The Effect of Central Chemoreceptors on the Peripheral Respiratory Chemoreflex Response to Hypoxia in Humans

We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (PCO2) to determine the form of the relationship between PChS and central PCO2. Twenty participants completed three repetitions of modified rebreathing tests with end-tidal PO2 (PETO2) clamped at 150, 70, 60, and 45 mmHg. PChS was computed at 1-mmHg intervals of PETCO2 as follows: the differences in V̇E between the three hypoxic profiles and the hyperoxic profile (∆V̇E) were calculated; three ∆V̇E values were plotted against corresponding calculated oxyhemoglobin saturation (SCO2); and linear regression determined PChS (L∙min-1∙mmHg-1∙%SCO2-1). These processing steps were repeated at each PETCO2 to produce the PChS vs. isocapnic PCO2 relationship which was fitted with linear and polynomial functions. Chemoreflex sensitivity (V̇ES) rose (PCO2 fell progressively (pETCO2 and this relationship was best described by a liner model in 15 of the 20 individuals, indicative of an additive interaction

Design, construction, and test of the Gas Pixel Detectors for the IXPE mission

Due to be launched in late 2021, the Imaging X-Ray Polarimetry Explorer (IXPE) is a NASA Small Explorer mission designed to perform polarization measurements in the 2-8 keV band, complemented with imaging, spectroscopy and timing capabilities. At the heart of the focal plane is a set of three polarization-sensitive Gas Pixel Detectors (GPD), each based on a custom ASIC acting as a charge-collecting anode. In this paper we shall review the design, manufacturing, and test of the IXPE focal-plane detectors, with particular emphasis on the connection between the science drivers, the performance metrics and the operational aspects. We shall present a thorough characterization of the GPDs in terms of effective noise, trigger efficiency, dead time, uniformity of response, and spectral and polarimetric performance. In addition, we shall discuss in detail a number of instrumental effects that are relevant for high-level science analysis -- particularly as far as the response to unpolarized radiation and the stability in time are concerned.Comment: To be published in Astroparticle Physic

Global overview of the management of acute cholecystitis during the COVID-19 pandemic (CHOLECOVID study)

Background: This study provides a global overview of the management of patients with acute cholecystitis during the initial phase of the COVID-19 pandemic. Methods: CHOLECOVID is an international, multicentre, observational comparative study of patients admitted to hospital with acute cholecystitis during the COVID-19 pandemic. Data on management were collected for a 2-month study interval coincident with the WHO declaration of the SARS-CoV-2 pandemic and compared with an equivalent pre-pandemic time interval. Mediation analysis examined the influence of SARS-COV-2 infection on 30-day mortality. Results: This study collected data on 9783 patients with acute cholecystitis admitted to 247 hospitals across the world. The pandemic was associated with reduced availability of surgical workforce and operating facilities globally, a significant shift to worse severity of disease, and increased use of conservative management. There was a reduction (both absolute and proportionate) in the number of patients undergoing cholecystectomy from 3095 patients (56.2 per cent) pre-pandemic to 1998 patients (46.2 per cent) during the pandemic but there was no difference in 30-day all-cause mortality after cholecystectomy comparing the pre-pandemic interval with the pandemic (13 patients (0.4 per cent) pre-pandemic to 13 patients (0.6 per cent) pandemic; P = 0.355). In mediation analysis, an admission with acute cholecystitis during the pandemic was associated with a non-significant increased risk of death (OR 1.29, 95 per cent c.i. 0.93 to 1.79, P = 0.121). Conclusion: CHOLECOVID provides a unique overview of the treatment of patients with cholecystitis across the globe during the first months of the SARS-CoV-2 pandemic. The study highlights the need for system resilience in retention of elective surgical activity. Cholecystectomy was associated with a low risk of mortality and deferral of treatment results in an increase in avoidable morbidity that represents the non-COVID cost of this pandemic

The Imaging X-ray Polarimetry Explorer (IXPE): Technical Overview

The Imaging X-ray Polarimetry Explorer (IXPE) will expand the information space for study of cosmic sources, by adding linear polarization to the properties (time, energy, and position) observed in x-ray astronomy. Selected in 2017 January as a NASA Astrophysics Small Explorer (SMEX) mission, IXPE will be launched into an equatorial orbit in 2021. The IXPE mission will provide scientifically meaningful measurements of the x-ray polarization of a few dozen sources in the 2-8 keV band, including polarization maps of several x-ray-bright extended sources and phase-resolved polarimetry of many bright pulsating x-ray sources

Knowledge Priorities on Climate Change and Water in the Upper Indus Basin: A Horizon Scanning Exercise to Identify the Top 100 Research Questions in Social and Natural Sciences

River systems originating from the Upper Indus Basin (UIB) are dominated by runoff from snow and glacier melt and summer monsoonal rainfall. These water resources are highly stressed as huge populations of people living in this region depend on them, including for agriculture, domestic use, and energy production. Projections suggest that the UIB region will be affected by considerable (yet poorly quantified) changes to the seasonality and composition of runoff in the future, which are likely to have considerable impacts on these supplies. Given how directly and indirectly communities and ecosystems are dependent on these resources and the growing pressure on them due to ever-increasing demands, the impacts of climate change pose considerable adaptation challenges. The strong linkages between hydroclimate, cryosphere, water resources, and human activities within the UIB suggest that a multi- and inter-disciplinary research approach integrating the social and natural/environmental sciences is critical for successful adaptation to ongoing and future hydrological and climate change. Here we use a horizon scanning technique to identify the Top 100 questions related to the most pressing knowledge gaps and research priorities in social and natural sciences on climate change and water in the UIB. These questions are on the margins of current thinking and investigation and are clustered into 14 themes, covering three overarching topics of ‘governance, policy, and sustainable solutions’, ‘socioeconomic processes and livelihoods’, and ‘integrated Earth System processes’. Raising awareness of these cutting-edge knowledge gaps and opportunities will hopefully encourage researchers, funding bodies, practitioners, and policy makers to address them

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Ascorbic acid decreases morphine self-administration and withdrawal symptoms in rats

Recent studies have indicated that the glutamatergic system is involved in the motivational aspects during the initiation of drug selfadministration. Ascorbic acid (AA), an antioxidant vitamin, is released from glutamatergic neurons, and it modulates the synaptic action of dopamine and glutamate. In this study the AA effects on the self-administration of morphine and on the morphine withdrawal syndrome have been investigated. Wistar rats were allowed to self-administer morphine (1 mg/infusion) during 10 consecutive days for 2 h/session. The number of lever pressings was recorded. An intrapritoneal AA injection (500 mg/kg, i.p.), 30 min before morphine self-administration produced a significant decrease in the initiation of morphine self administration during all sessions. After the last test session morphine withdrawal symptom signs (MWS) were recorded after naloxone precipitation. Most of MWS (but not all) were decreased by AA application. In conclusion, AA may change the motivational processes underlying the morphine self-administration

The effects of Quinpirole and Sulpiride on conflict responses in rat

In this investigation wer studied the effect of dopaminergic system on the conflict behavior in rat, using vogel’s test. The related drugs were injected intraperitonealy (IP), and produced the following results:Diazepam at doses of 0.5 and 1 mg/kg increased the lick –shock responses in the Vogel’s thest. Quinpirole (D2-Agnosit), at doses of 0.1 and 10 mg/kg, increased the confict responses, wheraes suplpirde (D2 Antagonist) did not affect them.Apomorphine (D1 and D2 agonist) had a biphasic effect on the conflict responses. This drug decreased the number of shoks at low dose (0.01 mg/kg) while increased them at high dose (1 mg/kg). Haloperidol at dose of 1 mg/kg reduced the conflit responses significantly. Administration of both sulpiride (30 mg/kg) and quinpirole (10 mg/kg) together, increase the confict responses.These results suggest that D2-receptor agonist drugs may exert anixolytic and D2-receptor antagonists may produce anxiogenic effects in rat