Two-divisibility of the coefficients of certain weakly holomorphic modular forms

We study a canonical basis for spaces of weakly holomorphic modular forms of weights 12, 16, 18, 20, 22, and 26 on the full modular group. We prove a relation between the Fourier coefficients of modular forms in this canonical basis and a generalized Ramanujan tau-function, and use this to prove that these Fourier coefficients are often highly divisible by 2.Comment: Corrected typos. To appear in the Ramanujan Journa

Phylogenetic diversity and temporal variation in the Spirochaeta populations from two Mediterranean microbial mats

Spirochetes represent one of the bacterial groups often observed in hydrogen- sulfide-rich layers from coastal microbial mats. However, relatively few spirochetes from these microbial mats have been described and characterized. We have used 16S rDNA phylogenetic analysis to investigate the spirochetal diversity of microbial mats from two different geographic locations in the western Mediterranean (Ebro Delta, Spain, and Camargue, France). Samples from each delta was monitored in the spring and winter over 1 to 2 year’s duration. In the sequence analysis of 332 clones derived from samples of both deltas, 42 novel phylotypes of not-yet-cultivated spirochetes belonging to the genus Spirochaeta were detected. None of the phylotypes were identified as known culturable species of Spirochaeta or previously identified phylotyepes cloned from other hypersaline microbial mat such as Guerrero Negro. Eight of the phylotypes were common to Ebro and Camargue mats, two of them, IF058 and LL066 are present both in spring and winter. Some phylotypes appeared to show seasonal variation, i.e. they were found only in the spring, but not in the winter. On the other hand, Ebro and Camargue phylotypes compared with phylotypes from Guerrero Negro grouped according to the vertical gradient of oxygen and sulfide in the mat. Some phylotypes, such as LH073, IE028, LH042 or LG013 are harbored in low H2S or H2S-O2 interface zone. In contrast, major phylotypes were detected presumably in deeper layers and they are likely to be strict anaerobes and high tolerance to H2S. The presence of spirochetes in different located microbial mats suggests that constitutes a very diverse and stable population involved in a well-integrated “symbiosis” (i.e., permanent physiological cooperation) with other guild-populations in the mats to maintain a coordinated functional and stable community

Experimental Determination of the Effective Nucleon-Nucleon Interaction for P-Nucleus Reactions at Intermediate Energies

A complete measurement of the polarization transfer observables has been made for the first time in the (p,p') reaction at intermediate energies. Measurements are reported for the /sup 12/C(p,p') /sup 12/C reaction to the 1/sup +/, T = 0(12.71 MeV) and 1/sup +/, T = 1(15.11 MeV) states at 500 MeV at laboratory scattering angles of 3.5/sup 0/, 5.5/sup 0/, 7.5/sup 0/, and 12.0/sup 0/. Linear combinations of these observables are shown to exhibit a very selective dependence on the isoscalar and isovector spin-dependent components of the nucleon-nucleon interaction. To the extent of the validity of the single collision approximation, these amplitudes are compared directly to the free nucleon-nucleon amplitudes at small momentum transfers ( < 1 fm/sup -1/)

Nitrate dry deposition in Svalbard

This is the final version of the article. Available from Taylor & Francis via the DOI in this record.Arctic regions are generally nutrient limited, receiving an extensive part of their bio-available nitrogen from the deposition of atmospheric reactive nitrogen. Reactive nitrogen oxides, as nitric acid (HNO3) and nitrate aerosols (p-NO3), can either be washed out from the atmosphere by precipitation or dry deposited, dissolving to nitrate (). During winter, is accumulated in the snowpack and released as a pulse during spring melt. Quantification of deposition is essential to assess impacts on Arctic terrestrial ecology and for ice core interpretations. However, the individual importance of wet and dry deposition is poorly quantified in the high Arctic regions where in-situ measurements are demanding. In this study, three different methods are employed to quantify dry deposition around the atmospheric and ecosystem monitoring site, Ny-Ålesund, Svalbard, for the winter season (September 2009 to May 2010): (1) A snow tray sampling approach indicates a dry deposition of –10.27±3.84 mg m−2 (± S.E.); (2) A glacial sampling approach yielded somewhat higher values –30.68±12.00 mg m−2; and (3) Dry deposition was also modelled for HNO3 and p-NO3 using atmospheric concentrations and stability observations, resulting in a total combined nitrate dry deposition of –10.76±1.26 mg m−2. The model indicates that deposition primarily occurs via HNO3 with only a minor contribution by p-NO3. Modelled median deposition velocities largely explain this difference: 0.63 cm s−1 for HNO3 while p-NO3 was 0.0025 and 0.16 cm s−1 for particle sizes 0.7 and 7 µm, respectively. Overall, the three methods are within two standard errors agreement, attributing an average 14% (total range of 2–44%) of the total nitrate deposition to dry deposition. Dry deposition events were identified in association with elevated atmospheric concentrations, corroborating recent studies that identified episodes of rapid pollution transport and deposition to the Arctic.As a part of the international project ‘Sources, sinks and impacts of atmospheric nitrogen deposition in the Arctic’ (NSINK), this project received financial support from an EU Marie Curie Initial Stage Training Network Award NSINK (FP7 215503) and fieldwork were supported by an Arctic Field Grant, Svalbard Science Forum. NILU's atmospheric monitoring program at the Zeppelin Station is financed by the Norwegian Climate and Pollution Agency and ITM's research at the same station is supported by the Swedish Environmental Protection Agency. This is also a contribution to ‘Crysophere-Atmosphere interaction in a changing Arctic climate (CRAICC)’ a Top-Level Research Initiative (TRI). Logistic support was provided by the Norwegian Polar Institute staff at the Sverdrup Station, Ny-Ålesund, while A. Nowak-Zwierz, K. A. Kozio and C. L. Chakrabarti contributed to the analytical work in Sheffield, and J. Kohler kindly provided snow accumulation data from Austre Brøggerbreen

Factor copula models for item response data

Factor or conditional independence models based on copulas are proposed for multivariate discrete data such as item responses. The factor copula models have interpretations of latent maxima/minima (in comparison with latent means) and can lead to more probability in the joint upper or lower tail compared with factor models based on the discretized multivariate normal distribution (or multidimensional normal ogive model). Details on maximum likelihood estimation of parameters for the factor copula model are given, as well as analysis of the behavior of the log-likelihood. Our general methodology is illustrated with several item response data sets, and it is shown that there is a substantial improvement on existing models both conceptually and in fit to data

Hybrid copula mixed models for combining case-control and cohort studies in meta-analysis of diagnostic tests

Copula mixed models for trivariate (or bivariate) meta-analysis of diagnostic test accuracy studies accounting (or not) for disease prevalence have been proposed in the biostatistics literature to synthesize information. However, many systematic reviews often include case-control and cohort studies, so one can either focus on the bivariate meta-analysis of the case-control studies or the trivariate meta-analysis of the cohort studies, as only the latter contains information on disease prevalence. In order to remedy this situation of wasting data we propose a hybrid copula mixed model via a combination of the bivariate and trivariate copula mixed model for the data from the case-control studies and cohort studies, respectively. Hence, this hybrid model can account for study design and also due to its generality can deal with dependence in the joint tails. We apply the proposed hybrid copula mixed model to a review of the performance of contemporary diagnostic imaging modalities for detecting metastases in patients with melanoma

Standardization of Preclinical PET/CT Imaging to Improve Quantitative Accuracy, Precision, and Reproducibility: A Multicenter Study

Preclinical PET/CT is a well-established noninvasive imaging tool for studying disease development/progression and the development of novel radiotracers and pharmaceuticals for clinical applications. Despite this pivotal role, standardization of preclinical PET/CT protocols, including CT absorbed dose guidelines, is essentially nonexistent. This study (1) quantitatively assesses the variability of current preclinical PET/CT acquisition and reconstruction protocols routinely used across multiple centers and scanners; and (2) proposes acquisition and reconstruction PET/CT protocols for standardization of multicenter data, optimized for routine scanning in the preclinical PET/CT laboratory. Methods: Five different commercial preclinical PET/CT scanners in Europe and the United States were enrolled. Seven different PET/CT phantoms were used for evaluating biases on default/general scanner protocols, followed by developing standardized protocols. PET, CT, and absorbed dose biases were assessed. Results: Site default CT protocols were the following: greatest extracted Hounsfield units (HU) were 133 HU for water and −967 HU for air; significant differences in all tissue equivalent material (TEM) groups were measured. The average CT absorbed doses for mouse and rat were 72 mGy and 40 mGy, respectively. Standardized CT protocol were the following: greatest extracted HU were −77 HU for water and −990 HU for air; TEM precision improved with a reduction in variability for each tissue group. The average CT absorbed dose for mouse and rat decreased to 37 mGy and 24 mGy, respectively. Site default PET protocols were the following: uniformity was substandard in one scanner, recovery coefficients (RCs) were either over- or underestimated (maximum of 43%), standard uptake values (SUVs) were biased by a maximum of 44%. Standardized PET protocols were the following: scanner with substandard uniformity improved by 36%, RC variability decreased by 13% points, and SUV accuracy improved to 10%. Conclusion: Data revealed important quantitative biases in preclinical PET/CT and absorbed doses with default protocols. Standardized protocols showed improvements in measured PET/CT accuracy and precision with reduced CT absorbed dose across sites. Adhering to standardized protocols generates reproducible and consistent preclinical imaging datasets, thus augmenting translation of research findings to the clinic

Transcription profiling reveals potential mechanisms of dysbiosis in the oral microbiome of rhesus macaques with chronic untreated SIV infection.

A majority of individuals infected with human immunodeficiency virus (HIV) have inadequate access to antiretroviral therapy and ultimately develop debilitating oral infections that often correlate with disease progression. Due to the impracticalities of conducting host-microbe systems-based studies in HIV infected patients, we have evaluated the potential of simian immunodeficiency virus (SIV) infected rhesus macaques to serve as a non-human primate model for oral manifestations of HIV disease. We present the first description of the rhesus macaque oral microbiota and show that a mixture of human commensal bacteria and "macaque versions" of human commensals colonize the tongue dorsum and dental plaque. Our findings indicate that SIV infection results in chronic activation of antiviral and inflammatory responses in the tongue mucosa that may collectively lead to repression of epithelial development and impact the microbiome. In addition, we show that dysbiosis of the lingual microbiome in SIV infection is characterized by outgrowth of Gemella morbillorum that may result from impaired macrophage function. Finally, we provide evidence that the increased capacity of opportunistic pathogens (e.g. E. coli) to colonize the microbiome is associated with reduced production of antimicrobial peptides

The Discovery of Two New Satellites of Pluto

Pluto's first known moon, Charon, was discovered in 1978 (Christy 1978) and has a diameter about half that of Pluto (Buie 1992,Young 1994, Sicardy 2005), which makes it larger relative to its primary than any other moon in the Solar System. Previous searches for other satellites around Pluto have been unsuccessful (Stern 1991, Stern 1994, Stern 2003), but they were not sensitive to objects <=150 km in diameter and there are no fundamental reasons why Pluto should not have more satellites (Stern 1994). Here we report the discovery of two additional moons around Pluto, provisionally designated S/2005 P1 (hereafter P1) and S/2005 P2 (hereafter P2), which makes Pluto the first Kuiper belt object (KBO) known to have multiple satellites. These new satellites are much smaller than Charon (diameter~1200 km), with P1 ranging in diameter from 60-165 km depending on the surface reflectivity, and P2 about 20% smaller than P1. Although definitive orbits cannot be derived, both new satellites appear to be moving in circular orbits in the same orbital plane as Charon, with orbital periods of ~38 days (P1) and ~25 days (P2). The implications of the discovery of P1 and P2 for the origin and evolution of the Pluto system, and for the satellite formation process in the Kuiper belt, are discussed in a companion paper (Stern 2006).Comment: Preprint of a paper accepted for publication in the journal Natur