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We report the measurement of direct photons at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/c < pT < 22 GeV/c, using a statistical method to subtract decay photons from the inclusive photon sample. The direct photon nuclear modification factor R-AA was calculated as a function of p(T) for different Au + Au collision centralities using the measured p + p direct photon spectrum and compared to theoretical predictions. R-AA was found to be consistent with unity for all centralities over the entire measured pT range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R-AA from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.

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The ALICE Collaboration has measured the inclusive production of muons from heavy-flavor decays at forward rapidity, 2.5 < y < 4, in pp and Pb-Pb collisions at root s(NN) = 2.76 TeV. The p(t)-differential inclusive cross section of muons from heavy-flavor decays in pp collisions is compared to perturbative QCD calculations. The nuclear modification factor is studied as a function of p(t) and collision centrality. A weak suppression is measured in peripheral collisions. In the most central collisions, a suppression of a factor of about 3-4 is observed in 6 < p(t) < 10 GeV/c. The suppression shows no significant p(t) dependence.

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Background: Human respiratory syncytial virus (HRSV) is one of the major etiologic agents of respiratory tract infections among children worldwide. Methodology/Principal Findings: Here through a comprehensive analysis of the two major HRSV groups A and B (n = 1983) which comprise of several genotypes, we present a complex pattern of population dynamics of HRSV over a time period of 50 years (1956-2006). Circulation pattern of HRSV revealed a series of expansions and fluctuations of co-circulating lineages with a predominance of HRSVA. Positively selected amino acid substitutions of the G glycoprotein occurred upon population growth of GB3 with a 60-nucleotide insertion (GB3 Insert), while other genotypes acquired substitutions upon both population growth and decrease, thus possibly reflecting a role for immune selected epitopes in linkage to the traced substitution sites that may have important relevance for vaccine design. Analysis evidenced the co-circulation and predominance of distinct HRSV genotypes in Brazil and suggested a year-round presence of the virus. In Brazil, GA2 and GA5 were the main culprits of HRSV outbreaks until recently, when the GB3 Insert became highly prevalent. Using Bayesian methods, we determined the dispersal patterns of genotypes through several inferred migratory routes. Conclusions/Significance: Genotypes spread across continents and between neighboring areas. Crucially, genotypes also remained at any given region for extended periods, independent of seasonal outbreaks possibly maintained by re-infecting the general population.

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The ALICE experiment has measured the inclusive J/psi production in Pb-Pb collisions at root s(NN) = 2.76 TeV down to zero transverse momentum in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/psi yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%-80% most central collisions, is 0.545 +/- 0.032(stat) +/- 0.083dsyst_ and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/psi production from charm quarks in a deconfined partonic phase can describe our data.

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The PHENIX experiment has measured electrons and positrons at midrapidity from the decays of hadrons containing charm and bottom quarks produced in d + Au and p + p collisions at root S-NN = 200 GeV in the transverse-momentum range 0.85 <= p(T)(e) <= 8.5 GeV/c. In central d + Au collisions, the nuclear modification factor R-dA at 1.5 < p(T) < 5 GeV/c displays evidence of enhancement of these electrons, relative to those produced in p + p collisions, and shows that the mass-dependent Cronin enhancement observed at the Relativistic Heavy Ion Collider extends to the heavy D meson family. A comparison with the neutral-pion data suggests that the difference in cold-nuclear-matter effects on light- and heavy-flavor mesons could contribute to the observed differences between the pi(0) and heavy-flavor-electron nuclear modification factors R-AA. DOI: 10.1103/PhysRevLett.109.242301

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The production of the prompt charm mesons D-0, D+, D*(+), and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at the LHC, at a centre-of-mass energy root s(NN) = 2.76 TeV per nucleon-nucleon collision. The p(t)-differential production yields in the range 2 < p(t) < 16 GeV/c at central rapidity, vertical bar y vertical bar < 0.5, were used to calculate the nuclear modification factor R-AA with respect to a proton-proton reference obtained from the cross section measured at root s = 7 TeV and scaled to root s = 2.76 TeV. For the three meson species, R-AA shows a suppression by a factor 3-4, for transverse momenta larger than 5 GeV/c in the 20% most central collisions. The suppression is reduced for peripheral collisions.

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This research has been triggered by an emergent trend in customer behavior: customers have rapidly expanded their channel experiences and preferences beyond traditional channels (such as stores) and they expect the company with which they do business to have a presence on all these channels. This evidence has produced an increasing interest in multichannel customer behavior and it has motivated several researchers to study the customers’ channel choices dynamics in multichannel environment. We study how the consumer decision process for channel choice and response to marketing communications evolves for a cohort of new customers. We assume a newly acquired customer’s decisions are described by a “trial” model, but the customer’s choice process evolves to a “post-trial” model as the customer learns his or her preferences and becomes familiar with the firm’s marketing efforts. The trial and post-trial decision processes are each described by different multinomial logit choice models, and the evolution from the trial to post-trial model is determined by a customer-level geometric distribution that captures the time it takes for the customer to make the transition. We utilize data for a major retailer who sells in three channels – retail store, the Internet, and via catalog. The model is estimated using Bayesian methods that allow for cross-customer heterogeneity. This allows us to have distinct parameters estimates for a trial and an after trial stages and to estimate the quickness of this transit at the individual level. The results show for example that the customer decision process indeed does evolve over time. Customers differ in the duration of the trial period and marketing has a different impact on channel choice in the trial and post-trial stages. Furthermore, we show that some people switch channel decision processes while others don’t and we found that several factors have an impact on the probability to switch decision process. Insights from this study can help managers tailor their marketing communication strategy as customers gain channel choice experience. Managers may also have insights on the timing of the direct marketing communications. They can predict the duration of the trial phase at individual level detecting the customers with a quick, long or even absent trial phase. They can even predict if the customer will change or not his decision process over time, and they can influence the switching process using specific marketing tools

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Das Element Arsen besitzt eine Reihe von Isotopen, die in nahezu trägerfreier Form (nca) produziert werden können und deshalb in der Radiopharmazie für die Diagnose oder Endoradiotherapie Verwendung finden können. Bei der Positronenemissionstomographie (PET) gibt es eine gewisse Lücke bei der Versorgung mit langlebigen Positronenemittern, die zur Untersuchung von langsamen physiologischen Prozessen wie z.B. der Biodistribution und Anreicherung von Antikörpern in Tumorgewebe eingesetzt werden können. Die beiden Arsenisotope 72As (T1/2 = 26 h, 88 % beta+) und 74As (T1/2 = 17,8 d, 29 % beta+) vereinen eine lange physikalische Halbwertszeit mit einer hohen Positronenemissionsrate und sind daher geeignete Kandidaten. Da das Verhalten von radioaktivem Arsen und seine Verwendung in der molekularen Bildgebung international relativ wenig bearbeitet sind, wurde die Radiochemie des Arsens von der Isotopenproduktion an Kernreaktor und Zyklotron, über die Entwicklung von Abtrennungsmethoden für Germanium und Arsen, bis hin zur Entwicklung einer soliden Markierungschemie für Antikörper weiterentwickelt. Die in dieser Arbeit bearbeiteten Felder sind: 1. Die Isotopenproduktion der relevanten Arsenisotope (72/74/77As) wurde an Kernreaktor und Zyklotron durch Bestrahlung von GeO2- und Germaniummetalltargets durchgeführt. Pro 6 h Bestrahlung von 100 mg Germanium konnten ca. 2 MBq 77As am TRIGA Reaktor in Mainz hergestellt werden. Am Zyklotron des DKFZ in Heidelberg konnten unter optimierten Bedingungen bei der Bestrahlung von Germaniummetall (EP = 15 Mev, 20 µA, 200 µAh) ca. 4 GBq 72As und ca. 400 MBq 74As produziert werden. 2. Die Entwicklung neuer Abtrennungsmethoden für nca 72/74/77As von makroskopischen Mengen Germanium wurde vorangetrieben. Für die Aufarbeitung von GeO2- und Germaniummetalltargets kamen insgesamt 8 verschiedene Methoden wie Festphasenextraktion, Flüssig-Flüssig-Extraktion, Destillation, Anionenaustauschchromatographie zum Einsatz. Die erzielten Ausbeuten lagen dabei zwischen 31 und 56 %. Es wurden Abtrennungsfaktoren des Germaniums zwischen 1000 und 1•10E6 erreicht. Alle erfolgreichen Abtrennungsmethoden lieferten *As(III) in 500 µl PBS-Puffer bei pH 7. Diese Form des Radioarsens ist für die Markierung von SH-modifizierten Molekülen, wie z.B. Antikörpern geeignet. 3. Die Entwicklung von Methoden zur Bestimmung des Oxidationszustandes von nca *As in organischem, neutralem wässrigen, oder stark sauren Medium mittels Radio-DC und Anionenaustauschchromatographie wurde durchgeführt und führte zu einem besseren Verständnis der Redoxchemie des nca *As. 4. SH-modifizierte Antikörper wurden mit 72/74/77As(III) markiert. Dabei wurden zwei Methoden (Modifizierung mit SATA und TCEP) miteinander verglichen. Während das *As(III) bei Verwendung von TCEP in Ausbeuten > 90 % mit dem Antikörper reagierte, wurde für SATA-modifizierte Antikörper in Abhängigkeit von der verwendeten Abtrennungsmethode eine breite Spanne von 0 % bis > 90 % beobachtet. 5. Es wurden Phantommessungen mit 18F, 72As und 74As am µ-PET-Scanner durchgeführt, um erste Aussagen über die zu erwartende Auflösung der Arsenisotope zu erhalten. Die Auflösung von 74As ist mit 18F vergleichbar, während die von 72As erkennbar schlechter ist.

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In patients with HIV-1 infection who are starting combination antiretroviral therapy (ART), the incidence of immune reconstitution inflammatory syndrome (IRIS) is not well defined. We did a meta-analysis to establish the incidence and lethality of the syndrome in patients with a range of previously diagnosed opportunistic infections, and examined the relation between occurrence and the degree of immunodeficiency. Systematic review identified 54 cohort studies of 13 103 patients starting ART, of whom 1699 developed IRIS. We calculated pooled cumulative incidences with 95% credibility intervals (CrI) by Bayesian methods and did a random-effects metaregression to analyse the relation between CD4 cell count and incidence of IRIS. In patients with previously diagnosed AIDS-defining illnesses, IRIS developed in 37.7% (95% CrI 26.6-49.4) of those with cytomegalovirus retinitis, 19.5% (6.7-44.8) of those with cryptococcal meningitis, 15.7% (9.7-24.5) of those with tuberculosis, 16.7% (2.3-50.7) of those with progressive multifocal leukoencephalopathy, and 6.4% (1.2-24.7) of those with Kaposi's sarcoma, and 12.2% (6.8-19.6) of those with herpes zoster. 16.1% (11.1-22.9) of unselected patients starting ART developed any type of IRIS. 4.5% (2.1-8.6) of patients with any type of IRIS died, 3.2% (0.7-9.2) of those with tuberculosis-associated IRIS died, and 20.8% (5.0-52.7) of those with cryptococcal meningitis died. Metaregression analyses showed that the risk of IRIS is associated with CD4 cell count at the start of ART, with a high risk in patients with fewer than 50 cells per microL. Occurrence of IRIS might therefore be reduced by initiation of ART before immunodeficiency becomes advanced.

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Whitefish, genus Coregonus, show exceptional levels of phenotypic diversity with sympatric morphs occurring in numerous postglacial lakes in the northern hemisphere. Here, we studied the effects of human-induced eutrophication on sympatric whitefish morphs in the Swiss lake, Lake Thun. In particular, we addressed the questions whether eutrophication (i) induced hybridization between two ecologically divergent summer-spawning morphs through a loss of environmental heterogeneity, and (ii) induced rapid adaptive morphological changes through changes in the food web structure. Genetic analysis based on 11 microsatellite loci of 282 spawners revealed that the pelagic and the benthic morph represent highly distinct gene pools occurring at different relative proportions on all seven known spawning sites. Gill raker counts, a highly heritable trait, showed nearly discrete distributions for the two morphs. Multilocus genotypes characteristic of the pelagic morph had more gill rakers than genotypes characteristic of benthic morph. Using Bayesian methods, we found indications of recent but limited introgressive hybridization. Comparisons with historical gill raker data yielded median evolutionary rates of 0.24 haldanes and median selection intensities of 0.27 for this trait in both morphs for 1948-2004 suggesting rapid evolution through directional selection at this trait. However, phenotypic plasticity as an alternative explanation for this phenotypic change cannot be discarded. We hypothesize that both the temporal shifts in mean gill raker counts and the recent hybridization reflect responses to changes in the trophic state of the lake induced by pollution in the 1960s, which created novel selection pressures with respect to feeding niches and spawning site preferences.

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Background Depressive and anxiety symptoms often co-occur resulting in a debate about common and distinct features of depression and anxiety. Methods An exploratory factor analysis (EFA) and a bifactor modelling approach were used to separate a general distress continuum from more specific sub-domains of depression and anxiety in an adolescent community sample (n = 1159, age 14). The Mood and Feelings Questionnaire and the Revised Children's Manifest Anxiety Scale were used. Results A three-factor confirmatory factor analysis is reported which identified a) mood and social-cognitive symptoms of depression, b) worrying symptoms, and c) somatic and information-processing symptoms as distinct yet closely related constructs. Subsequent bifactor modelling supported a general distress factor which accounted for the communality of the depression and anxiety items. Specific factors for hopelessness-suicidal thoughts and restlessness-fatigue indicated distinct psychopathological constructs which account for unique information over and above the general distress factor. The general distress factor and the hopelessness-suicidal factor were more severe in females but the restlessness-fatigue factor worse in males. Measurement precision of the general distress factor was higher and spanned a wider range of the population than any of the three first-order factors. Conclusions The general distress factor provides the most reliable target for epidemiological analysis but specific factors may help to refine valid phenotype dimensions for aetiological research and assist in prognostic modelling of future psychiatric episodes.

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Biodegradable nanoparticles are at the forefront of drug delivery research as they provide numerous advantages over traditional drug delivery methods. An important factor affecting the ability of nanoparticles to circulate within the blood stream and interact with cells is their morphology. In this study a novel processing method, confined impinging jet mixing, was used to form poly (lactic acid) nanoparticles through a solvent-diffusion process with Pluronic F-127 being used as a stabilizing agent. This study focused on the effects of Reynolds number (flow rate), surfactant presence in mixing, and polymer concentration on the morphology of poly (lactic acid) nanoparticles. In addition to looking at the parameters affecting poly (lactic acid) morphology, this study attempted to improve nanoparticle isolation and purification methods to increase nanoparticle yield and ensure specific morphologies were not being excluded during isolation and purification. The isolation and purification methods used in this study were centrifugation and a stir cell. This study successfully produced particles having pyramidal and cubic morphologies. Despite successful production of these morphologies the yield of non-spherical particles was very low, additionally great variability existed between redundant trails. Surfactant was determined to be very important for the stabilization of nanoparticles in solution but appears to be unnecessary for the formation of nanoparticles. Isolation and purification methods that produce a high yield of surfactant free particles have still not been perfected and additional testing will be necessary for improvement.¿

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Serum-based diagnosis offers the prospect of early lung carcinoma detection and of differentiation between benign and malignant nodules identified by CT. One major challenge toward a future blood-based diagnostic consists in showing that seroreactivity patterns allow for discriminating lung cancer patients not only from normal controls but also from patients with non-tumor lung pathologies. We addressed this question for squamous cell lung cancer, one of the most common lung tumor types. Using a panel of 82 phage-peptide clones, which express potential autoantigens, we performed serological spot assay. We screened 108 sera, including 39 sera from squamous cell lung cancer patients, 29 sera from patients with other non-tumor lung pathologies, and 40 sera from volunteers without known disease. To classify the serum groups, we employed the standard Naïve Bayesian method combined with a subset selection approach. We were able to separate squamous cell lung carcinoma and normal sera with an accuracy of 93%. Low-grade squamous cell lung carcinoma were separated from normal sera with an accuracy of 92.9%. We were able to distinguish squamous cell lung carcinoma from non-tumor lung pathologies with an accuracy of 83%. Three phage-peptide clones with sequence homology to ROCK1, PRKCB1 and KIAA0376 reacted with more than 15% of the cancer sera, but neither with normal nor with non-tumor lung pathology sera. Our study demonstrates that seroreactivity profiles combined with statistical classification methods have great potential for discriminating patients with squamous cell lung carcinoma not only from normal controls but also from patients with non-tumor lung pathologies.

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The cytochrome P450 enzyme catalysis requires two electrons transferred from NADPH-cytochrome P450 reductase (reductase) to P450. Electrostatic charge-pairing has been proposed to be one of the major forces in the interaction between P450 and reductase. In order to obtain further insight into the molecular basis for the protein interaction, I used two methods, chemical modification and specific anti-peptide antibodies, to study the involvement and importance of charged amino acid residues. Acetylation of lysine residues of P450c and P450b by acetic anhydride dramatically inhibited the reductase-supported P450c-dependent ethoxycoumarin hydroxylation activity, but P450 activity supported by cumene hydroperoxide is relatively unchanged. The modification of lysine residues of P450c and P450b did not grossly disturb the protein conformation as revealed by several spectral studies. This differential effect of lysine modification on the P450 activity in the system reconstituted with reductase versus the system supported by cumene hydroperoxide suggested an important role for P450 lysine residues in the interaction with reductase. Using $\rm\sp{14}C$-acetic anhydride, P450 lysine residues were labelled and further identified on P450c and P450b. Those lysine residues are at position 97, 271, 279, and 407 for P450c, and 251, 384, 422, 433, and 473 for P450b. Alignment of those identified lysine residues on P450c and P450b with amino acid residues identified in other studies indicated those residues reside in three major sequence areas. Modification of arginine residues of P450b by phenylglyoxal and 2, 3-butanedione have no significant effect on P450 activity either supported by NADPH and reductase or supported by cumene hydroperoxide. Further studies using $\rm\sp{14}C$-phenylglyoxal reveals that no incorporation of phenylglyoxal into P450b was found. These results demonstrated a predominant role of lysine residues of P450 in the electrostatic interaction with reductase. To understand the protein binding sites on each of P450 and reductase, I generated three anti-peptide antibodies against regions on reductase and five anti-peptide antibodies against five putative reductase binding sites on P450c. These anti-peptide antibodies were affinity purified and characterized on ELISA and by Western blot analysis. Inhibition experiments using these antibodies demonstrated that regions 109-120 and 204-220 of reductase are probably the two major binding sites for P450. The association of reductase with cytochromes P450 and cytochrome c may rely on different mechanisms. The data from experiments using anti-peptide (P450c) antibodies supports the important role of P450c lysine residues 271/279 and 458/460 in the interaction with reductase. ^