821 research outputs found

    Mean value theorems for L-functions over prime polynomials for the rational function field

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    Author's manuscript. The published version is available via: DOI: 10.4064/aa161-4-4The first and second moments are established for the family of quadratic Dirichlet L-functions over the rational function field at the central point s=1/2, where the character χ is defined by the Legendre symbol for polynomials over finite fields and runs over all monic irreducible polynomials P of a given odd degree. Asymptotic formulae are derived for fixed finite fields when the degree of P is large. The first moment obtained here is the function field analogue of a result due to Jutila in the number field setting. The approach is based on classical analytical methods and relies on the use of the analogue of the approximate functional equation for these L-functions.National Science Foundation (NSF)Leverhulme TrustAir Force Office of Scientific Research (USAF

    Automatic for the people

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    BACKGROUND: Neural systems must weight and integrate different sensory cues in order to make decisions. However, environmental conditions often change over time, altering the reliability of different cues and therefore the optimal way for combining them. To explore how cue integration develops in dynamic environments, we examined the effects on auditory spatial processing of rearing ferrets with localization cues that were modified via a unilateral earplug, interspersed with brief periods of normal hearing. RESULTS: In contrast with control animals, which rely primarily on timing and intensity differences between their two ears to localize sound sources, the juvenile-plugged ferrets developed the ability to localize sounds accurately by relying more on the unchanged spectral localization cues provided by the single normal ear. This adaptive process was paralleled by changes in neuronal responses in the primary auditory cortex, which became relatively more sensitive to these monaural spatial cues. Our behavioral and physiological data demonstrated, however, that the reweighting of different spatial cues disappeared as soon as normal hearing was experienced, showing for the first time that this type of plasticity can be context specific. CONCLUSIONS: These results show that developmental changes can be selectively expressed in response to specific acoustic conditions. In this way, the auditory system can develop and simultaneously maintain two distinct models of auditory space and switch between these models depending on the prevailing sensory context. This ability is likely to be critical for maintaining accurate perception in dynamic environments and may point toward novel therapeutic strategies for individuals who experience sensory deficits during development

    Placental Pathology in Relation to Uterine Artery Doppler Findings in Pregnancies with Severe Intrauterine Growth Restriction and Abnormal Umbilical Artery Doppler Changes

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    OBJECTIVES: Current guidelines for diagnosis and management of early-onset intrauterine growth restriction (IUGR) rely on umbilical artery Doppler (UAD), without including uterine artery Doppler (UtAD). We hypothesized that IUGR cases with abnormal UAD but normal UtAD has a different spectrum of placental pathology compared with those with abnormal UtAD. STUDY DESIGN: Retrospective review of pregnancies with sonographic evidence of IUGR and abnormal UAD prior to delivery. Cases with ≥ 1 UtAD record(s) after 18(+0) weeks' gestation and placental pathology were included. Cases were stratified according to initial UtAD pulsatility index (PI) values (n = 196): normal (n = 19; PI < 95th centile for gestational age/no notching), intermediate (n = 69; PI ≥ 95th centile/no/unilateral notching) and abnormal (n = 108; PI ≥ 95th centile/bilateral notching). Pregnancy outcomes and placental pathology were compared between groups. RESULTS: Women in the normal group delivered later than those in the abnormal group (30.1 ± 3.5 vs. 28.0 ± 3.5 weeks; mean ± standard deviation; p = 0.03). Their placentas exhibited higher rates of chronic intervillositis (15.8 vs. 0.9%; p = 0.01), chorangiosis (15.8 vs. 0.9%; p < 0.0001), and massive perivillous fibrin deposition (21.1 vs. 7.4%; p = 0.05), but had lower rates of uteroplacental vascular insufficiency (26.3 vs. 79.6%; p < 0.0001). CONCLUSION: Approximately 10% of pregnancies with early-onset IUGR and abnormal UAD exhibited normal UtAD waveforms. They delivered later, and their placentas exhibited unusual placental pathologies

    Chiropractic at the crossroads or are we just going around in circles?

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    Chiropractic in Australia has seen many changes over the past 30 years. Some of these changes have advanced the professional status of chiropractic, improved undergraduate training and paved the way for a research culture. Unfortunately, other changes or lack of changes, have hindered the growth, public utilisation and professional standing of chiropractic in Australia. This article explores what influences have impacted on the credibility, advancement and public utilisation of chiropractic in Australia

    Mapping Exoplanets

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    The varied surfaces and atmospheres of planets make them interesting places to live, explore, and study from afar. Unfortunately, the great distance to exoplanets makes it impossible to resolve their disk with current or near-term technology. It is still possible, however, to deduce spatial inhomogeneities in exoplanets provided that different regions are visible at different times---this can be due to rotation, orbital motion, and occultations by a star, planet, or moon. Astronomers have so far constructed maps of thermal emission and albedo for short period giant planets. These maps constrain atmospheric dynamics and cloud patterns in exotic atmospheres. In the future, exo-cartography could yield surface maps of terrestrial planets, hinting at the geophysical and geochemical processes that shape them.Comment: Updated chapter for Handbook of Exoplanets, eds. Deeg & Belmonte. 17 pages, including 6 figures and 4 pages of reference

    Stage-Specific Inhibition of MHC Class I Presentation by the Epstein-Barr Virus BNLF2a Protein during Virus Lytic Cycle

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    gamma-herpesvirus Epstein-Barr virus (EBV) persists for life in infected individuals despite the presence of a strong immune response. During the lytic cycle of EBV many viral proteins are expressed, potentially allowing virally infected cells to be recognized and eliminated by CD8+ T cells. We have recently identified an immune evasion protein encoded by EBV, BNLF2a, which is expressed in early phase lytic replication and inhibits peptide- and ATP-binding functions of the transporter associated with antigen processing. Ectopic expression of BNLF2a causes decreased surface MHC class I expression and inhibits the presentation of indicator antigens to CD8+ T cells. Here we sought to examine the influence of BNLF2a when expressed naturally during EBV lytic replication. We generated a BNLF2a-deleted recombinant EBV (ΔBNLF2a) and compared the ability of ΔBNLF2a and wild-type EBV-transformed B cell lines to be recognized by CD8+ T cell clones specific for EBV-encoded immediate early, early and late lytic antigens. Epitopes derived from immediate early and early expressed proteins were better recognized when presented by ΔBNLF2a transformed cells compared to wild-type virus transformants. However, recognition of late antigens by CD8+ T cells remained equally poor when presented by both wild-type and ΔBNLF2a cell targets. Analysis of BNLF2a and target protein expression kinetics showed that although BNLF2a is expressed during early phase replication, it is expressed at a time when there is an upregulation of immediate early proteins and initiation of early protein synthesis. Interestingly, BNLF2a protein expression was found to be lost by late lytic cycle yet ΔBNLF2a-transformed cells in late stage replication downregulated surface MHC class I to a similar extent as wild-type EBV-transformed cells. These data show that BNLF2a-mediated expression is stage-specific, affecting presentation of immediate early and early proteins, and that other evasion mechanisms operate later in the lytic cycle

    Results of the randomized phase IIB ARCTIC trial of low dose Rituximab in previously untreated CLL

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    ARCTIC was a multi-center, randomized-controlled, open, phase IIB non-inferiority trial in previously untreated Chronic Lymphocytic Leukemia (CLL). Conventional frontline therapy in fit patients is fludarabine, cyclophosphamide and rituximab (FCR). The trial hypothesized that including mitoxantrone with low-dose rituximab (FCM-miniR) would be non-inferior to FCR. 200 patients were recruited to assess the primary endpoint of complete remission (CR) rates according to IWCLL criteria. Secondary endpoints were progression-free survival (PFS), overall survival (OS), overall response rate, minimal residual disease (MRD) negativity, safety and cost-effectiveness. The trial closed following the pre-planned interim analysis. At final analysis, CR rates were 76% FCR vs 55% FCM-miniR [adjusted odds-ratio: 0.37; 95% CI: 0.19–0.73]. MRD-negativity rates were 54% FCR vs 44% FCM-miniR. More participants experienced Serious Adverse Reactions with FCM-miniR (49%) compared to FCR (41%). There are no significant differences between the treatment groups for PFS and OS. FCM-miniR is not expected to be cost-effective over a lifetime horizon. In summary, FCM-miniR is less well tolerated than FCR with an inferior response and MRD-negativity rate and increased toxicity, and will not be taken forward into a confirmatory trial. The trial demonstrated that oral FCR yields high response rates compared to historical series with intravenous chemotherapy

    Update in the management of chronic lymphocytic leukemia

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    Advances in the treatment of chronic lymphocytic leukemia (CLL) have improved initial overall response (OR) rates, complete response (CR) rates and progression free survival (PFS). Despite these advances, CLL remains incurable with standard therapies. Thus, there remains a need for more effective therapies in both the upfront and relapsed setting, particularly for patients with high-risk cytogenetic abnormalities such as del(11q22) and del(17p13). The 2008 American Society of Hematology (ASH) Annual Meeting featured several presentations which highlighted the ongoing clinical advances in CLL. The benefit of adding rituximab to purine analog therapy in the upfront setting was demonstrated by a large randomized study which showed that the addition of rituximab to fludarabine and cyclophosphamide (FCR) significantly improved OR, CR and PFS. The improvement in PFS directly resulted from an improved ability to eliminate minimal residual disease (MRD) in the peripheral blood, highlighting the importance of MRD eradication. However, a multi-center study suggested that the high CR rates to chemoimmunotherapy regimens such as FCR obtained in academic centers may not be reproducible when the same regimens are given in the community setting. The immunomodulatory drug lenalidomide is active in relapsed high-risk CLL, but two studies of lenalidomide in previously untreated CLL patients failed to achieve a CR and were associated with significant tumor lysis, tumor flare and hematologic toxicity. In the relapsed setting, a combination study of the bifunctional alkylator bendamustine and rituximab (BR) demonstrated a high OR rate in patients with del(11q22) and del(17p13), indicating that further studies to define's bendamustine activity are warranted in high-risk CLL. Similarly, the CDK inhibitor flavopiridol demonstrated significant clinical activity and durable remissions in heavily treated, refractory CLL patients with high-risk cytogenetic features and bulky lymphadenopathy. The monoclonal anti-CD20 antibody ofatumumab appeared to be superior to rituximab in relapsed CLL patients with bulky nodal disease or high-risk cytogenetic features. Ongoing studies of these agents and other novel therapeutic agents in clinical development hold forth the promise that treatment options for CLL patients will continue to expand and improve
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