1,210 research outputs found
Response of CO<sub>2</sub> and CH<sub>4</sub> emissions from Arctic tundra soils to a multifactorial manipulation of water table, temperature and thaw depth
Significant uncertainties persist concerning how Arctic soil tundra carbon emission responds to
environmental changes. In this study, 24 cores were sampled from drier (high centre polygons and
rims) and wetter (low centre polygons and troughs) permafrost tundra ecosystems. We examined
how soil CO2 and CH4 fluxes responded to laboratory-based manipulations of soil temperature
(and associated thaw depth) and water table depth, representing current and projected conditions
in the Arctic. Similar soil CO2 respiration rates occurred in both the drier and the wetter sites,
suggesting that a significant proportion of soil CO2 emission occurs via anaerobic respiration
under water-saturated conditions in these Arctic tundra ecosystems. In the absence of vegetation,
soil CO2 respiration rates decreased sharply within the first 7 weeks of the experiment, while CH4
emissions remained stable for the entire 26 weeks of the experiment. These patterns suggest that
soil CO2 emission is more related to plant input than CH4 production and emission. The stable
and substantial CH4 emission observed over the entire course of the experiment suggests that
temperature limitations, rather than labile carbon limitations, play a predominant role in CH4
production in deeper soil layers. This is likely due to the presence of a substantial source of labile
carbon in these carbon-rich soils. The small soil temperature difference (a median difference of
1
âŠC) and a more substantial thaw depth difference (a median difference of 6 cm) between the high
and low temperature treatments resulted in a non-significant difference between soil CO2 and CH4
emissions. Although hydrology continued to be the primary factor influencing CH4 emissions,
these emissions remained low in the drier ecosystem, even with a water table at the surface. This
result suggests the potential absence of a methanogenic microbial community in high-centre
polygon and rim ecosystems. Overall, our results suggest that the temperature increases reported
for these Arctic regions are not responsible for increases in carbon losses. Instead, it is the changes
in hydrology that exert significant control over soil CO2 and CH4 emissions
Quantifying sympathetic neuro-haemodynamic transduction at rest in humans:Insights into sex, ageing and blood pressure control
KEY POINTS: We have developed a simple analytical method for quantifying the transduction of sympathetic activity into vascular tone. This method demonstrates that as women age, the transfer of sympathetic nerve activity into vascular tone is increased, so that for a given level of sympathetic activity there is more vasoconstriction. In men, this measure decreases with age. Testâreâtest analysis demonstrated that the new method is a reliable estimate of sympathetic transduction. We conclude that increased sympathetic vascular coupling contributes to the ageârelated increase in blood pressure that occurs in women only. This measure is a reliable estimate of sympathetic transduction in populations with high sympathetic nerve activity. Thus, it will provide information regarding whether treatment targeting the sympathetic nervous system, which interrupts the transfer of sympathetic nerve activity into vascular tone, will be effective in reducing blood pressure in hypertensive patients. This may provide insight into which populations will respond to certain types of antiâhypertensive medication. ABSTRACT: Sex and age differences in the sympathetic control of resting blood pressure (BP) may be due to differences in the transduction of sympathetic nerve activity (SNA) into vascular tone. Current methods for dynamically quantifying transduction focus on the relationship between SNA and vasoconstriction during a pressor stimulus, which increases BP and may be contraâindicated in patients. We describe a simple analytical method for quantifying transduction under resting conditions. We performed linear regression analysis of binned muscle SNA burst areas against diastolic BP (DBP). We assessed whether the slope of this relationship reflects the transduction of SNA into DBP. To evaluate this, we investigated whether this measure captures differences in transduction in different populations. Specifically, we (1) quantified transduction in young men (YM), young women (YW), older men (OM) and postmenopausal women (PMW); and (2) measured changes in transduction during ÎČâblockade using propranolol in YW, YM and PMW. YM had a greater transduction vs. OM (0.10 ± 0.01 mmHg (% s)(â1), n = 23 vs. 0.06 ± 0.01 mmHg (% s)(â1), n = 18; P = 0.003). Transduction was lowest in YW (0.02 ± 0.01 mmHg (% s)(â1), n = 23) and increased during ÎČâblockade (0.11 ± 0.01 mmHg (% s)(â1); P < 0.001). Transduction in PMW (0.07 ± 0.01 mmHg (% s)(â1), n = 23) was greater compared to YW (P = 0.001), and was not altered during ÎČâblockade (0.06 ± 0.01 mmHg (% s)(â1); P = 0.98). Importantly, transduction increased in women with age, but decreased in men. Transduction in women intersected that in men at 55 ± 1.5 years. This measure of transduction captures ageâ and sexâdifferences in the sympathetic regulation of DBP and may be valuable in quantifying transduction in disease. In particular, this measure may help target treatment strategies in specific hypertensive subpopulations
Experimental and theoretical study of resonant core-hole spectroscopies of gas-phase free-base phthalocyanine
We studied N 1sâ1 inner-shell processes of the free base Phthalocyanine molecule, H2Pc, in the gas-phase. This complex organic molecule contains three different nitrogen sites defined by their covalent bonds. We identify the contribution of each site in ionized, coreâshell excited or relaxed electronic states by the use of different theoretical methods. In particular, we present resonant Auger spectra along with a tentative new theoretical approach based on multiconfiguration self-consistent field calculations to simulate them. These calculations may pave the road towards resonant Auger spectroscopy in complex molecules
Grado de conocimiento sobre su enfermedad en pacientes diabĂ©ticos que se controlan en el servicio de EndocrinologĂa del Hospital âJosĂ© F. de San Martinâ. Año 2016
LLa Diabetes Mellitus es una enfermedad crĂłnica las complicaciones asociadas a la misma se vinculan con el grado de conocimiento que tenga elpaciente sobre su enfermedad. Se realizĂł un estudio cuantitativo, transversal y descriptivo con el objetivo de estimar el grado de conocimiento sobre Diabetes relacionĂĄndola con edad, sexo, nivel de instrucciĂłn, situaciĂłn laboral, estado civil, situaciĂłnde convivencia, presencia o no de antecedentes de Diabetes de tipo II en familiares directos y tipo de tratamiento que recibĂan. La poblaciĂłn en estudio fue una muestra de 90 pacientes controlados en el servicio de EndocrinologĂa del Hospital âJosĂ© F. de San Martinâ, durante el año 2016. Se analizĂł el grado de conocimiento mediante un instrumento basado en un cuestionario realizado por la Universidad de Michigan (EUA) y un cuestionario de Diabetes ECODI (Escala de conocimientos de Diabetes). Las operaciones estadĂsticas utilizadas fueron porcentajes y promedios en el programa âExcelâ.RESULTADOSEl 69% de los pacientes encuestados obtuvo un grado de conocimiento aceptable; de estos la mayorĂa no tenĂan antecedentes de Diabetes, eran adultos maduros (36 a 59años de edad), pertenecĂan al sexo femenino, tenĂan riesgo educativo (personas con escolaridad bĂĄsica incompleta), trabajaban de forma independiente, eran solteros, vivĂan solos y tenĂan la alimentaciĂłn como principal tratamiento.DISCUSIĂNExisten estudios antecedentes que demuestran que el grado de conocimientos de pacientes diabĂ©ticos sobre su enfermedad influye directamente en el autocuidado de los mismos. Este estudio evidenciĂł que el grado de conocimiento sobre su enfermedad es aceptable en los sujetos estudiados resultados similares a lo obtenido por RodrĂguez en Buenos Aires Argentina 2015.CONCLUSIONESSe encontrĂł un nivel de conocimientos aceptable, se sugiere implementar talleres supervisados para evaluar autocuidado, estrategias demostrativas sobre complicaciones para concientizar y lograr mantener un buen nivel de conocimientos o mejorarlo
Free-space cavity optomechanics in a cryogenic environment
International audienceWe present a free-space optomechanical system operating in the 1-K range. The device is made ofa high mechanical quality factor micropillar with a high-reflectivity optical coating atop, combinedwith an ultra-small radius-of-curvature coupling mirror to form a high-finesse Fabry-Perot cavityembedded in a dilution refrigerator. The cavity environment as well as the cryostat have beendesigned to ensure low vibrations and to preserve micron-level alignment from room temperatur
Response of CO2 and CH4 emissions from Arctic tundra soils to a multifactorial manipulation of water table, temperature and thaw depth
Significant uncertainties persist concerning how Arctic soil tundra carbon emission responds to environmental changes. In this study, 24 cores were sampled from drier (high centre polygons and rims) and wetter (low centre polygons and troughs) permafrost tundra ecosystems. We examined how soil CO2 and CH4 fluxes responded to laboratory-based manipulations of soil temperature (and associated thaw depth) and water table depth, representing current and projected conditions in the Arctic. Similar soil CO2 respiration rates occurred in both the drier and the wetter sites, suggesting that a significant proportion of soil CO2 emission occurs via anaerobic respiration under water-saturated conditions in these Arctic tundra ecosystems. In the absence of vegetation, soil CO2 respiration rates decreased sharply within the first 7 weeks of the experiment, while CH4 emissions remained stable for the entire 26 weeks of the experiment. These patterns suggest that soil CO2 emission is more related to plant input than CH4 production and emission. The stable and substantial CH4 emission observed over the entire course of the experiment suggests that temperature limitations, rather than labile carbon limitations, play a predominant role in CH4 production in deeper soil layers. This is likely due to the presence of a substantial source of labile carbon in these carbon-rich soils. The small soil temperature difference (a median difference of 1 °C) and a more substantial thaw depth difference (a median difference of 6 cm) between the high and low temperature treatments resulted in a non-significant difference between soil CO2 and CH4 emissions. Although hydrology continued to be the primary factor influencing CH4 emissions, these emissions remained low in the drier ecosystem, even with a water table at the surface. This result suggests the potential absence of a methanogenic microbial community in high-centre polygon and rim ecosystems. Overall, our results suggest that the temperature increases reported for these Arctic regions are not responsible for increases in carbon losses. Instead, it is the changes in hydrology that exert significant control over soil CO2 and CH4 emissions
High-sensitivity AC-charge detection with a MHz-frequency fluxonium qubit
Owing to their strong dipole moment and long coherence times, superconducting
qubits have demonstrated remarkable success in hybrid quantum circuits.
However, most qubit architectures are limited to the GHz frequency range,
severely constraining the class of systems they can interact with. The
fluxonium qubit, on the other hand, can be biased to very low frequency while
being manipulated and read out with standard microwave techniques. Here, we
design and operate a heavy fluxonium with an unprecedentedly low transition
frequency of . We demonstrate resolved sideband cooling of
the ``hot'' qubit transition with a final ground state population of ,
corresponding to an effective temperature of . We further
demonstrate coherent manipulation with coherence times ,
, and single-shot readout of the qubit state.
Importantly, by directly addressing the qubit transition with a capacitively
coupled waveguide, we showcase its high sensitivity to a radio-frequency field.
Through cyclic qubit preparation and interrogation, we transform this
low-frequency fluxonium qubit into a frequency-resolved charge sensor. This
method results in a charge sensitivity of
, or an energy sensitivity (in joules per
hertz) of . This method rivals state-of-the-art transport-based
devices, while maintaining inherent insensitivity to DC charge noise. The high
charge sensitivity combined with large capacitive shunt unlocks new avenues for
exploring quantum phenomena in the range, such as the
strong-coupling regime with a resonant macroscopic mechanical resonator
Unilateral Carotid Body Resection in Resistant Hypertension:A Safety and Feasibility Trial
SummaryAnimal and human data indicate pathological afferent signaling emanating from the carotid body that drives sympathetically mediated elevations in blood pressure in conditions of hypertension. This first-in-man, proof-of-principle study tested the safety and feasibility of unilateral carotid body resection in 15 patients with drug-resistant hypertension. The procedure proved to be safe and feasible. Overall, no change in blood pressure was found. However, 8 patients showed significant reductions in ambulatory blood pressure coinciding with decreases in sympathetic activity. The carotid body may be a novel target for treating an identifiable subpopulation of humans with hypertension
Gravitational Waves From Known Pulsars: Results From The Initial Detector Era
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom
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