196 research outputs found
Darwin, the devil, and the management of transmissible cancers
Modern conservation science frequently relies on genetic tools to manage imperiled populations threatened by processes such as habitat fragmentation and infectious diseases. Translocation of individuals to restore genetic diversity (genetic rescue) is increasingly used to manage vulnerable populations, but it can swamp local adaptations and lead to outbreeding depression. Thus, genetic management is context dependent and needs evaluation across multiple generations . Genomic studies can help evaluate the extent to which populations are locally adapted to assess the costs and benefits of translocations. Predicting the longâterm fitness effects of genetic interventions and their evolutionary consequences is a vital step in managing dwindling populations threatened by emerging infectious diseases
Dental and Periodontal Health in Acute Intermittent Porphyria
In the inherited metabolic disorder acute intermittent porphyria (AIP), high sugar intake
prevents porphyric attacks due to the glucose effect and the following high insulin levels that
may lower AIP disease activity. Insulin resistance is a known risk factor for periodontitis and
sugar changes diabetogenic hormones and affects dental health. We hypothesized differences in
homeostasis model assessment (HOMA) scores for insulin resistance in AIP cases vs. controls and in
those with periodontitis. Our aim was to systematically study dental health in AIP as poor dental
health was previously only described in case reports. Further, we aimed to examine if poor dental
health and kidney failure might worsen AIP as chronic inflammation and kidney failure might
increase disease activity. In 47 AIP cases and 47 matched controls, X-rays and physical examination
of clinical attachment loss (CAL), probing pocket depth (PPD), and decayed missing filled teeth
(DMFT) were performed. Dietary intake was evaluated through a diet logbook. Plasma cytokines
and diabetogenic hormones were measured using multiplex technology and urine porphobilinogen
and kidney and liver function by routine methods. An excel spreadsheet from the University of
Oxford was used to estimate HOMA scores; beta cell function, HOMA%B (%B), insulin sensitivity,
HOMA%S (%S), and insulin resistance HOMA-IR (IR), based on glucose and plasma (P) C-peptide.
The Wilcoxon matched-pairs signed rank test, the MannâWhitney U-test, and Spearmanâs nonparametric correlation were used. Insulin (p = 0.007) and C-peptide (p = 0.006) were higher in the AIP
cases with periodontitis versus those without. In AIP patients, the liver fibrosis index 4 correlated
with DMFT (p < 0.001) and CAL â„4 mm (p = 0.006); the estimated glomerular filtration rate correlated
with DMFT (p < 0.001) and CAL â„4 mm (p = 0.02). CAL â„4 mm was correlated with chemokine
ligand 11 and interleukin (IL)-13 (p = 0.04 for both), and PPD >5 mm was correlated with plasminogen
activator inhibitor-1 (p = 0.003) and complement component 3 (p = 0.02). In conclusion, dental health
in AIP cases was correlated with insulin resistance, inflammatory markers, and biomarkers of kidney
and liver function, demonstrating that organ damage in the kidney and liver are associated with
poorer dental health
Blood Pressure and Body Composition During First Year of Antiretroviral Therapy in People With HIV Compared With HIV-Uninfected Community Controls.
BACKGROUND: Body composition changes may explain the rapid increase in blood pressure (BP) in people with HIV (PWH) during the first year of antiretroviral therapy. METHODS: We analyzed data from a cohort of PWH and HIV-uninfected adults from the same communities in Mwanza, Tanzania. Blood pressure (BP, mm Hg) and body composition data were collected at baseline and 12-month follow-up. We used multivariable linear regression to compare BP changes in PWH and HIV-uninfected adults, and the relationship between changes in body composition and changes in BP. RESULTS: BP data were available for 640 PWH and 299 HIV-uninfected adults. Sixty-four percent were women and the mean age was 38 years. In PWH, systolic BP (SBP) increased (114-118) whereas SBP decreased (125-123) in HIV-uninfected participants. Fat mass increased by 1.6 kg on average in PWH and was strongly associated with the change in BP (P < 0.001). The greater increase in SBP in PWH was partly explained by the lower baseline SBP but PWH still experienced a 2.2 (95% CI: 0.3-4.2) greater increase in SBP after adjustment. Weight gain partially mediated the relationship between HIV and SBP increase in PWH; a 1-kg increase in fat mass accounted for 0.8 (95% CI: 0.6-1.1) increase in SBP. CONCLUSIONS: Weight and fat mass increase rapidly in PWH during the first 12 months of antiretroviral therapy and contribute to a rapid increase in SBP. Interventions to prevent excessive increase in fat mass are needed for PWH
Hard x-ray optics: from HEFT to NuSTAR
Focusing optics are now poised to dramatically improve the sensitivity and angular resolution at energies above 10 keV to levels that were previously unachievable by the past generation of background limited collimated and coded-aperture instruments. Active balloon programs (HEFT), possible Explorer-class satellites (NuSTAR - currently under Phase A study), and major X-ray observatories (Con-X HXT) using focusing optics will play a major role in future observations of a wide range of objects including young supernova remnants, active galactic nuclei, and galaxy clusters. These instruments call for low cost, grazing incidence optics coated with depth-graded multilayer films that can be nested to achieve large collecting areas. Our approach to building such instruments is to mount segmented mirror shells with our novel error-compensating, monolithic assembly and alignment (EMAAL) procedure. This process involves constraining the mirror segments to successive layers of graphite rods that are precisely machined to the required conic-approximation Wolter-I geometry. We present results of our continued development of thermally formed glass substrates that have been used to build three HEFT telescopes and are proposed for NuSTAR. We demonstrate how our experience in manufacturing complete HEFT telescopes, as well as our experience developing higher performance prototype optics, will lead to the successful production of telescopes that meet the NuSTAR design goals
Mechanical design of the optical modules intended for IceCube-Gen2
IceCube-Gen2 is an expansion of the IceCube neutrino observatory at the South Pole that aims to increase the sensitivity to high-energy neutrinos by an order of magnitude. To this end, about 10,000 new optical modules will be installed, instrumenting a fiducial volume of about 8 km3. Two newly developed optical module types increase IceCubeâs current sensitivity per module by a factor of three by integrating 16 and 18 newly developed four-inch PMTs in specially designed 12.5-inch diameter pressure vessels. Both designs use conical silicone gel pads to optically couple the PMTs to the pressure vessel to increase photon collection efficiency. The outside portion of gel pads are pre-cast onto each PMT prior to integration, while the interiors are filled and cast after the PMT assemblies are installed in the pressure vessel via a pushing mechanism. This paper presents both the mechanical design, as well as the performance of prototype modules at high pressure (70 MPa) and low temperature (â40âC), characteristic of the environment inside the South Pole ice
The Surface Array of IceCube-Gen2
The science goals of IceCube-Gen2 include multi-messenger astronomy, astroparticle and particle physics. To this end, the observatory will include several detection methods, including a surface array and in-ice optical sensors. The array will have an approximately 8 km2 surface coverage, consisting of elevated scintillator panels and radio antennas to detect air showers in the energy range of several 100 TeV to a few EeV. The observatoryâs design is unique in that the measurements using the surface array can be combined with the observations of â„ 300 GeV muons, produced in the hadronic cascades, using the optical detectors in the ice. This allows for an enhanced ability to study cosmic-ray and hadronic physics as well as to boost the sensitivity for astrophysical neutrinos from the southern sky by reducing the primary background, atmospheric muons. We will present
the baseline design of the surface array and highlight the expected scientific capabilitie
The next generation neutrino telescope: IceCube-Gen2
The IceCube Neutrino Observatory, a cubic-kilometer-scale neutrino detector at the geographic South Pole, has reached a number of milestones in the field of neutrino astrophysics: the discovery of a high-energy astrophysical neutrino flux, the temporal and directional correlation of neutrinos with a flaring blazar, and a steady emission of neutrinos from the direction of an active galaxy of a Seyfert II type and the Milky Way. The next generation neutrino telescope, IceCube-Gen2, currently under development, will consist of three essential components: an array of about 10,000 optical sensors, embedded within approximately 8 cubic kilometers of ice, for detecting neutrinos with energies of TeV and above, with a sensitivity five times greater than that of IceCube; a surface array with scintillation panels and radio antennas targeting air showers; and buried radio antennas distributed over an area of more than 400 square kilometers to significantly enhance the sensitivity of detecting neutrino sources beyond EeV. This contribution describes the design and status of IceCube-Gen2 and discusses the expected sensitivity from the simulations of the optical, surface, and radio components
Sensitivity of IceCube-Gen2 to measure flavor composition of Astrophysical neutrinos
The observation of an astrophysical neutrino flux in IceCube and its detection capability to separate between the different neutrino flavors has led IceCube to constraint the flavor content of this flux. IceCube-Gen2 is the planned extension of the current IceCube detector, which will be about 8 times larger than the current instrumented volume. In this work, we study the sensitivity of IceCube-Gen2 to the astrophysical neutrino flavor composition and investigate its tau neutrino identification capabilities. We apply the IceCube analysis on a simulated IceCube-Gen2 dataset that mimics the High Energy Starting Event (HESE) classification. Reconstructions are performed using sensors that have 3 times higher quantum efficiency and isotropic angular acceptance compared to the current IceCube optical modules. We present the projected sensitivity for 10 years of data on constraining the flavor ratio of the astrophysical neutrino flux at Earth by IceCube-Gen2
Direction reconstruction performance for IceCube-Gen2 Radio
The IceCube-Gen2 facility will extend the energy range of IceCube to ultra-high energies. The key component to detect neutrinos with energies above 10 PeV is a large array of in-ice radio detectors. In previous work, direction reconstruction algorithms using the forward-folding technique have been developed for both shallow (âČ20 m) and deep in-ice detectors, and have also been successfully used to reconstruct cosmic rays with ARIANNA. Here, we focus on the reconstruction algorithm for the deep in-ice detector, which was recently introduced in the context of the Radio Neutrino Observatory in Greenland (RNO-G)
Estimating the coincidence rate between the optical and radio array of IceCube-Gen2
The IceCube-Gen2 Neutrino Observatory is proposed to extend the all-flavour energy range of IceCube beyond PeV energies. It will comprise two key components: I) An enlarged 8km3 in-ice optical Cherenkov array to measure the continuation of the IceCube astrophysical neutrino flux and improve IceCube\u27s point source sensitivity above âŒ100TeV; and II) A very large in-ice radio array with a surface area of about 500km2. Radio waves propagate through ice with a kilometer-long attenuation length, hence a sparse radio array allows us to instrument a huge volume of ice to achieve a sufficient sensitivity to detect neutrinos with energies above tens of PeV.
The different signal topologies for neutrino-induced events measured by the optical and in-ice radio detector - the radio detector is mostly sensitive to the cascades produced in the neutrino interaction, while the optical detector can detect long-ranging muon and tau leptons with high accuracy - yield highly complementary information. When detected in coincidence, these signals will allow us to reconstruct the neutrino energy and arrival direction with high fidelity. Furthermore, if events are detected in coincidence with a sufficient rate, they resemble the unique opportunity to study systematic uncertainties and to cross-calibrate both detector components
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