401 research outputs found

    Some integrability conditions for almost K\"ahler manifolds

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    Among other results, a compact almost K\"ahler manifold is proved to be K\"ahler if the Ricci tensor is semi-negative and its length coincides with that of the star Ricci tensor or if the Ricci tensor is semi-positive and its first order covariant derivatives are Hermitian. Moreover, it is shown that there are no compact almost K\"ahler manifolds with harmonic Weyl tensor and non-parallel semi-positive Ricci tensor. Stronger results are obtained in dimension 4.Comment: Latex2e, 13 page

    The in-plane electrodynamics of the superconductivity in Bi2Sr2CaCu2O8+d: energy scales and spectral weight distribution

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    The in-plane infrared and visible (3 meV-3 eV) reflectivity of Bi2Sr2CaCu2O8+d (Bi-2212) thin films is measured between 300 K and 10 K for different doping levels with unprecedented accuracy. The optical conductivity is derived through an accurate fitting procedure. We study the transfer of spectral weight from finite energy into the superfluid as the system becomes superconducting. In the over-doped regime, the superfluid develops at the expense of states lying below 60 meV, a conventional energy of the order of a few times the superconducting gap. In the underdoped regime, spectral weight is removed from up to 2 eV, far beyond any conventional scale. The intraband spectral weight change between the normal and superconducting state, if analyzed in terms of a change of kinetic energy is ~1 meV. Compared to the condensation energy, this figure addresses the issue of a kinetic energy driven mechanism.Comment: 13 pages with 9 figures include

    Kvaliteta sjemena u ovaca

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    Reproductive evaluation, the selection of individual breeders, and reproductive biotechnologies are important tools in developing productive and reproductive rates. When choosing a male as a breeding future, determining its general health status and genotypic and phenotypic superiority are necessary. This study evaluated the conventional and functional seminal quality in ovine males. The semen of eleven ovines of different pure races was collected by electroejaculation. The following average values were observed for each conventional parameter: scrotal circumference (CE, 34.3 cm), seminal volume (vol, 1.63 mL), concentration (C, 768.4 x 106/mL), individual motility (MI, 80%), masal motility (MM, 4) and vigor (Vi, 3.7). On the other hand, functional analysis showed plasma membrane integrity (PMI) of 45.7%, mitochondrial membrane potential (MMP) of 38.5%, DNA fragmentation index (DFI) of 17.0%, lipoperoxidation of the membrane (LPO) of 32.7%, and the production of reactive oxygen species (ROS) of 28.56%. Additionally, a high and positive correlation was found for variables concerning seminal quality: Vi and MM, Vi and MI, MMP and MM, MMP and MI, PMI and MMP, as well as ROS and MMP. In contrast, two strongly negative correlations were obtained (C vs. Vol and LPO vs. CE). These are the first estimates of functional seminal quality evaluation of sheep in Colombia. In addition, this study provides a baseline for conventional and functional seminal parameters in the region.Reproduktivna procjena, odabir pojedinačnih rasplodnih mužjaka i reproduktivne biotehnologije važni su alati u unaprjeđenju produktivnih i reproduktivnih stopa. Pri odabiru mužjaka za rasplod, potrebno je određivanje općeg zdravstvenog statusa te genotipske i fenotipske superiornosti. Ovaj rad procjenjuje konvencionalnu i funkcionalnu kvalitetu sjemena u ovnova. Sjeme jedanaest ovnova različitih čistokrvnih pasmina prikupljeno je elektroejakulacijom. Zamijećene su sljedeće prosječne vrijednosti za svaki konvencionalni parametar: opseg skrotuma (CE, 34,3 cm), volumen sjemena (vol, 1,63 mL), koncentracija (C, 768,4 x 106/mL), pojedinačna pokretljivost (MI, 80 %), ukupna pokretljivost (MM, 4) i vitalnost (Vi, 3,7). S druge strane, funkcionalna analiza pokazala je integritet stanične membrane (PMI) od 45,7 %, potencijal mitohondrijske membrane (MMP) od 38,5 %, indeks fragmentacije DNK (DFI) od 17,0%, lipoperoksidaciju membrane (LPO) od 32,7 % i proizvodnju reaktivnih kisikovih spojeva (ROS) od 28,56 %. Uz to je otkrivena i visoka i pozitivna korelacija za varijable o kvaliteti sjemena: Vi i MM, Vi i MI, MMP i MM, MMP i MI, PMI i MMP, kao i ROS i MMP. Suprotno tome, dobivene su dvije vrlo negativne korelacije (C nasuprot Vol i LPO nasuprot CE). To su prve procjene ocjenjivanja funkcionalne kvalitete sjemena ovaca u Kolumbiji. Uz to, ova studija osigurava početnu vrijednost za sve konvencionalne i funkcionalne parametre sjemena u regiji

    CARACTERIZACIÓN DE LA CALIDAD FÍSICA DEL CAFÉ DE LOS MUNICIPIOS CAFETEROS DEL NORTE DE ANTIOQUIA-FASE 1

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    Colombia es considerado uno de los países con mayor biodiversidad a nivel mundial, y por tal motivo tiene un gran potencial para exportar diferentes productos agrícolas, entre los cuales está el café. Como objetivo del presente artículo se tiene caracterizar la calidad física del grano de café de los municipios cafeteros del norte de Antioquia, fase 1, para entrar en el mercado del café tostado y ser competitivos en la producción de café. Por esta razón, se utilizó una metodología tipo descriptiva y cualitativa en la que se tostó los granos de café almendra, se determinó el color de los granos tostados para establecer los grados de tostión, se les determinó el porcentaje de merma y, por último, se hizo un análisis organoléptico al café tostado. En la actualidad, el departamento de Antioquia cuenta con 79.452 caficultores y 122.206 hectáreas de café, según la Federación Nacional de Cafeteros; los municipios más representativos de la subregión norte de Antioquia con respecto al café son Angostura, Ituango, Santa Rosa de Osos (especialmente los corregimientos de San Pablo y San Isidro), Don Matías (especialmente la vereda Bellavista), Campamento, Gómez Plata, Guadalupe, Briceño y Yarumal. Como conclusión, se tiene que en la prueba de granulometría de las muestras de café almendra se identificó que el 60 % del grano de café se encontraba por encima de la malla 15, y los mejores resultados de las curvas de tostión del café almendra sana del municipio de Santa Rosa de Osos se obtuvieron con un tiempo de 480 a 660 segundos, y a una temperatura de 185 a 198 °C

    Phase 3 Trial of 177Lu-Dotatate for Midgut Neuroendocrine Tumors

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    Background Patients with advanced midgut neuroendocrine tumors who have had disease progression during first-line somatostatin analogue therapy have limited therapeutic options. This randomized, controlled trial evaluated the efficacy and safety of lutetium-177 (177Lu)-Dotatate in patients with advanced, progressive, somatostatin-receptor-positive midgut neuroendocrine tumors. Methods We randomly assigned 229 patients who had well-differentiated, metastatic midgut neuroendocrine tumors to receive either 177Lu-Dotatate (116 patients) at a dose of 7.4 GBq every 8 weeks (four intravenous infusions, plus best supportive care including octreotide long-acting repeatable [LAR] administered intramuscularly at a dose of 30 mg) (177Lu-Dotatate group) or octreotide LAR alone (113 patients) administered intramuscularly at a dose of 60 mg every 4 weeks (control group). The primary end point was progression-free survival. Secondary end points included the objective response rate, overall survival, safety, and the side-effect profile. The final analysis of overall survival will be conducted in the future as specified in the protocol; a prespecified interim analysis of overall survival was conducted and is reported here. Results At the data-cutoff date for the primary analysis, the estimated rate of progression-free survival at month 20 was 65.2% (95% confidence interval [CI], 50.0 to 76.8) in the 177Lu-Dotatate group and 10.8% (95% CI, 3.5 to 23.0) in the control group. The response rate was 18% in the 177Lu-Dotatate group versus 3% in the control group (P<0.001). In the planned interim analysis of overall survival, 14 deaths occurred in the 177Lu-Dotatate group and 26 in the control group (P=0.004). Grade 3 or 4 neutropenia, thrombocytopenia, and lymphopenia occurred in 1%, 2%, and 9%, respectively, of patients in the 177Lu-Dotatate group as compared with no patients in the control group, with no evidence of renal toxic effects during the observed time frame. Conclusions Treatment with 177Lu-Dotatate resulted in markedly longer progression-free survival and a significantly higher response rate than high-dose octreotide LAR among patients with advanced midgut neuroendocrine tumors. Preliminary evidence of an overall survival benefit was seen in an interim analysis; confirmation will be required in the planned final analysis. Clinically significant myelosuppression occurred in less than 10% of patients in the 177Lu-Dotatate group. (Funded by Advanced Accelerator Applications; NETTER-1 ClinicalTrials.gov number, NCT01578239 ; EudraCT number 2011-005049-11

    Evidence of beta amyloid independent small vessel disease in familial Alzheimer\u27s disease

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    \ua9 2022 The Authors. Brain Pathology published by John Wiley &amp; Sons Ltd on behalf of International Society of Neuropathology. We studied small vessel disease (SVD) pathology in Familial Alzheimer\u27s disease (FAD) subjects carrying the presenilin 1 (PSEN1) p.Glu280Ala mutation in comparison to those with sporadic Alzheimer\u27s disease (SAD) as a positive control for Alzheimer\u27s pathology and Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) bearing different NOTCH3 mutations, as positive controls for SVD pathology. Upon magnetic resonance imaging (MRI) in life, some FAD showed mild white matter hyperintensities and no further radiologic evidence of SVD. In post-mortem studies, total SVD pathology in cortical areas and basal ganglia was similar in PSEN1 FAD and CADASIL subjects, except for the feature of arteriosclerosis which was higher in CADASIL subjects than in PSEN1 FAD subjects. Further only a few SAD subjects showed a similar degree of SVD pathology as observed in CADASIL. Furthermore, we found significantly enlarged perivascular spaces in vessels devoid of cerebral amyloid angiopathy in FAD compared with SAD and CADASIL subjects. As expected, there was greater fibrinogen-positive perivascular reactivity in CADASIL but similar reactivity in PSEN1 FAD and SAD groups. Fibrinogen immunoreactivity correlated with onset age in the PSEN1 FAD cases, suggesting increased vascular permeability may contribute to cognitive decline. Additionally, we found reduced perivascular expression of PDGFRβ AQP4 in microvessels with enlarged PVS in PSEN1 FAD cases. We demonstrate that there is Aβ-independent SVD pathology in PSEN1 FAD, that was marginally lower than that in CADASIL subjects although not evident by MRI. These observations suggest presence of covert SVD even in PSEN1, contributing to disease progression. As is the case in SAD, these consequences may be preventable by early recognition and actively controlling vascular disease risk, even in familial forms of dementia

    Associations between plasma neurofilament light, in vivo brain pathology, and cognition in non-demented individuals with autosomal-dominant Alzheimer's disease

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    BACKGROUND: Neurofilament light (NfL) is a promising biomarker of early neurodegeneration in Alzheimer's disease (AD). We examined whether plasma NfL was associated with in vivo amyloid beta and tau, and cognitive performance in non-demented presenilin-1 (PSEN1) E280A mutation carriers. METHODS: Twenty-five mutation carriers and 19 non-carriers (age range: 28 to 49 years) were included in this study. Participants underwent 11C Pittsburgh compound B (PiB)-PET (positron emission tomography), flortaucipir-PET, blood sampling, and cognitive testing. RESULTS: Mutation carriers exhibited higher plasma NfL levels than non-carriers. In carriers, higher NfL levels were related to greater regional tau burden and worse cognition, but not amyloid beta load. When we adjusted for age, a proxy of disease progression, elevated plasma NfL levels were only correlated with worse memory recall. CONCLUSIONS: Findings support an association between plasma NfL, cognition, and tau pathology in non-demented individuals at genetic risk for developing AD dementia. Plasma NfL may be useful for selecting individuals at increased risk and tracking disease progression in AD

    Pooling/bootstrap-based GWAS (pbGWAS) identifies new loci modifying the age of onset in PSEN1 p.Glu280Ala Alzheimer\u27s disease

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    The literature on GWAS (genome-wide association studies) data suggests that very large sample sizes (for example, 50,000 cases and 50,000 controls) may be required to detect significant associations of genomic regions for complex disorders such as Alzheimer\u27s disease (AD). Because of the challenges of obtaining such large cohorts, we describe here a novel sequential strategy that combines pooling of DNA and bootstrapping (pbGWAS) in order to significantly increase the statistical power and exponentially reduce expenses. We applied this method to a very homogeneous sample of patients belonging to a unique and clinically well-characterized multigenerational pedigree with one of the most severe forms of early onset AD, carrying the PSEN1 p.Glu280Ala mutation (often referred to as E280A mutation), which originated as a consequence of a founder effect. In this cohort, we identified novel loci genome-wide significantly associated as modifiers of the age of onset of AD (CD44, rs187116, P=1.29 _ 10?12; NPHP1, rs10173717, P=1.74 _ 10?12; CADPS2, rs3757536, P=1.54 _ 10?10; GREM2, rs12129547, P=1.69 _ 10?13, among others) as well as other loci known to be associated with AD. Regions identified by pbGWAS were confirmed by subsequent individual genotyping. The pbGWAS methodology and the genes it targeted could provide important insights in determining the genetic causes of AD and other complex conditions
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