Hindbrain mineralocorticoid mechanisms on sodium appetite Formenti, Silmara; Bassi, Mirian; Nakamura, Natália B ...
American journal of physiology. Regulatory, integrative and comparative physiology
304, Številka:
3
Journal Article
Recenzirano
Aldosterone acting on the brain stimulates sodium appetite and sympathetic activity by mechanisms that are still not completely clear. In the present study, we investigated the effects of chronic ...infusion of aldosterone and acute injection of the mineralocorticoid receptor (MR) antagonist RU 28318 into the fourth ventricle (4th V) on sodium appetite. Male Wistar rats (280-350 g) with a stainless-steel cannula in either the 4th V or lateral ventricle (LV) were used. Daily intake of 0.3 M NaCl increased to 46 ± 15 and 130 ± 6 ml/24 h after 6 days of infusion of 10 and 100 ng/h of aldosterone into the 4th V (intake with vehicle infusion: 2 ± 1 ml/24 h). Water intake fell slightly and not consistently, and food intake was not affected by aldosterone. Sodium appetite induced by diuretic (furosemide) combined with 24 h of a low-sodium diet fell from 12 ± 1.7 ml/2 h to 5.6 ± 0.8 ml/2 h after injection of the MR antagonist RU 28318 (100 ng/2 μl) into the 4th V. RU 28318 also reduced the intake of 0.3 M NaCl induced by 9 days of a low-sodium diet from 9.5 ± 2.6 ml/2 h to 1.2 ± 0.6 ml/2 h. Infusion of 100 or 500 ng/h of aldosterone into the LV did not affect daily intake of 0.3 M NaCl. The results are functional evidence that aldosterone acting on MR in the hindbrain activates a powerful mechanism involved in the control of sodium appetite.
We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov Observatory, a wide field-of-view observatory capable of detecting ...gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons.
The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report ...the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera–electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera–electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.
Highlights • Apnea in conscious rats induces sympathetic and cardiac vagal activation. • Apnea induces Fos expression in the catecholaminergic groups in the brain stem. • Inactivation of carotid ...chemoreceptors reduced apnea-induced Fos expression in the caudal NTS. • Neuronal activation seems to occur in areas that integrate afferent signals elicited by apnea.
Abstract Lack of dystrophin is known to reduce several cerebral fiber systems. To investigate if the loss of fibers is progressive, we analyzed projections of the trigeminal sensory system to the red ...nucleus in 3, 6, and 12 month old dystrophin-deficient mdx mice. The retrograde tracer fluorogold was injected in the magnocellular part of the red nucleus, and the number of labeled neurons in the oral part of the spinal trigeminal nucleus (Sp5O) was counted. We found that the number of labeled Sp5O neurons was reduced by 50% in mdx mice compared to age-matched control mice. The number of labeled Sp5O neurons did not change significantly between 3 and 12 months neither in mdx nor in control mice. In addition, the number of labeled neurons in the interstitial system of the trigeminal nerve was reduced by 43% in mdx mice. We conclude that fiber loss did not continue beyond the age of 3 months. Our data suggest that lack of full-length dystrophin impairs neuronal migration or axonal outgrowth, or increases neuronal death during fetal or early life.
The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV ...instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field of view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above ∼1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form . The data is well fitted with values of = 2.63 0.03, β = 0.15 0.03, and when E0 is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be 50% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC all-sky survey will be the deepest survey of the northern sky ever conducted in the multi-TeV band.
We present the first catalog of TeV gamma-ray sources realized with data from the newly completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV ...telescope currently in operation, with a one-year survey sensitivity of ∼5%-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma-ray energies between hundreds of GeV and tens of TeV. HAWC is located in Mexico, at a latitude of 19° N, and was completed in 2015 March. Here, we present the 2HWC catalog, which is the result of the first source search performed with the complete HAWC detector. Realized with 507 days of data, it represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected number of false detections of 0.5 due to background fluctuation. Out of these sources, 19 are new sources that are not associated with previously known TeV sources (association criteria: <0 5 away). The source list, including the position measurement, spectrum measurement, and uncertainties, is reported, then each source is briefly discussed. Of the 2HWC associated sources, 10 are reported in TeVCat as PWN or SNR: 2 as blazars and the remaining eight as unidentified.
We present a new catalog of TeV gamma-ray sources using 1523 days of data from the High-Altitude Water Cherenkov (HAWC) Observatory. The catalog represents the most sensitive survey of the northern ...gamma-ray sky at energies above several TeV, with three times the exposure compared to the previous HAWC catalog, 2HWC. We report 65 sources detected at ≥5 significance, along with the positions and spectral fits for each source. The catalog contains eight sources that have no counterpart in the 2HWC catalog, but are within 1° of previously detected TeV emitters, and 20 sources that are more than 1° away from any previously detected TeV source. Of these 20 new sources, 14 have a potential counterpart in the fourth Fermi Large Area Telescope catalog of gamma-ray sources. We also explore potential associations of 3HWC sources with pulsars in the Australia Telescope National Facility (ATNF) pulsar catalog and supernova remnants in the Galactic supernova remnant catalog.
The Pierre Auger Cosmic Ray Observatory Aab, A.; Abreu, P.; Aglietta, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2015, Letnik:
798, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world׳s largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and ...characteristics of cosmic rays above 1017eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water Cherenkov particle detector stations spread over 3000km2 overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5km2, 61-detector infilled array with 750m spacing. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000km2sryr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Observatory.
PDF
