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Energy absorption capability is critical in biological and engineering materials, particularly when subjected to extreme compressive and impact loading. The cellular structure is recognized for its effectiveness in energy absorption, dissipating energy through material plasticity and structural collapsing, leading to significant densification. In the current work, we demonstrate how natural biological materials, like horns and hooves, control crack generation and propagation through lamellar and tubular structural designs. Interestingly, these natural materials achieve substantial energy absorption without creating large void volumes, relying on generating microcracks and interfaces. Inspired by these biological tissues, lamellar and tubular structures were fabricated via multi-material polymer 3D printing techniques. The resulting bioinspired structures exhibit an impressive energy absorption density of ~18.75 kJ•kg-1, comparable to the performance of metal foams and bioinspired honeycomb structures. Introducing soft-hard interfaces in lamellar and tubules notably enhances impact energy absorption by approximately 167% compared to solid structures printed with a single material. The bioinspired structures maintain structural integrity even under high strain rate impacts of around 2000 s-1, showcasing resistance to deformation and catastrophic failure. This bioinspired approach allows for a combined energy absorption capability in quasi-static compression and high strain-rate impact scenarios.
We present 84 spectra of Type Ib/c and Type IIb supernovae (SNe), describing the individual SNe in detail. The relative depths of the helium absorption lines in the spectra of the SNe Ib appear to provide a measurement of the temporal evolution of the SN, with He I 5876 and He I 7065 growing in strength relative to He I 6678 over time. Light curves for three of the SNe Ib provide a sequence for correlating the helium-line strengths. We find that some SNe Ic show evidence for weak helium absorption, but most do not. Aside from the presence or absence of the helium lines, there are other spectroscopic differences between SNe Ib and SNe Ic. On average, the O I 7774 line is stronger in SNe Ic than in SNe Ib. In addition, the SNe Ic have distinctly broader emission lines at late times, indicating either a consistently larger explosion energy and/or lower envelope mass for SNe Ic than for SNe Ib. While SNe Ib appear to be basically homogeneous, the SNe Ic are quite heterogeneous in their spectroscopic characteristics. Three SNe Ic that may have been associated with gamma-ray bursts are also discussed; two of these have clearly peculiar spectra, while the third seems fairly typical.
Cytotoxic T lymphocytes (CTL) can recognize antigenic peptides bound in a groove formed by the alpha 1 and alpha 2 domains of the heterodimeric major histocompatibility complex class I molecule. Proper assembly, transport, and stability of functional class I molecules is thought to require beta 2 microglobulin (beta 2m), the light chain of the class I heterodimer. We show here that the requirement for beta 2m is not absolute. beta 2m- cells can be stained by the Db alpha 1 domain-specific B22-249.1 monoclonal antibody, which detects a conformation-dependent epitope. Furthermore, beta 2m- Con A blast target cells can be lysed by alloreactive CTL, even in serum-free conditions. Contrary to previous reports, the expression of low levels of conformed Db heavy (H) chains is a property to both normal and transformed beta 2m- cells. Finally, we present evidence that a subset of properly conformed H chains, free of beta 2m, may have almost equal representation on beta 2m+ and beta 2m- cells.
Abstract Objective Building on the original taxonomy of hospital‐based health systems from 20 years ago, we develop a new taxonomy to inform emerging public policy and practice developments. Data Sources The 2016 American Hospital Association's (AHA) Annual Survey; the 2016 IQVIA Healthcare Organizations and Systems (HCOS) database; and the 2017‐2018 National Survey of Healthcare Organizations and Systems (NSHOS). Study Design Cluster analysis of the 2016 AHA Annual Survey data to derive measures of differentiation, centralization, and integration to create categories or types of hospital‐based health systems. Data Collection Principal components factor analysis with varimax rotation generating the factors used in the cluster algorithms. Principal Findings Among the four cluster types, 54% (N = 202) of systems are decentralized (−0.35) and relatively less differentiated (−0.37); 23% of systems (N = 85) are highly differentiated (1.28) but relatively decentralized (−0.29); 15% (N = 57) are highly centralized (2.04) and highly differentiated (0.65); and approximately 9 percent (N = 33) are least differentiated (−1.35) and most decentralized (−0.64). Despite differences in calculation, the Highly Centralized, Highly Differentiated System Cluster and the Undifferentiated, Decentralized System Cluster were similar to those identified 20 years ago. The other two system clusters contained similarities as well as differences from those 20 years ago. Overall, 82 percent of the systems remain relatively decentralized suggesting they operate largely as holding companies allowing autonomy to individual hospitals operating within the system. Conclusions The new taxonomy of hospital‐based health systems bears similarities as well as differences from 20 years ago. Important applications of the taxonomy for addressing current challenges facing the healthcare system, such as the transition to value‐based payment models, continued consolidation, and the growing importance of the social determinants of health, are highlighted.
Reduced sleep duration is associated with HOMA-IR in adolescence. Long sleep duration is not associated. Interventions to extend sleep duration may reduce diabetes risk in youth.
Abstract Hydrosilierungsreaktionen repräsentieren eine wichtige Klasse von chemischen Umwandlungen, und somit besteht ein erhebliches Interesse, den Umfang dieser Reaktionen durch die Entwicklung neuer Katalysatoren zu erweitern. Ein Hauptanliegen, das aus diesen Untersuchungen erwächst, ist die Entwicklung von Katalysatoren mit elektrophilem Charakter, die mittels Si‐H‐Aktivierung die Elektrophilie auf Silicium übertragen. Dieser Mechanismustyp wurde für Katalysatoren vorgeschlagen, die sich von den Übergangsmetallen der 4. Gruppe bis hin zu Hauptgruppenelementverbindungen der 15. Gruppe erstrecken. Zudem sind andere elektrophile Siliciumspezies wie Silylenkomplexe und η 3 ‐H 2 SiRR′‐Komplexe als Intermediate in Hydrosilierungsreaktionen identifiziert worden. In diesem Aufsatz werden unterschiedliche Typen von Katalysatoren verglichen, um die enorme Breite an Hydrosilierungsmechanismen aufzuzeigen, die über elektrophile Siliciumzentren verlaufen. Die Bedeutung dieser Katalysatoren für die Entwicklung neuer Hydrosilierungsreaktionen wird diskutiert.
Mapping sidewalks in urban environments is key in the creation of pedestrian-friendly, sustainable cities. Currently, urban planners are hindered by a lack of information available in a format suitable for the large-scale analysis of sidewalk design. To demonstrate the impact that information technology could have in this area, we leverage techniques from machine learning and computer vision to gather information about the presence and quality of sidewalks in map images. In particular, we identify sidewalk segments in street view images using a random forest classifier, utilizing a set of local and global features that include geometric context, presence of lanes, pixel color, and location. Our results illustrate that this approach is effective in classifying sidewalk segments in a large set of street view images. This algorithm can be easily extended to other datasets, and can be automated to gather complete, fine-grained details about sidewalks for arbitrarily large urban environments.
We present a computational framework for stereopsis based on the outputs of linear spatial filters tuned to a range of orientations and scales. This approach goes beyond edge-based and area-based approaches by using a richer image description and incorporating several stereo cues that previously have been neglected in the computer vision literature. A technique based on using the pseudo-inverse is presented for characterizing the information present in a vector of filter responses. We show how in our framework viewing geometry can be recovered to determine the locations of epipolar lines. An assumption that visible surfaces in the scene are piecewise smooth leads to differential treatment of image regions corresponding to binocularly visible surfaces, surface boundaries, and occluded regions that are only monocularly visible. The constraints imposed by viewing geometry and piecewise smoothness are incorporated into an iterative algorithm that gives good results on random-dot stereograms, artificially generated scenes, and natural grey-level images.
Abstract Unter Verwendung von Phasen‐Transfer‐Katalysatoren wie Tetrabutyl‐ammoniumchlorid oder Adogen 464 werden nucleophile Substitutionsreaktionen an polymeren funktionellen Verbindungen diskutiert.
