Alzheimer disease affects millions of people worldwide. The neuropathologic process underlying this disease begins years, if not decades, before the onset of memory decline. Recent advances in ...neuroimaging suggest that it is now possible to detect Alzheimer-associated neuropathologic changes well before dementia onset. Here, we evaluate the role of recently developed in vivo biomarkers in the clinical evaluation of Alzheimer disease. We discuss how assessment strategies might incorporate neuroimaging markers to better inform patients, families, and clinicians when memory impairment prompts a search for diagnosis and management options.
Additive friction stir deposition (AFSD) is a solid-state additive manufacturing and repair process that provides a way to rapidly repair and/or fabricate components using similar feedstocks as the ...repaired substrate without melting the feedstock or substrate material. In AFSD, the material is deposited using a high-shear thermomechanical deposition process resulting in a near-net shape product. In this work, we evaluate the viability of the AFSD process for depositing stainless steel 304L (SS304L) feedstock onto the same stainless steel substrate. This is considered as a potential crack repair or cladding repair methodology, especially at high deposition rates, for dry cask storage containers (DCSCs) used for spent nuclear fuel. The SS304L DCSCs are susceptible to chloride-induced pitting and stress corrosion cracking, which demands periodic maintenance and repair. Therefore, AFSD, due to its non-melting deposition process provides low heat input and wrought-like mechanical properties, is evaluated here for SS304L through a combined microstructural and mechanical analysis of the deposited layers and substrate material. Specifically, electron backscatter diffraction identified equiaxed grains with a mean size of ~ 3–4 µm in the deposit, similar to the average grain size of 3.5 µm in the wrought substrate, with regions of refined grains near the tool/deposit and deposit/substrate interface. The microhardness at the mid-thickness of the deposit (280 Hv) is comparable to the wrought substrate hardness of 278 Hv. The dense, wrought-like SS304L deposit suggests further applying the promising AFSD technique to repair structures like the DCSCs.
Results are presented from the Rum Creek fire during the California Fire Dynamics Experiment (CalFiDE). An instrumented payload aboard the NOAA Twin Otter (TO) aircraft, which included a scanning ...micro‐pulsed Doppler lidar (DL) and in situ chemistry packages, was used to address the evolution of a buoyant plume jet (BPJ) and transport dynamics over the southwest corner of the fire between 09/01/2022 and 09/02/2022. An approach previously developed to isolate updrafts was modified to account for the Gaussian core structure when addressing the evolution of the updraft, plume‐top entrainment, lateral entrainment, and the role of fire‐atmosphere interactions on the characteristics of the BPJ during four overpasses. A persistent cross‐valley flow leading up to the BPJ was observed for all four overpasses, with flow enhancement during the second overpass that coincided with changes in the BPJ structure and turbulence characteristics surrounding the BPJ. Length scales and entrainment rates were estimated at the lateral edges and the top of the plume. In the case of the latter, an analytical form of the BPJ profile above the vertical velocity maximum of the updraft was derived using a simplified form of the vertical momentum equation following a partial budget analysis that accounted for plume‐top entrainment and the boundary layer (BL) inversion. Velocity core strength and characteristics were analyzed away from the updraft with similar relationships between depth‐to‐widths of velocity cores found in a forthcoming study focused on wildfire plumes.
Plain Language Summary
The goal of the California Fire Dynamics Experiment (CalFiDE) during the fall of 2022 was to survey wildfire dynamics and impacts on air quality over areas historically affected by wildfires. The Rum Creek fire, which occurred west of Medford, Oregon, was one of several fires observed using data collected aboard the NOAA Twin Otter (TO) aircraft. In this study, we focused on a smoke plume at the southwest corner of the fire that featured strong upward motion. Multiple flyovers of this plume led to an analysis of how the plume changed with time, and how the conditions surrounding the plume supported its development. The work presented details the internal structure of the plume and the influence of background winds on the evolution of the plume, which has implications for understanding the transport of smoke away from the fire.
Key Points
Airborne Doppler lidars are capable of resolving small scale dynamics over short distances spanning the width of the fireline
Complex interactions between fire‐induced updrafts and the surrounding atmosphere can lead to non‐ideal representation of the updraft profile
Terrain and fire‐modified winds are important for updraft evolution and transport dynamics
RAIN IN SHALLOW CUMULUS OVER THE OCEAN Rauber, Robert M.; Stevens, Bjorn; Ochs, Harry T. ...
Bulletin of the American Meteorological Society,
12/2007, Letnik:
88, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Shallow, maritime cumuli are ubiquitous over much of the tropical oceans, and characterizing their properties is important to understanding weather and climate. The Rain in Cumulus over the Ocean ...(RICO) field campaign, which took place during November 2004–January 2005 in the trades over the western Atlantic, emphasized measurements of processes related to the formation of rain in shallow cumuli, and how rain subsequently modifies the structure and ensemble statistics of trade wind clouds. Eight weeks of nearly continuous S-band polarimetric radar sampling, 57 flights from three heavily instrumented research aircraft, and a suite of ground- and ship-based instrumentation provided data on trade wind clouds with unprecedented resolution. Observational strategies employed during RICO capitalized on the advances in remote sensing and other instrumentation to provide insight into processes that span a range of scales and that lie at the heart of questions relating to the cause and effects of rain from shallow maritime cumuli.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Objectives The objectives were to determine the time course for ovarian failure in rats caused by 4-vinylcyclohexene diepoxide (VCD) and develop a model for ovarian cancer in which ovarian ...neoplasms were chemically induced in an animal that was follicle depleted, but retained residual ovarian tissue. Methods Initially, female Fisher 344 rats were treated with VCD (to induce ovarian failure) or vehicle control (sesame oil). Three or 6 months after treatment, ovaries were collected and processed for histological evaluation for confirmation of ovarian failure. A further set of female rats was assigned to four groups exposed to combinations of vehicle control, VCD and/or DMBA (directly applied to the ovary) in a novel model for examining early stages of ovarian neoplasia. Results Three and 6 months following VCD dosing there was a significant reduction of ovarian weight and follicle number. Treatment with DMBA subsequent to VCD resulted in tumors in 42% of animals at 3 months and 57% at 5 months. All neoplasms were classified Sertoli–Leydig cell tumors (SLCT). No tumor occurred in animals treated with vehicle or DMBA alone. Conclusions These studies demonstrate that the VCD-treated rat can be used as a model for peri- and post-menopause. DMBA induction of ovarian neoplasms was greater in those rats treated with VCD. Whether this increase was due to tumor initiation by VCD or was the result of ovarian failure cannot be distinguished from these results. This represents the only animal model to date for sex cord stromal tumors.
Given the diversity of stimuli encountered in daily life, a variety of strategies must be used for learning new information. Relating and encoding visual and verbal stimuli into memory has been ...probed using various tasks and stimulus types. Engagement of specific subsequent memory and cortical processing regions depends on the stimulus modality of studied material; however, it remains unclear whether different encoding strategies similarly influence regional activity when stimulus type is held constant. In this study, participants encoded object pairs using a visual or verbal associative strategy during fMRI, and subsequent memory was assessed for pairs encoded under each strategy. Each strategy elicited distinct regional processing and subsequent memory effects: middle/superior frontal, lateral parietal, and lateral occipital for visually associated pairs and inferior frontal, medial frontal, and medial occipital for verbally associated pairs. This regional selectivity mimics the effects of stimulus modality, suggesting that cortical involvement in associative encoding is driven by strategy and not simply by stimulus type. The clinical relevance of these findings, probed in a patient with a recent aphasic stroke, suggest that training with strategies utilizing unaffected cortical regions might improve memory ability in patients with brain damage.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT Recent intensive Swift monitoring of the Seyfert 1 galaxy NGC 5548 yielded 282 usable epochs over 125 days across six UV/optical bands and the X-rays. This is the densest extended active ...galactic nucleus (AGN) UV/optical continuum sampling ever obtained, with a mean sampling rate <0.5 day. Approximately daily Hubble Space Telescope UV sampling was also obtained. The UV/optical light curves show strong correlations ( ) and the clearest measurement to date of interband lags. These lags are well-fit by a wavelength dependence, with a normalization that indicates an unexpectedly large disk radius of lt-day at 1367 , assuming a simple face-on model. The U band shows a marginally larger lag than expected from the fit and surrounding bands, which could be due to Balmer continuum emission from the broad-line region as suggested by Korista and Goad. The UV/X-ray correlation is weaker ( ) and less consistent over time. This indicates that while Swift is beginning to measure UV/optical lags in general agreement with accretion disk theory (although the derived size is larger than predicted), the relationship with X-ray variability is less well understood. Combining this accretion disk size estimate with those from quasar microlensing studies suggests that AGN disk sizes scale approximately linearly with central black hole mass over a wide range of masses.
The outcome of the first pilot study of liver-directed gene therapy is reported here. Five patients with homozygous familial hypercholesterolaemia (FH) ranging in age from 7 to 41 years were ...enrolled; each patient tolerated the procedure well without significant complications. Transgene expression was detected in a limited number of hepatocytes of liver tissue harvested four months after gene transfer from all five patients. Significant and prolonged reductions in low density lipoprotein (LDL) cholesterol were demonstrated in three of five patients; in vivo LDL catabolism was increased 53% following gene therapy in a receptor negative patient, who realized a reduction in serum LDL equal to approximately 150 mg dl-1. This study demonstrates the feasibility of engrafting limited numbers of retrovirus-transduced hepatocytes without morbidity and achieving persistent gene expression lasting at least four months after gene therapy. The variable metabolic responses observed following low-level genetic reconstitution in the five patients studied precludes a broader application of liver-directed gene therapy without modifications that consistently effect substantially greater gene transfer.
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