Although a well‐known recommended treatment option, there are currently no studies that describe the detailed regimen of isotretinoin for the treatment of primary keratosis pilaris. Based on previous ...studies involving other hyperkeratotic disorders, this report describes a safe and effective treatment course of isotretinoin for severe keratosis pilaris.
Nosologically, Alzheimer disease may not be considered to be a single disorder in spite of a common clinical phenotype. Only a small proportion of about 5% to 10% of all Alzheimer cases is due to ...genetic mutations (type I) whereas the great majority of patients was found to be sporadic in origin. It may be assumed that susceptibility genes along with lifestyle risk factors contribute to the causation of the age-related sporadic Alzheimer disease (type II). In this context, the desensitization of the neuronal insulin receptor similar to not-insulin dependent diabetes mellitus may be of pivotal significance. This abnormality along with a reduction in brain insulin concentration is assumed to induce a cascade-like process of disturbances including cellular glucose, acetylcholine, cholesterol, and ATP associated with abnormalities in membrane pathology and the formation of both amyloidogenic derivatives and hyperphosphorylated tau protein. Sporadic Alzheimer disease may, thus, be considered to be the brain type of diabetes mellitus II. Experimental evidence is provided and discussed.
Abstract Humans produce two forms of cognitively complex vocalizations: speech and song. It is debated whether these differ based primarily on culturally specific, learned features, or if acoustical ...features can reliably distinguish them. We study the spectro-temporal modulation patterns of vocalizations produced by 369 people living in 21 urban, rural, and small-scale societies across six continents. Specific ranges of spectral and temporal modulations, overlapping within categories and across societies, significantly differentiate speech from song. Machine-learning classification shows that this effect is cross-culturally robust, vocalizations being reliably classified solely from their spectro-temporal features across all 21 societies. Listeners unfamiliar with the cultures classify these vocalizations using similar spectro-temporal cues as the machine learning algorithm. Finally, spectro-temporal features are better able to discriminate song from speech than a broad range of other acoustical variables, suggesting that spectro-temporal modulation—a key feature of auditory neuronal tuning—accounts for a fundamental difference between these categories.
Distractibility determines the propensity to have one's attention captured by irrelevant information; it relies on a balance between voluntary and involuntary attention. We report a cross-sectional ...study that uses the competitive attention test to characterize patterns of attention across the adult life span from 21 to 86 years old. Several distractibility components were measured in 186 participants distributed within seven age groups. Results indicate that distractibility components follow distinct trajectories with aging: Voluntary orienting remains stable from 21 to 86 years old, sustained attention decreases after 30 years old, distraction progressively increases between 26 and 86 years old, and impulsivity is lower in older compared to younger adults. Increased distractibility in older age thus seems to result from a dominance of involuntary over voluntary attention processes, whose detrimental effect on performance is partly compensated by enhanced motor control.
Public Significance StatementAttention is a multifaceted cognitive function allowing to focus and resist to distraction. While previous works have mostly compared two groups of young and older adults to investigate attention with aging, the present study characterizes the evolutive trajectories of several attention facets in participants from 21 to 86 years old, distributed in seven age groups. The results provide critical information to better understand how and when attention changes during normal aging. These findings can help the early detection of pathological attention decline, which can be a prodrome of neurodegenerative diseases.
It has been suggested that cross-frequency coupling in cortico-hippocampal networks enables the maintenance of multiple visuo-spatial items in working memory. However, whether this mechanism acts as ...a global neural code for memory retention across sensory modalities remains to be demonstrated. Intracranial EEG data were recorded while drug-resistant patients with epilepsy performed a delayed matched-to-sample task with tone sequences. We manipulated task difficulty by varying the memory load and the duration of the silent retention period between the to-be-compared sequences. We show that the strength of theta-gamma phase amplitude coupling in the superior temporal sulcus, the inferior frontal gyrus, the inferior temporal gyrus, and the hippocampus (i) supports the short-term retention of auditory sequences; (ii) decodes correct and incorrect memory trials as revealed by machine learning analysis; and (iii) is positively correlated with individual short-term memory performance. Specifically, we show that successful task performance is associated with consistent phase coupling in these regions across participants, with gamma bursts restricted to specific theta phase ranges corresponding to higher levels of neural excitability. These findings highlight the role of cortico-hippocampal activity in auditory short-term memory and expand our knowledge about the role of cross-frequency coupling as a global biological mechanism for information processing, integration, and memory in the human brain.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present photometric and spectroscopic observations of SN 2007if, an overluminous (M_V = -20.4), red (B-V = 0.16 at B-band maximum), slow-rising (t_rise = 24 days) type Ia supernova in a very faint ...(M_g = -14.10) host galaxy. A spectrum at 5 days past B-band maximum light is a direct match to the super-Chandrasekhar-mass candidate SN Ia 2003fg, showing Si II and C II at ~9000 km/s. A high signal-to-noise co-addition of the SN spectral time series reveals no Na I D absorption, suggesting negligible reddening in the host galaxy, and the late-time color evolution has the same slope as the Lira relation for normal SNe Ia. The ejecta appear to be well mixed, with no strong maximum in I-band and a diversity of iron-peak lines appearing in near-maximum-light spectra. SN2007 if also displays a plateau in the Si II velocity extending as late as +10 days, which we interpret as evidence for an overdense shell in the SN ejecta. We calculate the bolometric light curve of the SN and use it and the \ion{Si}{2} velocity evolution to constrain the mass of the shell and the underlying SN ejecta, and demonstrate that SN2007 if is strongly inconsistent with a Chandrasekhar-mass scenario. Within the context of a "tamped detonation" model appropriate for double-degenerate mergers, and assuming no host extinction, we estimate the total mass of the system to be 2.4 +/- 0.2 solar masses, with 1.6 +/- 0.1 solar masses of nickel-56 and with 0.3-0.5 solar masses in the form of an envelope of unburned carbon/oxygen. Our modeling demonstrates that the kinematics of shell entrainment provide a more efficient mechanism than incomplete nuclear burning for producing the low velocities typical of super-Chandrasekhar-mass SNeIa.
The star HD 144548 (=HIP 78977; TYP 6212-1273-1) has been known as a detached eclipsing binary and a bona-fide member of the Upper Scorpius OB association. Continuous photometry from the K2 mission ...on Campaign Two has revealed the presence of additional eclipses due to the presence of a third star in the system. These are explained by a system composed of the two previously known members of the eclipsing system (Ba and Bb) with a period of 1.63 d, orbiting around an F7-F8V star with a period of 33.945 ± 0.002 d in an eccentric orbit (eA = 0.2652 ± 0.0003). The timing of the eclipses of Ba and Bb reveals the same 33.9 d periodicity, which we interpret as the combination of a light time effect combined with dynamical perturbations on the close system. Here we combine radial velocities and analytical approximations for the timing of the eclipses to derive masses and radii for the three components of the system. We obtain a mass of 1.44 ± 0.04 M⊙ and radius of 2.41 ± 0.03 R⊙ for the A component, and almost identical masses and radii of about 0.96 M⊙ and 1.33 R⊙ for each of the two components of the close binary. HD 144548 is the first triply eclipsing system for which radial velocities of all components could be measured.
Regular use of marijuana during adolescence enhances the risk of long‐lasting neurobiological changes in adulthood. The present study was aimed at assessing the effect of long‐term administration of ...the synthetic cannabinoid WIN55212.2 during adolescence in young adult mice. Adolescent mice aged 5 weeks were subjected daily to the pharmacological action of WIN55212.2 for 3 weeks and were then left undisturbed in their home cage for a 5‐week period and finally evaluated by behavioral testing. Mice that received the drug during adolescence showed memory impairment in the Morris water maze, as well as a dose‐dependent memory impairment in fear conditioning. In addition, the administration of 3 mg/kg WIN55212.2 in adolescence increased adult hippocampal AEA levels and promoted DNA hypermethylation at the intragenic region of the intracellular signaling modulator Rgs7, which was accompanied by a lower rate of mRNA transcription of this gene, suggesting a potential causal relation. Although the concrete mechanisms underlying the behavioral observations remain to be elucidated, we demonstrate that long‐term administration of 3 mg/kg of WIN during adolescence leads to increased endocannabinoid levels and altered Rgs7 expression in adulthood and establish a potential link to epigenetic changes.
Adolescent mice were subjected daily to WIN55212.2, then left undisturbed, and finally evaluated by behavioral testing at adulthood. Mice that received the drug during adolescence showed memory impairment, higher endocannabinoid levels and altered Rgs7 expression in adulthood, establishing a potential link to epigenetic changes.
It is discussed that Alzheimer disease does not form a nosologic entity. 5 to 10% of all Alzheimer cases are due to inherited abnormalities on chromosomes 1, or 14, or 21, whereas the majority of ...90–95% is sporadic in origin. Age-related changes in the composition of membranes and in glucose/energy metabolism along with a sympathetic tone in the brain are assumed to be cellular/molecular risk factors for this disease. In its pathogenesis, the desensitization of the neuronal insulin receptor similar to non-insulin dependent diabetes mellitus may be of pivotal significance. This abnormality along with a reduction in insulin concentration is assumed to induce a cascade-like process of disturbances including decreases in cellular glucose, acetylcholine, cholesterol, and ATP, associated with changes in the metabolism of amino acids and fatty acids. There is evidence that the reductions in the availability of both glucose/energy and insulin contribute to the formation of amyloidogenic derivatives and hyperphosphorylated tau protein. This may indicate that the amyloid cascade hypothesis in not valid for sporadic Alzheimer disease but that the formation of both, amyloidogenic derivatives and hyperphosphorylated tau protein is downstream the origin of this neurodegenerative disease.
Context.
The extreme contrast ratios between stars and their planets at optical wavelengths make it challenging to isolate the light reflected by exoplanet atmospheres. Yet, these reflective ...properties reveal key processes occurring in the atmospheres, and they also span wavelengths that include the potential O
2
biosignature. High resolution cross-correlation spectroscopy (HRCCS) offers a robust avenue for developing techniques to extract exoplanet reflection spectra.
Aims.
We aimed to extract the optical reflected light spectrum of the non-transiting hot Jupiter 51 Pegasi b by adapting techniques designed to remove tellurics in infrared HRCCS to instead remove optical stellar lines. Importantly, we investigated the as of yet neglected impact of the broadening of the reflected host star spectrum due to the difference between the stellar rotation and the planet’s orbital velocity.
Methods.
We used 484,
R
= 115 000 optical spectra of 51 Pegasi b from HARPS-N and HARPS, which we aligned to the exact stellar rest frame, in order to effectively remove the contaminating host star. However, some stellar residuals remained, likely due to stellar activity. We cross-correlated with an appropriately broadened synthetic stellar model to search for the planet’s Doppler-shifting spectrum.
Results.
We detect no significant reflected light from 51 Pegasi b, and report a signal-to-noise (
S
∕
N
) = 3 upper limit on the contrast ratio of 76.0 ppm (7.60 × 10
−5
) when including broadening, and 24.0 ppm (2.40 × 10
−5
) without. These upper limits rule out radius and albedo combinations of previously claimed detections.
Conclusions.
Broadening can significantly impact the ability of HRCCS to extract reflected light spectra and it must be considered when determining the contrast ratio, radius, and albedo of the planet. Asynchronous systems (
P
rot,⋆
≠
P
orb
) are most affected, including most hot Jupiters as well as Earth-size planets in the traditional habitable zones of some M-dwarfs.
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