Major depressive disorder (MDD) is characterized by alterations in brain function that are identifiable also during the brain's 'resting state'. One functional network that is disrupted in this ...disorder is the default mode network (DMN), a set of large-scale connected brain regions that oscillate with low-frequency fluctuations and are more active during rest relative to a goal-directed task. Recent studies support the idea that the DMN is not a unitary system, but rather is composed of smaller and distinct functional subsystems that interact with each other. The functional relevance of these subsystems in depression, however, is unclear.
Here, we investigated the functional connectivity of distinct DMN subsystems and their interplay in depression using resting-state functional magnetic resonance imaging.
We show that patients with MDD exhibit increased within-network connectivity in posterior, ventral and core DMN subsystems along with reduced interplay from the anterior to the ventral DMN subsystems.
These data suggest that MDD is characterized by alterations of subsystems within the DMN as well as of their interactions. Our findings highlight a critical role of DMN circuitry in the pathophysiology of MDD, thus suggesting these subsystems as potential therapeutic targets.
Spin-orbit coupling is a fundamental interaction in solids that can induce a broad range of unusual physical properties, from topologically non-trivial insulating states to unconventional pairing in ...superconductors1, 2, 3, 4, 5, 6, 7. In iron-based superconductors its role has, so far, not been considered of primary importance, with models based on spin- or orbital fluctuations pairing being used most widely8, 9, 10. Using angle-resolved photoemission spectroscopy, we directly observe a sizeable spin-orbit splitting in all the main members of the iron-based superconductors. We demonstrate that its impact on the low-energy electronic structure and details of the Fermi surface topology is stronger than that of possible nematic ordering11, 12, 13. The largest pairing gap is supported exactly by spin-orbit-coupling-induced Fermi surfaces, implying a direct relation between this interaction and the mechanism of high-temperature superconductivity.
Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been ...possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 2014 May 14 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm−3 pc, giving an upper limit on source redshift of z ≲ 0.5. FRB 140514 was found to be 21 ± 7 per cent (3σ) circularly polarized on the leading edge with a 1σ upper limit on linear polarization <10 per cent. We conclude that this polarization is intrinsic to the FRB. If there was any intrinsic linear polarization, as might be expected from coherent emission, then it may have been depolarized by Faraday rotation caused by passing through strong magnetic fields and/or high-density environments. FRB 140514 was discovered during a campaign to re-observe known FRB fields, and lies close to a previous discovery, FRB 110220; based on the difference in DMs of these bursts and time-on-sky arguments, we attribute the proximity to sampling bias and conclude that they are distinct objects. Follow-up conducted by 12 telescopes observing from X-ray to radio wavelengths was unable to identify a variable multiwavelength counterpart, allowing us to rule out models in which FRBs originate from nearby (z < 0.3) supernovae and long duration gamma-ray bursts.
Lead-halide perovskite (LHP) semiconductors are emergent optoelectronic materials with outstanding transport properties which are not yet fully understood. We find signatures of large polaron ...formation in the electronic structure of the inorganic LHP CsPbBr3 by means of angle-resolved photoelectron spectroscopy. The experimental valence band dispersion shows a hole effective mass of 0.26±0.02 me, 50% heavier than the bare mass m0=0.17 me predicted by density functional theory. Calculations of the electron-phonon coupling indicate that phonon dressing of the carriers mainly occurs via distortions of the Pb-Br bond with a Fröhlich coupling parameter α=1.81. A good agreement with our experimental data is obtained within the Feynman polaron model, validating a viable theoretical method to predict the carrier effective mass of LHPs ab initio.
Context.
High-redshift quasars signpost the early accretion history of the Universe. The penetrating nature of X-rays enables a less absorption-biased census of the population of these luminous and ...persistent sources compared to optical/near-infrared colour selection. The ongoing SRG/eROSITA X-ray all-sky survey offers a unique opportunity to uncover the bright end of the high-
z
quasar population and probe new regions of colour parameter space.
Aims.
We searched for high-
z
quasars within the X-ray source population detected in the contiguous ~140 deg
2
field observed by eROSITA during the performance verification phase. With the purpose of demonstrating the unique survey science capabilities of eROSITA, this field was observed at the depth of the final all-sky survey. The blind X-ray selection of high-redshift sources in a large contiguous, near-uniform survey with a well-understood selection function can be directly translated into constraints on the X-ray luminosity function (XLF), which encodes the luminosity-dependent evolution of accretion through cosmic time.
Methods.
We collected the available spectroscopic information in the eFEDS field, including the sample of all currently known optically selected
z
> 5.5 quasars and cross-matched secure Legacy DR8 counterparts of eROSITA-detected X-ray point-like sources with this spectroscopic sample.
Results.
We report the X-ray detection of eFEDSU J083644.0+005459, an eROSITA source securely matched to the well-known quasar SDSS J083643.85+005453.3 (
z
= 5.81). The soft X-ray flux of the source derived from eROSITA is consistent with previous
Chandra
observations. The detection of SDSS J083643.85+005453.3 allows us to place the first constraints on the XLF at
z
> 5.5 based on a secure spectroscopic redshift. Compared to extrapolations from lower-redshift observations, this favours a relatively flat slope for the XLF at
z
~ 6 beyond
L
*
, the knee in the luminosity function. In addition, we report the detection of the quasar with LOFAR at 145 MHz and ASKAP at 888 MHz. The reported flux densities confirm a spectral flattening at lower frequencies in the emission of the radio core, indicating that SDSS J083643.85+005453.3 could be a (sub-) gigahertz peaked spectrum source. The inferred spectral shape and the parsec-scale radio morphology of SDSS J083643.85+005453.3 indicate that it is in an early stage of its evolution into a large-scale radio source or confined in a dense environment. We find no indications for a strong jet contribution to the X-ray emission of the quasar, which is therefore likely to be linked to accretion processes.
Conclusions.
Our results indicate that the population of X-ray luminous AGNs at high redshift may be larger than previously thought. From our XLF constraints, we make the conservative prediction that eROSITA will detect ~90 X-ray luminous AGNs at redshifts 5.7 <
z
< 6.4 in the full-sky survey (De+RU). While subject to different jet physics, both high-redshift quasars detected by eROSITA so far are radio-loud; a hint at the great potential of combined X-ray and radio surveys for the search of luminous high-redshift quasars.
Excessive smartphone use (ESU), that is, a pattern of smartphone use that shows specific features of addictive behavior, has increasingly attracted societal and scientific interest in the past years. ...On the neurobiological level, ESU has recently been related to structural and functional variation in reward and salience processing networks, as shown by, for example, aberrant patterns of neural activity elicited by specific smartphone cues.
Expanding on these findings, using cross-modal correlations of magnetic resonance imaging (MRI)-based measures with nuclear imaging-derived estimates, we aimed at identifying neurochemical pathways that are related to ESU.
Cross-modal correlations between functional MRI data derived from a cue-reactivity task administered in persons with and without ESU and specific PET/SPECT receptor probability maps.
The endogenous mu-opioid receptor (MOR) system was found to be significantly (FDR-corrected) correlated with fMRI data, and z-transformed correlation coefficients showed an association (albeit nonsignificant after FDR-correction) between MOR and the Smartphone Addiction Inventory "withdrawal" dimension.
We could identify the MOR system as a neurochemical pathway associated with ESU. The MOR system is closely linked to the reward system, which has been recognized as a key player in addictive disorders. Together with its potential link to withdrawal, the MOR system hints toward a biologically highly relevant marker, which should be taken into consideration in the ongoing scientific discussion on technology-related addictive behaviors.
Tibial bone stress injury is a common overuse injury experienced by runners, which results from repetitive tissue forces. Wearable sensor systems (wearables) that monitor tibial forces could help ...understand and reduce injury incidence. However, there are currently no validated wearables that monitor tibial bone forces. Previous work using simulated wearables demonstrated accurate tibial force estimates by combining a shoe-worn inertial measurement unit (IMU) and pressure insole with a trained algorithm. This study aimed assessed how accurately tibial bone forces could be estimated with existing wearables. Nine recreational runners ran at a series of different speeds and slopes, and with various stride patterns. Shoe-worn IMU and insole data were input into a trained algorithm to estimate peak tibial force. We found an average error of 5.7% in peak tibial force estimates compared with lab-based estimates calculated using motion capture and a force instrumented treadmill. Insole calibration procedures were essential to achieving accurate tibial force estimates. We concluded that a shoe-worn, multi-sensor system is a promising approach to monitoring tibial bone forces in running. This study adds to the literature demonstrating the potential of wearables to monitor musculoskeletal forces, which could positively impact injury prevention, and scientific understanding.
Background: The hypermetabolic response to severe burn is characterized by muscle protein catabolism. Current opinion states that the hypermetabolic state resolves soon after complete wound closure. ...Clinically, we have witnessed that burned children appear to be hypermetabolic and catabolic long after full healing of their wounds. Our goal in this study was to determine scientifically if burn-associated hypermetabolism persists after full wound healing. Methods: To determine the duration of muscle catabolism and systemic hypermetabolism after severe burn in children, patients with > 40% total body surface area burns were enrolled in a prospective, longitudinal study; resting energy expenditure was measured by indirect calorimetry, muscle protein kinetics were determined by using stable isotopic methodology, and body composition was measured by dual-energy x-ray absorptiometry imaging. Data were collected at 6, 9, and 12 months after injury. Results: The mean total body surface area burned was 65% ± 13%, and the mean age was 7.6 ± 1.5 years. Resting energy expenditure was elevated above the predicted age-matched levels from the Harris-Benedict equation and incrementally declined throughout the 12-month study. The net protein balance and lean mass reflected catabolic persistence at 6 and 9 months after severe burn. Between 9 and 12 months, protein breakdown decreased, net protein balance improved, and lean body mass increased. Conclusions: In severely burned children, hypermetabolism and catabolism remain exaggerated for at least 9 months after injury. This suggests that therapeutic attempts to manipulate the catabolic and hypermetabolic response to severe injury should be continued long after injury. (Surgery 2000;128:312-9.)
Reversal of Catabolism by Beta-Blockade after Severe Burns Herndon, David N; Hart, David W; Wolf, Steven E ...
New England journal of medicine/The New England journal of medicine,
10/2001, Letnik:
345, Številka:
17
Journal Article
Recenzirano
Odprti dostop
Patients with severe burns have catecholamine-mediated hypermetabolism, including pronounced muscle-protein catabolism, that adversely affects recovery. In a prospective, randomized study, 13 ...children with severe burns were given oral propranolol for up to four weeks in an attempt to interrupt this process, and 12 served as controls. Beta-blockade decreased resting energy expenditure and increased net muscle-protein balance by 82 percent, as compared with a 27 percent decrease in net muscle-protein balance in the control group.
In a prospective, randomized study, children with severe burns were given propranolol to decrease hypermetabolism and reverse muscle-protein catabolism.
The hypermetabolic response to severe burns is associated with increased energy expenditure and the release of substrate from protein and fat stores. After severe trauma, the rate of protein catabolism is increased, leading to the loss of lean body mass and muscle wasting.
1
,
2
Muscle proteolysis continues for at least nine months after severe burns,
3
thus increasing the likelihood of delays in rehabilitation, other complications, and death.
4
Endogenous catecholamines are primary mediators of the hypermetabolic response to trauma or burns.
5
,
6
Shortly after severe trauma or burns, plasma catecholamine levels increase as much as 10-fold.
7
,
8
This systemic response to . . .
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