4,002 research outputs found
Altering crop management practices to promote pollinators
Agricultural intensification, or the increase in crop production per unit of input or land area to meet the needs of a growing population, has resulted in a landscape dominated by large scale monoculture cropping. Pollinators, specifically, are impacted by the lack of diverse floral and habitat resources associated with this type of farming. Agriculture must develop practices that diversify the crop landscape and increase the availability of habitat and flowering resources to support these populations. In this chapter, we summarize the available literature on how the production space, i.e., within a crop production field, orchard, or pasture, can be more effectively managed to sustain pollinator populations. We report on various spatial and temporal approaches within the context of various cropping systems (row crops, specialty crops, perennial orchards, and perennial forage and pasture systems). Collectively, these approaches represent opportunities to re-introduce diversity into the agricultural landscape to benefit pollinators
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Infectious Syphilis in Non-Hispanic Blacks and Hispanics in an Urban STD Clinic
Syphilis is a complex infectious disease caused by Treponema pallidum and acquired through sexual contact or vertical transmission. The natural history of syphilis is divided in primary, secondary, latent and tertiary stages. The syphilis epidemic has evolved over the years. National rates of syphilis infection dropped to the lowest in 2000 and have since increased in certain populations. Men who have sex with men (MSM) account for 60% of new infections and high rates occur in individuals with human immune deficiency virus co-infection. This study describes and compares the demographic characteristics, risk factors, and clinical presentation ofinfectious syphilis cases diagnosed in the Miami-Dade Health Department STD clinic among the two main ethnicities (non-Hispanic Black and Hispanic)
The Parker Instability in 3-D: Corrugations and Superclouds Along the Carina-Sagittarius Arm
Here we present three-dimensional MHD models for the Parker instability in a
thick magnetized disk, including the presence of a spiral arm. The -field is
assumed parallel to the arm, and the model results are applied to the optical
segment of the Carina-Sagittarius arm. The characteristic features of the
undular and interchange modes are clearly apparent in the simulations. The
undular mode creates large gas concentrations distributed along the arm. This
results in a clear arm/inter-arm difference: the instability triggers the
formation of large interstellar clouds inside the arms, but generates only
small structures with slight density enhancements in the inter-arm regions. The
resulting clouds are distributed in an antisymmetric way with respect to the
midplane, creating an azimuthal corrugation along the arm. For conditions
similar to those of the optical segment of the Carina-Sagittarius arm, it has a
wavelength of about 2.4 kpc. This structuring can explain the origin of both HI
superclouds and the azimuthal corrugations in spiral arms. The wavelength
matches the corrugation length derived with the young stellar groups located in
the optical segment of the Carina-Sagittarius arm. Keywords: Galaxy: kinematics
and dynamics -- Galaxy: structure -- Instabilities -- ISM: clouds -- ISM:
magnetic fields -- ISM: structure -- MHDComment: 29 pages, 12 figures, Latex, Accepted by the Astrophysical Journa
Superbubble evolution including the star-forming clouds: Is it possible to reconcile LMC observations with model predictions?
Here we present a possible solution to the apparent discrepancy between the
observed properties of LMC bubbles and the standard, constant density bubble
model. A two-dimensional model of a wind-driven bubble expanding from a
flattened giant molecular cloud is examined. We conclude that the expansion
velocities derived from spherically symmetric models are not always applicable
to elongated young bubbles seen almost face-on due to the LMC orientation. In
addition, an observational test to differentiate between spherical and
elongated bubbles seen face-on is discussed.Comment: 25 pages, 7 figures, accepted to ApJ (September, 1999 issue
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Human Inborn Errors of Immunity: 2019 Update of the IUIS Phenotypical Classification.
Since 2013, the International Union of Immunological Societies (IUIS) expert committee (EC) on Inborn Errors of Immunity (IEI) has published an updated phenotypic classification of IEI, which accompanies and complements their genotypic classification into ten tables. This phenotypic classification is user-friendly and serves as a resource for clinicians at the bedside. There are now 430 single-gene IEI underlying phenotypes as diverse as infection, malignancy, allergy, autoimmunity, and autoinflammation. We herein report the 2019 phenotypic classification, including the 65 new conditions. The diagnostic algorithms are based on clinical and laboratory phenotypes for each of the ten broad categories of IEI
Pregnancy outcomes in women with repeated implantation failures after intracytoplasmic morphologically selected sperm injection (IMSI)
<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to compare laboratory and clinical outcomes of intracytoplasmic morphologically selected sperm injection (IMSI) and conventional intracytoplasmic sperm injection (ICSI) in couples with repeated implantation failures.</p> <p>Methods</p> <p>A total of 200 couples with at least two prior unsuccessful ICSI cycles were enrolled: 100 couples were submitted to IMSI and 100 were submitted to routine ICSI. For IMSI, spermatozoa were selected at 8400× magnification using an inverted microscope equipped with Nomarski (differential interference contrast) optics. For conventional ICSI, spermatozoa were selected at 400× magnification. Clinical outcomes were evaluated between the two groups.</p> <p>Results</p> <p>Study patients were comparable in age, number of treatment failures, aetiology of infertility, percentage of normal form assessed by MSOME (motile sperm organelle morphology examination), semen parameters, total number of oocytes collected, number of mature oocytes collected, total number of embryos transferred and number of high-quality embryos transferred. No statistically significant differences between the two groups were observed with regard to rates of fertilisation, implantation and pregnancy/cycle. Although not statistically significant, rates of miscarriage (IMSI:15.3% vs ICSI:31.7%), ongoing pregnancy (IMSI:22% vs ICSI:13%) and live births (IMSI:21% vs ICSI:12%) showed a trend towards better outcomes in the IMSI group. In addition, analysis of subpopulations with or without male factor showed similar results.</p> <p>Conclusions</p> <p>Our results suggest that IMSI does not provide a significant improvement in clinical outcome compared to ICSI, at least in couples with repeated implantation failures after conventional ICSI. However, it should be noted that there were clear trends for lower miscarriage rates (≈50% reduced) and higher rates of ongoing pregnancy and live births (both nearly doubled) within the IMSI group. Further confirmation as well as randomized large-scale trials are needed to confirm the beneficial effects of IMSI in couples with poor reproductive prognoses.</p
Dynamical supersymmetry breaking from unoriented D-brane instantons
We study the non-perturbative dynamics of an unoriented Z_5-quiver theory of
GUT kind with gauge group U(5) and chiral matter. At strong coupling the
non-perturbative dynamics is described in terms of set of baryon/meson
variables satisfying a quantum deformed constraint. We compute the effective
superpotential of the theory and show that it admits a line of supersymmetric
vacua and a phase where supersymmetry is dynamically broken via gaugino
condensation.Comment: 24 pages, 1 figur
From Ultracompact to Extended HII Regions. II: Cloud Gravity and Stellar Motion
The dynamical evolution of HII regions with and without stellar motion in
dense, structured molecular clouds is studied. Clouds are modeled in
hydrostatic equilibrium, with gaussian central cores and external halos that
obey r**-2 and r**-3 density power laws. The cloud gravity is included as a
time-independent, external force. Stellar velocities of 0, 2, 8, and 12 km/s
are considered. When stellar motion is included, stars move from the central
core to the edge of the cloud, producing transitions from ultracompact to
extended HII regions as the stars move into lower density regions. The opposite
behavior occurs when stars move toward the cloud cores. The main conclusion of
our study is that ultracompact HII regions are pressure-confined entities while
they remain embedded within dense cores. The confinement comes from ram and/or
ambient pressures. The survival of ultracompact regions depends on the position
of the star with respect to the core, the stellar life-time, and the core
crossing time. Stars with velocities less than the cloud dispersion velocity
can produce cometary shapes smaller than 0.1 pc at times of 20,000 yr or more.
The sequence Ultracompact to Compact to Extended HII region shows a variety of
unpredictable structures due to ionization-shock front instability. Some
ultracompact HII regions with a core-halo morphology might be explained by
self-blocking effects, when stars overtake and ionize leading, piled-up clumps
of neutral gas. We use thermal energy to support the cloud against gravity; the
results remain the same if other types of isotropic cloud support are used.Comment: 27 pages, 7 ps figures, 5 png figures; submitted to Astrophysical
Journa
The Human African Trypanosomiasis Specimen Biobank: A Necessary Tool to Support Research of New Diagnostics
Subtelomeric I-Scel-Mediated Double-Strand Breaks Are Repaired by Homologous Recombination in Trypanosoma cruzi
Trypanosoma cruzi chromosome ends are enriched in surface protein genes and pseudogenes (e.g., trans-sialidases) surrounded by repetitive sequences. It has been proposed that the extensive sequence variability among members of these protein families could play a role in parasite infectivity and evasion of host immune response. In previous reports we showed evidence suggesting that sequences located in these regions are subjected to recombination. To support this hypothesis we introduced a double-strand break (DSB) at a specific target site in a I cruzi subtelomeric region cloned into an artificial chromosome (pTAC). This construct was used to transfect T. cruzi epimastigotes expressing the I-Scel meganuclease. Examination of the repaired sequences showed that DNA repair occurred only through homologous recombination (HR) with endogenous subtelomeric sequences. Our findings suggest that DSBs in subtelomeric repetitive sequences followed by HR between them may contribute to increased variability in T. cruzi multigene families.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ Centroccidental Lisandro Alvarado, Lab Genet Mol Dr Yunis Turbay, Ciencias Salud, Barquisimeto, VenezuelaNIAID, Lab Malaria & Vector Res, NIH, Rockville, MD USAUniv Fed Sao Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, Sao Paulo, BrazilConsejo Nacl Invest Cient & Tecn, Inst Invest Ingn Genet & Biol Mol, Lab Biol Mol Enfermedad Chagas, Buenos Aires, DF, ArgentinaJ Craig Venter Inst, Dept Infect Dis, Rockville, MD USAFdn Inst Estudios Avanzados, Ctr Biotecnol, Caracas, VenezuelaUniv Estadual Campinas, Fac Ciencias Med, Dept Patol Clin, Campinas, SP, BrazilDepartamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, BrazilFAPESP: 11/51693-0FAPESP: 11/51475-3CNPq: 306591/2015-4Web of Scienc
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