Task-adaptive physical reservoir computing.

Reservoir computing is a neuromorphic architecture that may offer viable solutions to the growing energy costs of machine learning. In software-based machine learning, computing performance can be readily reconfigured to suit different computational tasks by tuning hyperparameters. This critical functionality is missing in 'physical' reservoir computing schemes that exploit nonlinear and history-dependent responses of physical systems for data processing. Here we overcome this issue with a 'task-adaptive' approach to physical reservoir computing. By leveraging a thermodynamical phase space to reconfigure key reservoir properties, we optimize computational performance across a diverse task set. We use the spin-wave spectra of the chiral magnet Cu2OSeO3 that hosts skyrmion, conical and helical magnetic phases, providing on-demand access to different computational reservoir responses. The task-adaptive approach is applicable to a wide variety of physical systems, which we show in other chiral magnets via above (and near) room-temperature demonstrations in Co8.5Zn8.5Mn3 (and FeGe).

Michael Addition-Elimination Ring-Opening Polymerization.

A cyclic thioenone system capable of controlled ring-opening polymerization (ROP) is presented that leverages a reversible Michael addition-elimination (MAE) mechanism. The cyclic thioenone monomers are easy to access and modify and for the first time incorporate the dynamic reversibility of MAE with chain-growth polymerization. This strategy features mild polymerization conditions, tunable functionalities, controlled molecular weights (Mn), and narrow dispersities. The obtained polythioenones exhibit excellent optical transparency and good mechanical properties and can be depolymerized to recover the original monomers. Density functional theory (DFT) calculations of model reactions offer insights into the role of monomer conformation in the polymerization process, as well as explaining divergent reactivity observed in seven-membered thiepane (TP) and eight-membered thiocane (TC) ring systems. Collectively, these findings demonstrate the feasibility of MAE mechanisms in ring-opening polymerization and provide important guidelines toward future monomer designs.

Halide Abstraction-Mediated Synthesis of a Highly Twisted Amide.

Highly strained [3.2.1] bicyclic twisted amide 2 and corresponding amidium 10 were synthesized for the first time through Ag(I)-mediated halide abstraction. After initial lactamization attempts failed, a second-generation strategy was devised to target amidium 10 via intramolecular alkylation. The 3,4-dihydroisoquinolone cyclization precursor was regioselectively prepared via a Rh(III)-catalyzed C-H activation/annulation reaction. After Ag(I)-assisted cyclization, the [3.2.1] bicyclic framework of amidium 10 was confirmed by X-ray crystallography and enabled full solution characterization of twisted amide 2.

Bumble bee diet breadth increases with local abundance and phenophase duration, not intraspecific variation in body size.

Patterns of abundance across space and time, and intraspecific variation in body size, are two species attributes known to influence diet breadth and the structure of interaction networks. Yet, the relative influence of these attributes on diet breadth is often assumed to be equal among taxonomic groups, and the relationship between intraspecific variation in body size on interaction patterns is frequently neglected. We observed bee-flower interactions in multiple locations across Montana, USA, for two growing seasons and measured spatial and temporal patterns of abundance, along with interspecific and intraspecific variation in body size for prevalent species. We predicted that the association between spatial and temporal patterns of abundance and intraspecific variation in body size, and diet breadth, would be stronger for bumble bee compared to non-bumble bee species, because species with flexible diets and long activity periods can interact with more food items. Bumble bees had higher local abundance, occurred in many local communities, more intraspecific variation in body size, and longer phenophases compared to non-bumble bee species, but only local abundance and phenophase duration had a stronger positive association with the diet breadth of bumble bee compared to non-bumble bee species. Communities with a higher proportion of bumble bees also had higher intraspecific variation in body size at the network-level, and network-level intraspecific variation in body size was positively correlated with diet generalization. Our findings highlight that the association between species attributes and diet breadth changes depending on the taxonomic group, with implications for the structure of interaction networks.

Wilderness Medical Society Clinical Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents: 2024 Update.

To provide guidance to the general public, clinicians, and avalanche professionals about best practices, the Wilderness Medical Society convened an expert panel to revise the evidence-based guidelines for the prevention, rescue, and resuscitation of avalanche and nonavalanche snow burial victims. The original panel authored the Wilderness Medical Society Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents in 2017. A second panel was convened to update these guidelines and make recommendations based on quality of supporting evidence.

Chemically Recyclable Polymer System Based on Nucleophilic Aromatic Ring-Opening Polymerization.

The development of chemically recyclable polymers with desirable properties is a long-standing but challenging goal in polymer science. Central to this challenge is the need for reversible chemical reactions that can equilibrate at rapid rates and provide efficient polymerization and depolymerization cycles. Based on the dynamic chemistry of nucleophilic aromatic substitution (SNAr), we report a chemically recyclable polythioether system derived from readily accessible benzothiocane (BT) monomers. This system represents the first example of a well-defined monomer platform capable of chain-growth ring-opening polymerization through an SNAr manifold. The polymerizations reach completion in minutes, and the pendant functionalities are easily customized to tune material properties or render the polymers amenable to further functionalization. The resulting polythioether materials exhibit comparable performance to commercial thermoplastics and can be depolymerized to the original monomers in high yields.

Magnitude of Preoperative C-Reactive Protein Elevation Is Associated With De Novo Crohn's Disease After Ileal Pouch-Anal Anastomosis in Patients With Severe Colitis.

BACKGROUND: Total proctocolectomy with ileal pouch-anal anastomosis has become the standard procedure for patients with medically refractory ulcerative colitis, although a subset will develop de novo Crohn's disease. OBJECTIVE: In this study, we investigated the association of preoperative C-reactive protein levels with the development of de novo Crohn's disease after ileal pouch-anal anastomosis. DESIGN: A prospectively maintained database of patients undergoing ileal pouch-anal anastomosis was reviewed. PATIENTS: Preoperative C-reactive protein levels were compared between patients who developed de novo Crohn's disease and those who did not. De novo Crohn's disease was defined as small-bowel inflammation proximal to the ileal pouch or perianal disease identified more than 3 months after ileostomy closure. To minimize the heterogeneity of the timing of preoperative C-reactive protein measurement and the severity of ulcerative colitis, only hospitalized patients who had proctocolectomy for severe ulcerative colitis were included in the study. MAIN OUTCOME MEASURES: Development of de novo Crohn's disease was analyzed. RESULTS: Of 105 patients, 23 (22%) developed de novo Crohn's disease. Having C-reactive protein in the third tertile significantly increased the risk of developing de novo Crohn's disease (HR 3.44, 95% CI 1.10- 10.70, p = 0.03) compared to in the first tertile. In a multivariable model, a C-reactive protein in the third or second tertile vs the first tertile and younger age was associated with the development of de novo Crohn's disease. LIMITATIONS: Limited to only hospitalized patients with severe ulcerative colitis. CONCLUSIONS: In hospitalized patients undergoing ileal pouch-anal anastomosis for medically refractory ulcerative colitis, higher preoperative C-reactive protein levels appear to increase the risk of developing de novo Crohn's disease. See Video Abstract at http://links.lww.com/DCR/B750.LA MAGNITUD DE LA ELEVACIÓN PREOPERATORIA DE LA PROTEÍNA C REACTIVA SE ASOCIA CON APARICIÓN DE UNA ENFERMEDAD DE CROHN DE NOVO DESPUÉS DE UNA ANASTOMOSIS DE BOLSA ILEAL AL ANO EN PACIENTES CON COLITIS SEVERAANTECEDENTES:La proctocolectomía total con anastomosis bolsa ileal-anal se ha convertido en el procedimiento estándar para los pacientes con colitis ulcerativa refractaria al tratamiento médico, aunque un subgrupo desarrollará una enfermedad de Crohn de novo.OBJETIVO:En este estudio investigamos la asociación de los niveles de proteína C reactiva preoperatoria con el desarrollo de la enfermedad de Crohn de novo, después de la anastomosis bolsa ileal-anal.DISEÑO:Se revisó una base de datos recolectada en forma prospectiva, de pacientes sometidos a anastomosis bolsa ileal-anal.PACIENTES:Se compararon los niveles de proteína C reactiva preoperatoria entre los pacientes que desarrollaron la enfermedad de Crohn de novo y los que no la desarrollaron. La enfermedad de Crohn de novo se definió como una inflamación del intestino delgado proximal a la bolsa ileal o una enfermedad perianal identificada más de 3 meses después del cierre de la ileostomía. Para minimizar la heterogeneidad del momento de la medición de la proteína C reactiva preoperatoria y la gravedad de la colitis ulcerativa, solo se incluyeron en el estudio los pacientes hospitalizados que se sometieron a una proctocolectomía por colitis ulcerativa grave.PRINCIPALES MEDIDAS DE RESULTADO:se analizó el desarrollo de la enfermedad de Crohn de novo.RESULTADOS:De 105 pacientes, 23 (22%) desarrollaron enfermedad de Crohn de novo. Tener una proteína C reactiva en el tercer tercil aumentó significativamente el riesgo de desarrollar la enfermedad de Crohn de novo (HR 3,44, IC del 95%: 1,10-10,70, p = 0,03) en comparación con el primer tercil. En un modelo multivariable, una proteína C reactiva en el tercer o segundo tercil frente al primer tercil y una edad más joven se asoció con el desarrollo de la enfermedad de Crohn de novo.LIMITACIONES:Limitado solo a pacientes hospitalizados con colitis ulcerativa grave.CONCLUSIONES:En pacientes hospitalizados sometidos a anastomosis bolsa ileal-anal por colitis ulcerativa refractaria al tratamiento médico, niveles más elevados de proteína C reactiva preoperatoria parecen aumentar el riesgo de desarrollar enfermedad de Crohn de novo. Consulte Video Resumen en http://links.lww.com/DCR/B750. (Traducción-Eduardo Londoño-Schimmer).

Frequency dependence of the ultrasonic power reflected from the water-tissue interface of human cancellous bone in vitro.

Numerous studies have performed in vitro ultrasonic measurements of cancellous bone in water to develop techniques for ultrasonic bone assessment. Because cancellous bone is a highly porous medium, ultrasonic reflections at the water-bone interface may be frequency dependent. The goal of this study was to investigate the effect of porosity on the frequency dependence of the reflected power. Ultrasonic measurements were performed in a water tank at room temperature on 15 specimens of cancellous bone prepared from the proximal end of 9 human femurs using single element, broadband transducers with center frequencies of 3.5, 5, 7.5, and 10 MHz. Power spectra of pulses reflected from the water-specimen interface were corrected for the frequency response of the measurement system to obtain the reflected power in decibels RdB(f). To suppress random phase cancellation effects, RdB(f) was averaged over multiple sites on multiple specimens. A frequency dependence of RdB(f) was observed in the 2.6-10 MHz range. The frequency dependence was moderate, with a maximum change of less than 6 dB over the entire frequency range. RdB(f) was greatest for low porosity specimens. The frequency averaged intensity reflection coefficient ranged from 7.4 × 10-4 to 7.8 × 10-3 for high and low porosity specimen groups, respectively.

Why the cognitive "fountain of youth" may be upstream: Pathways to dementia risk and resilience through social connectedness.

Research suggests social connectedness may help older adults with dementia maintain cognitive functionality and quality of life. However, little is known about its specific social and biological mechanisms. This paper proposes two pathways through social bridging (i.e., cognitive enrichment through expansive social networks) and bonding (i.e., neuroendocrine benefits of integration in cohesive social networks). We provide preliminary evidence for these pathways using neuroimaging, cognitive, and egocentric social network data from the Social Networks and Alzheimer's Disease (SNAD) study (N = 280). We found that network size, density, and presence of weak ties (i.e., social bridging) moderated the association between brain atrophy and cognitive function, while marriage/cohabitation (i.e., social bonding) moderated the association between perceived stress and cognitive function. We argue that social connectedness may have downstream implications for multiple pathophysiological processes in cognitive aging, even negating existing structural damage to the brain, making it a strong candidate for clinical or policy intervention.

Modulating Twisted Amide Geometry and Reactivity Through Remote Substituent Effects.

The unusual reactivity of twisted amides has long been associated with the degree of amide distortion, though classical bridged bicyclic amides offer limited methods to further modify these parameters. Here, we report that the geometry and reactivity of a single twisted amide scaffold can be significantly modulated through remote substituent effects. Guided by calculated ground state geometries, a library of twisted amide derivatives was efficiently prepared through a divergent synthetic strategy. Kinetic and mechanistic investigations of these amides in the alkylation/halide-rebound ring-opening reaction with alkyl halides show a strong positive correlation between the electron donating ability of the substituent and distortion of the amide bond, leading to rates of nucleophilic substitution spanning nearly 2 orders of magnitude. The rate limiting step of the cascade sequence is found to be dependent on the nature of the substituent, and additional studies highlight the role of solvent polarity and halide ion on reaction pathway and efficiency.

Tuning Supramolecular Polymer Assembly through Stereoelectronic Interactions.

The supramolecular polymerization of 2,11-dithia[3.3]paracyclophanes through self-complementary intermolecular and transannular amide hydrogen bonding is presented. An n → π* interaction between the amide hydrogen bonding units and the central bridging atom results from the single-point exchange of a carbon atom for a sulfur atom. This orbital donor-acceptor interaction can be strengthened by oxidizing the sulfide to a sulfone which acts to shorten the donor···acceptor distance and increase orbital overlap. Experimental signatures of the increased n → π* interaction include larger isodesmic polymerization elongation constants in solution, changes in characteristic bond stretching frequencies, and geometric/structural changes evaluated by X-ray crystallography. The experimental data are supported by extensive computational investigations of both assembling and nonassembling 2,11-dithia[3.3]paracyclophanes as well as a rationally designed model system to confirm the role of stereoelectronic effects on supramolecular polymer assembly.

Gatekeeping Ketosynthases Dictate Initiation of Assembly Line Biosynthesis of Pyrrolic Polyketides.

Assembly line biosynthesis of polyketide natural products involves checkpoints where identities of thiotemplated intermediates are verified before polyketide extension reactions are allowed to proceed. Determining what these checkpoints are and how they operate is critical for reprogramming polyketide assembly lines. Here we demonstrate that ketosynthase (KS) domains can perform this gatekeeping role. By comparing the substrate specificities for polyketide synthases that extend pyrrolyl and halogenated pyrrolyl substrates, we find that KS domains that need to differentiate between these two substrates exercise high selectivity. We additionally find that amino acid residues in the KS active site facilitate this selectivity and that these residues are amenable to rational engineering. On the other hand, KS domains that do not need to make selectivity decisions in their native physiological context are substrate-promiscuous. We also provide evidence that delivery of substrates to polyketide synthases by non-native carrier proteins is accompanied by reduced biosynthetic efficiency.

Synthesis and Characterization of Cationic Dendrimer-PDMS Hybrids.

A modular strategy for the synthesis of dendron-linear polymer hybrids comprised of a flexible polydimethylsiloxane (PDMS) midblock with cationic 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) dendron end groups is developed. The invention of a scalable methodology to access quaternary ammonium carboxylate building blocks and their direct use in esterification chemistry enables rapid access to cationic bis-MPA dendrons. The convergent click coupling of highly charged dendrons to hydrophobic PDMS chain-ends gives a 12-membered family of hybrids that are comprised of different dendron generations (G1-3) and quaternary ammonium alkyl chain lengths (C4 , C8 , C12 , C16 ). This provides a library of materials with variable hydrophobicity, charge density, and chain-end valency. The physical behavior of the dendron-linear PDMS hybrid copolymers significantly changes after introduction of the cationic dendron end-groups and leads to soft-solid materials as a result of inhibited chain mobility. These PDMS-dendron hybrids are expected to behave as surface-active antimicrobial additives in bulk cross-linked silicone systems.

We Post It, U Reddit: Exploring the Potential of Reddit for Health Interventions Targeting College Populations.

Reddit is an anonymous social media platform that allows users to create, modify, share, and discuss content. While this platform is widely used by mainstream audiences, little research exists on how Redditors respond to health information when it appears in general, non-health specific forums called subreddits. Guided by media system dependency theory, the purpose of this study was to anonymously intervene on college subreddits to explore how Redditors interacted with messages about smoke-free policy compliance. Two messages were posted two weeks apart on ten college subreddits, yielding 370 comments (per thread range = 66-0) and 552 Karma points (per thread range = 123-0). A content analytic approach was employed, identifying eight content themes, and classifying message tone. The most popular themes were general smoking [n = 85], animosity toward smoke-free policies/compliance [n = 68], and smoke-free policy/compliance support [n = 65]). Most comments expressed a neutral tone [n = 196]. Data suggest that Redditors are willing to interact with health content on their college subreddits to varying degrees, especially if this content conforms to norms of the subreddit and/or platform. Implications from the findings suggest important considerations for use of Reddit as a future site for health interventions.

Alternating Cascade Metathesis Polymerization of Enynes and Cyclic Enol Ethers with Active Ruthenium Fischer Carbenes.

Ruthenium alkoxymethylidene complexes have rarely been demonstrated as active species in metathesis reactions and are frequently regarded as inert. Herein, we highlight the ability of these Fischer-type carbenes to participate in cascade alternating ring-opening metathesis polymerization through their efficient alkyne addition reactions. When enyne monomers are combined with low-strain cyclic vinyl ethers, a controlled chain-growth copolymerization occurs that exhibits high degrees of alternation (>90% alternating diads) and produces degradable poly(vinyl ether) materials with low dispersities and targetable molecular weights. This new method is amenable to the synthesis of alternating diblock polymers that can be degraded to small-molecule fragments under aqueous acidic conditions. This work furthers the potential of Fischer-type ruthenium alkylidenes in polymerization strategies and presents new avenues for the generation of functional metathesis materials.

Trump Cardiomyopathy: A New Form of Takotsubo Cardiomyopathy.

An 84-year-old man developed angina while watching televised coverage of the President Trump impeachment hearings and presented to the emergency department with positive cardiac biomarkers and EKG changes indicative of ST-elevation myocardial infarction. Echocardiogram and coronary angiography were consistent with non-ischemic, 3 vessel coronary artery disease with apical hypokinesis resulting in the diagnosis of Takotsubo Cardiomyopathy. This case is the first report of politically-induced cardiomyopathy and warrants further evaluation of political stress as an etiology of cardiac events.

Influence of Amide Connectivity on the Hydrogen-Bond-Directed Self-Assembly of [n.n]Paracyclophanes.

Reported here is the synthesis and self-assembly characterization of [n.n]paracyclophanes ([n.n]pCps, n=2, 3) equipped with anilide hydrogen bonding units. These molecules differ from previous self-assembling [n.n]paracyclophanes ([n.n]pCps) in the connectivity of their amide hydrogen bonding units (C-centered/carboxamide vs. N-centered/anilide). This subtle change results in a ≈30-fold increase in the elongation constant for the [2.2]pCp-4,7,12,15-tetraanilide ([2.2]pCpNTA) compared to previously reported [2.2]pCp-4,7,12,15-tetracarboxamide ([2.2]pCpTA), and a ≈300-fold increase in the elongation constant for the [3.3]pCp-5,8,14,17-tetraanilide ([3.3]pCpNTA) compared to previously reported [3.3]pCp-5,8,14,17-tetracarboxamide ([3.3]pCpTA). The [n.n]pCpNTA monomers also represent the reversal of a previously reported trend in solution-phase assembly strength when comparing [2.2]pCpTA and [3.3]pCpTA monomers. The origins of the assembly differences are geometric changes in the association between [n.n]pCpNTA monomers-revealed by computations and X-ray crystallography-resulting in a more favorable slipped stacking of the intermolecular π-surfaces ([n.n]pCpNTA vs. [n.n]pCpTA), and a more complementary H-bonding geometry ([3.3]pCpNTA vs. [2.2]pCpNTA).

Cultural Competency Interventions During Medical School: a Scoping Review and Narrative Synthesis.

Many medical accreditation bodies agree that medical students should be trained to care for diverse patient populations. However, the teaching methods that medical schools employ to accomplish this goal vary widely. The purpose of this work is to summarize current cultural competency teaching for medical students and their evaluation methods. A scoping review was completed by searching the databases PubMed, Scopus, MedEdPORTAL, and MEDLINE for the search terms "medical education" and "cultural competency" or "cultural competence." Results were summarized using a narrative synthesis technique. One hundred fifty-four articles on cultural competency interventions for medical students were systematically identified from the literature and categorized by teaching methods, length of intervention, and content. Fifty-six articles had a general focus, and ninety-eight articles were focused on specific populations including race/ethnicity, global health, socioeconomic status, language, immigration status, disability, spirituality at the end of life, rurality, and lesbian, gay, bisexual, transgender, and queer. About 54% of interventions used lectures as a teaching modality, 45% of the interventions described were mandatory, and 9.7% of interventions were not formally evaluated. The authors advocate for expansion and more rigorous analysis of teaching methods, teaching philosophies, and outcome evaluations with randomized controlled trials that compare the relative effectiveness of general and population-specific cultural competency interventions.

Self-Assembling [n.n]Paracyclophanes: A Structure-Property Relationship Study.

Reported here is the synthesis, characterization, and isodesmic supramolecular polymerization of [3.3]paracyclophane-5,8,14,17-tetracarboxamide ([3.3]pCpTA). The self-assembling monomer, a bridge-expanded homolog of [2.2]paracyclophane-4,7,12,15-tetracarboxamide ([2.2]pCpTA), forms homochiral assemblies in nonpolar solution and the solid state through double-helical intermolecular and transannular hydrogen bonding. The additional methylene unit in the [3.3]paracyclophane bridge results in a weakened supramolecular assembly for [3.3]pCpTA compared to [2.2]pCpTA in solution. Likely origins of the change in assembly strength, revealed through X-ray crystallography, computational analysis, and solution-phase spectroscopy, are an increase in (a) the intramolecular and intermolecular deck-to-deck spacing compared to [2.2]paracyclophane resulting from larger amide dihedral angles accompanying transannular hydrogen bonding in the [3.3]paracyclophane and (b) monomer entropy associated with the scissoring motion of the [3.3]paracyclophane bridge.

Emergency valve-in-valve transcatheter aortic valve implantation for endocarditis degeneration.

The use of transcatheter aortic valve implantation (TAVI) in the emergency setting has not been widely reported, and TAVI is generally contraindicated in the context of endocarditis. Here we describe a patient developing acute cardiogenic shock due to prosthetic aortic valve degeneration with free-flow aortic regurgitation 8 months after receiving treatment for confirmed infective endocarditis. Due to his clinical status, he was deemed unfit for redo surgery, and he underwent salvage valve-in-valve (ViV)-TAVI. The patient made an excellent recovery. Postprocedure he was treated with a 6-week course of antibiotics, and at 18-months follow-up remains very well with no evidence of reinfection. This case may demonstrate that for selected patients with degenerative prosthetic aortic valve disease, despite a history of infective endocarditis, ViV-TAVI may be considered an alternative to redo surgery in the emergency setting.