Controlled Diels-Alder "Click" Strategy to Access Mechanically Aligned Main-Chain Liquid Crystal Networks.

Aligned liquid crystal polymers are materials of interest for electronic, optic, biological and soft robotic applications. The manufacturing and processing of these materials have been widely explored with mechanical alignment establishing itself as a preferred method due to its ease of use and widespread applicability. However, the fundamental chemistry behind the required two-step polymerization for mechanical alignment has limitations in both fabrication and substrate compatibility. In this work we introduce a new protection-deprotection approach utilizing a two-stage Diels-Alder cyclopentadiene-maleimide step-growth polymerization to enable mild yet efficient, fast, controlled, reproducible and user-friendly polymerizations, broadening the scope of liquid crystal systems. Thorough characterization of the films by DSC, DMA, POM and WAXD show the successful synthesis of a uniaxially aligned liquid crystal network with thermomechanical actuation abilities.

Controlling Dark Equilibria and Enhancing Donor-Acceptor Stenhouse Adduct Photoswitching Properties through Carbon Acid Design.

A novel library of tunable negative photochromic compounds, donor-acceptor Stenhouse adducts (DASAs), is reported. Tailoring the electron deficient "acceptor" moiety yielded DASAs that can be activated with mild visible and far red light. The effect of acceptor composition on reactivity, absorption, equilibrium, and cyclability is exploited for the design of high performance photoswitches. The structural changes to the carbon acid acceptor also provide access to new, more structurally diverse DASA derivatives by facilitating the ring-opening reaction with electron deficient amine donors.

QCM-D Investigation of Swelling Behavior of Layer-by-Layer Thin Films upon Exposure to Monovalent Ions.

Polyelectrolyte multilayers and layer-by-layer assemblies are susceptible to structural changes in response to ionic environment. By altering the salt type and ionic strength, structural changes can be induced by disruption of intrinsically bound ion pairs within the multilayer network via electrostatic screening. Notably, high salt concentrations have been used for the purposes of salt-annealing and self-healing of LbL assemblies with KBr, in particular, yielding a remarkably rapid response. However, to date, the structural and swelling effects of various monovalent ion species on the behavior of LbL assemblies remain unclear, including a quantitative view of ion content in the LbL assembly and thickness changes over a wide concentration window. Here, we investigate the effects of various concentrations of KBr (0 to 1.6 M) on the swelling and de-swelling of LbL assemblies formed from poly(diallyldimethylammonium) polycation (PDADMA) and poly(styrene sulfonate) polyanion (PSS) in 0.5 M NaCl using quartz-crystal microbalance with dissipation (QCM-D) monitoring as compared to KCl, NaBr, and NaCl. The ion content after salt exchange is quantified using neutron activation analysis (NAA). Our results demonstrate that Br- ions have a much greater effect on the structure of as-prepared thin films than Cl- at ionic strengths above assembly conditions, which is possibly caused by the more chaotropic nature of Br-. It is also found that the anion in general dominates the swelling response as compared to the cation because of the excess PDADMA in the multilayer. Four response regimes are identified that delineate swelling due to electrostatic repulsion, slight contraction, swelling due to doping, and film destruction as ionic strength increases. This understanding is critical if such materials are to be used in applications requiring submersion in chemically dynamic environments such as sensors, coatings on biomedical implants, and filtration membranes.

Individuals, traditions, and the righteous.

Whitehouse's article posits several plausible hypotheses, but suffers from an unwarranted reliance on the importance of distinct social groups in the causation of self-sacrificing behavior. A focus on relationships between individual kin is better able to account for both the evolution of self-sacrifice and present forms of self-sacrifice. The practical importance of this point is discussed.

Post-surgical outcome and prognostic factors in canine malignant melanomas of the haired skin: 87 cases (2003-2015).

The medical records of 87 dogs treated with surgery for cutaneous malignant melanoma (CMM) of the haired skin were retrospectively reviewed for overall survival time (OST), progression-free survival time (PFS), and prognostic factors. The post-surgery median PFS and median OST were 1282 days and 1363 days, respectively. The post-surgery metastatic rate was 21.8% with a local recurrence rate of 8%. Increasing mitotic index (MI) was predictive of a significantly decreased OST and PFS on multivariable analysis [hazard ratio (HR): 1.05, 95% confidence interval (CI): 1.02 to 1.07 and HR: 1.04, 95% CI: 1.02 to 1.06, respectively]. Increasing age was likewise predictive of a significantly decreased OST and PFS on multivariable analysis (HR: 1.39, 95% CI: 1.17 to 1.65 and HR: 1.33, 95% CI: 1.14 to 1.54, respectively). These results confirm clinical impressions that long survival times are likely in dogs diagnosed with malignant melanoma of the haired skin when treated with surgery alone.

Résultat post-chirurgical et facteurs de pronostic pour les mélanomes malins canins de la peau poilue : 87 cas (2003­2015). Les dossiers médicaux de 87 chiens traités à l'aide d'une chirurgie pour le mélanome malin cutané (MMC) de la peau poilue ont été évalués rétrospectivement pour le temps de survie global (TSG), le temps de survie sans progression (TSSP) et les facteurs de pronostic. Le TSSP médian après la chirurgie et le TSG médian étaient de 1282 jours et de 1363 jours, respectivement. Le taux métastasique après la chirurgie était de 21,8 % avec un taux de récurrence local de 8 %. L'augmentation de l'indice mitotique (IM) était prédictive d'un TSG et d'un TSSP réduits à l'analyse multivariable (ratio de risque [RR] : 1,05, intervalle de confiance [IC] de 95 % : 1,02 à 1,07 et RR : 1,04, IC de 95 % : 1,02 à 1,06, respectivement). La progression de l'âge était aussi prédictive d'une réduction importante du TSG et du TSSP à l'analyse multivariable (RR : 1,39, IC de 95 % : 1,17 à 1,65 et RR : 1,33, IC de 95 % : 1,14 à 1,54, respectivement). Ces résultats confirment les impressions cliniques que des longs délais de survie sont probables chez les chiens diagnostiqués avec le mélanome malin de la peau poilue lorsqu'ils sont uniquement traités à l'aide d'une chirurgie.(Traduit par Isabelle Vallières).

Vesicopreputial anastomosis for the treatment of obstructive urolithiasis in goats.

OBJECTIVE: To describe a novel surgical technique for the correction of recurrent obstructive urolithiasis in male goats. STUDY DESIGN: Clinical case series. ANIMALS: Castrated male goats (n = 4). METHODS: Medical records of male goats having undergone vesicopreputial anastomosis (VPA) as a treatment for obstructive urolithiasis were reviewed for history, signalment, clinical signs, and intraoperative and postoperative complications. Long-term follow-up (≥12 months) was obtained by telephone interview with owners or by clinical examination. RESULTS: All goats had undergone at least one surgical procedure (median, 2.5, range 2-4) to correct obstructive urolithiasis before undergoing VPA. Postoperative complications included premature removal of the tube from the bladder (1 goat), bacterial cystitis (2), and abscess formation (1). One goat suffered stricture of the anastomosis site 3 months following the original procedure and underwent a second VPA and 1 goat died 7 months after surgery due to severe, acute hydronephrosis and renal failure. Long-term survival ≥12 months was good with 3/4 goats (75%) or 3/5 VPA procedures (60%) having unobstructed urine flow at 12 months. CONCLUSION: Vesicopreputial anastomosis is a feasible surgical procedure for the correction of recurrent obstructive urolithiasis in male goats and one that can result in a favorable clinical outcome. Further investigation in a larger population of goats is warranted for the evaluation of the suitability of VPA in male goats with obstructive urolithiasis.

Tunable Visible and Near Infrared Photoswitches.

A class of tunable visible and near-infrared donor-acceptor Stenhouse adduct (DASA) photoswitches were efficiently synthesized in two to four steps from commercially available starting materials with minimal purification. Using either Meldrum's or barbituric acid "acceptors" in combination with aniline-based "donors", an absorption range spanning from 450 to 750 nm is obtained. Additionally, photoisomerization results in complete decoloration for all adducts, yielding fully transparent, colorless solutions and films. Detailed investigations using density functional theory, nuclear magnetic resonance, and visible absorption spectroscopies provide valuable insight into the unique structure-property relationships for this novel class of photoswitches. As a final demonstration, selective photochromism is accomplished in a variety of solvents and polymer matrices, a significant advantage for applications of this new generation of DASAs.

Comparison of 3 methods of onychectomy.

The frequency of claw regrowth, bony remnants, and complications in cats that underwent forelimb onychectomy using laser, scalpel, or guillotine techniques were evaluated. Eighty-seven client-owned cats were recruited from 27 veterinary clinics in the Canadian Atlantic provinces. At least 1 year after onychectomy the cats underwent a physical examination, gait analysis, and radiographic evaluation by 1 of 2 authors. There was no significant difference in the frequency of claw regrowth among the 3 methods (P = 0.283). Significantly more cats had bony remnants following guillotine onychectomy (P < 0.001). Bony remnants were significantly associated with claw regrowth (P = 0.001). Cats that underwent laser onychectomy had significantly less post-operative complications (P = 0.023). The long-term outcome was not significantly different among the 3 methods. We conclude that leaving remnants of the third phalanx in situ is associated with an increased frequency of claw regrowth. Laser onychectomy may be preferred to reduce the risk of post-operative complications, bony remnants, and claw regrowth.

Comparaison de 3 méthodes d'onychectomie. La fréquence de la repousse des griffes, des reliquats osseux et des complications chez les chats qui avaient subi une onychectomie des pattes avant en utilisant le laser, le scalpel, ou les techniques de guillotine a été évaluée. Quatre-vingt-sept chats appartenant à des clients ont été recrutés dans 27 cliniques vétérinaires des provinces de l'Atlantique du Canada. Au moins 1 an après l'onychectomie, les chats ont subi une évaluation physique, une analyse de la démarche et une évaluation radiographique par 1 des 2 auteurs. Il n'y avait pas de différence significative dans la fréquence de la repousse des griffes entre les 3 méthodes (P = 0,283). Un nombre significativement supérieur de chats avaient des reliquats osseux après l'onychectomie à la guillotine (P < 0,001). Les reliquats osseux étaient significativement associés à la repousse de griffes (P = 0,001). Les chats qui ont subi une onychectomie au laser présentaient un nombre significativement inférieur de complications postopératoires (P = 0,023). Les résultats à long terme n'étaient pas significativement différents entre les 3 méthodes. Nous avons conclu que la présence de reliquats in situ dans la troisième phalange est associée à une fréquence accrue de repousse des griffes. L'onychectomie au laser peut être préférable pour réduire le risque de complications postopératoires, des reliquats et de la repousse des griffes.(Traduit par Isabelle Vallières).

Sialolipoma of a minor salivary gland in a dog.

A 10-year-old golden retriever dog was presented for evaluation of progressive panting, inspiratory stridor, and gagging. Oropharyngeal examination revealed a soft, nonulcerated, pedunculated mass arising from the right tonsillar fossa. The mass was completely excised and histopathology was consistent with a sialolipoma. No regrowth of the mass was evident 6 months after surgery.

Lipome salivaire d'une glande salivaire mineure chez un chien. Un chien Golden retriever âgé de 10 ans a été présenté pour l'évaluation d'un halètement progressif, d'un stridor respiratoire et des haut-le-cœur. Un examen oropharyngien a révélé une petite masse molle non ulcérée et pédonculée se dressant sur la fosse de l'amygdale droite. La masse a été entièrement excisée et l'histopathologie était conforme à un lipome salivaire. Six mois après la chirurgie, aucune repousse de la masse n'a été constatée.(Traduit par Isabelle Vallières).

Design of Surface-Aligned Main-Chain Liquid-Crystal Networks Prepared under Ambient, Light-Free Conditions Using the Diels-Alder Cycloaddition.

Surface-aligned liquid-crystal networks (LCNs) offer a solution for developing functional materials capable of performing a range of tasks, including actuation, shape memory, and surfaces patterning. Here we show that Diels-Alder cycloaddition can be used to prepare the backbone of planar aligned LCNs under mild ambient conditions without the addition of additives or UV irradiation. The mechanical properties of the networks have robust viscoelastic modulus and stiffness with a reversible local free volume change upon physical aging. This study shows new opportunities to design surface-aligned LCNs based on additive free step-growth Diels-Alder polymerization and enables the potential to incorporate a wider range of photochromic materials into LCNs.

Freshwater unionid mussels threatened by predation of Round Goby (Neogobius melanostomus).

Indigenous freshwater mussels (Unionidae) are integral to riverine ecosystems, playing a pivotal role in aquatic food webs and providing ecological services. With populations on the decline worldwide, freshwater mussels are of conservation concern. In this study, we explore the propensity of the invasive Round Goby (Neogobius melanostomus) fish to prey upon indigenous freshwater mussels. First, we conducted lab experiments where Round Gobies were given the opportunity to feed on juvenile unionid mussels and macroinvertebrates, revealing rates and preferences of consumption. Several Round Gobies consumed whole freshwater mussels during these experiments, as confirmed by mussel counts and x-ray images of the fishes. Next, we investigated Round Gobies collected from stream habitats of the French Creek watershed, which is renowned for its unique and rich aquatic biodiversity. We developed a novel DNA metabarcoding method to identify the specific species of mussels consumed by Round Goby and provide a new database of DNA gene sequences for 25 indigenous unionid mussel species. Several of the fishes sampled had consumed indigenous mussels, including the Elktoe (non-endangered), Creeper (non-endangered), Long Solid (state endangered), and Rayed Bean (federally endangered) species. The invasive Round Goby poses a growing threat to unionid mussels, including species of conservation concern. The introduction of the invasive Round Goby to freshwaters of North America is shaping ecosystem transitions within the aquatic critical zone having widespread implications for conservation and management.

Nuclear mechanosensing drives chromatin remodelling in persistently activated fibroblasts.

Fibrotic disease is caused by the continuous deposition of extracellular matrix by persistently activated fibroblasts (also known as myofibroblasts), even after the resolution of the injury. Using fibroblasts from porcine aortic valves cultured on hydrogels that can be softened via exposure to ultraviolet light, here we show that increased extracellular stiffness activates the fibroblasts, and that cumulative tension on the nuclear membrane and increases in the activity of histone deacetylases transform transiently activated fibroblasts into myofibroblasts displaying condensed chromatin with genome-wide alterations. The condensed structure of the myofibroblasts is associated with cytoskeletal stability, as indicated by the inhibition of chromatin condensation and myofibroblast persistence after detachment of the nucleus from the cytoskeleton via the displacement of endogenous nesprins from the nuclear envelope. We also show that the chromatin structure of myofibroblasts from patients with aortic valve stenosis is more condensed than that of myofibroblasts from healthy donors. Our findings suggest that nuclear mechanosensing drives distinct chromatin signatures in persistently activated fibroblasts.

Reversible Actuation via Photoisomerization-Induced Melting of a Semicrystalline Poly(Azobenzene).

Photoisomerization of azobenzene in polymer matrices is a powerful method to convert photon energy into mechanical work. While most previous studies have focused on incorporating azobenzene within amorphous or liquid crystalline materials, the limited extents of molecular ordering and correspondingly modest enthalpy changes upon switching in such systems has limited the achievable energy densities. In this work, we introduce a semicrystalline main-chain poly(azobenzene), where photoisomerization is capable of reversibly triggering melting and recrystallization under essentially isothermal conditions. These materials can be drawn into aligned fibers, yielding optically driven two-way shape memory actuators capable of reversible bending.

Diagnostic utility of the Active Compression Test for the superior labrum anterior posterior tear: A systematic review.

BACKGROUND: The Active Compression Test has been proposed to have high diagnostic accuracy for superior labrum anterior to posterior tears. The aim of this systematic review was to compile the available evidence for this test and evaluate its diagnostic accuracy. METHODS: The databases PubMed, Embase, Cochrane, CINAHL, and SCOPUS were searched for case control, diagnostic studies that evaluated the Active Compression Test between 1999 (date of test introduction) and February 2018. Two independent review authors screened the search results, assessed the risk of bias using QUADAS-2, and extracted the data. RESULTS: Eighteen studies (pooled sample = 3091) were included in this review. Twelve out of 18 studies either had high or unclear risk of bias (66.6%). Results from the pooled analysis of all 18 studies provided that the Active Compression Test is more sensitive (71.5: 95% CI = 68.8, 74.0) than specific (51.9: 95% CI = 50.7, 53.1) and only marginally influenced posttest probability from a pretest probability of 31.7-40.72% with a positive finding and a pretest probability of 31.7-20.33% with a negative finding. DISCUSSION: The Active Compression Test has both limited screening and confirmation ability; therefore, we do not advocate for its use in clinical decision making.

Abnormal Locus Coeruleus Sleep Activity Alters Sleep Signatures of Memory Consolidation and Impairs Place Cell Stability and Spatial Memory.

Sleep is critical for proper memory consolidation. The locus coeruleus (LC) releases norepinephrine throughout the brain except when the LC falls silent throughout rapid eye movement (REM) sleep and prior to each non-REM (NREM) sleep spindle. We hypothesize that these transient LC silences allow the synaptic plasticity that is necessary to incorporate new information into pre-existing memory circuits. We found that spontaneous LC activity within sleep spindles triggers a decrease in spindle power. By optogenetically stimulating norepinephrine-containing LC neurons at 2 Hz during sleep, we reduced sleep spindle occurrence, as well as NREM delta power and REM theta power, without causing arousals or changing sleep amounts. Stimulating the LC during sleep following a hippocampus-dependent food location learning task interfered with consolidation of newly learned locations and reconsolidation of previous locations, disrupting next-day place cell activity. The LC stimulation-induced reduction in NREM sleep spindles, delta, and REM theta and reduced ripple-spindle coupling all correlated with decreased hippocampus-dependent performance on the task. Thus, periods of LC silence during sleep following learning are essential for normal spindle generation, delta and theta power, and consolidation of spatial memories.

Home Healthcare and the Medicare Fraud Strike Force.

Modern federal healthcare fraud investigations use big data to find outliers among providers who are then targeted for enforcement actions. This approach is being used to pursue an outsized number of criminal cases against home healthcare agencies, resulting in decades-long prison sentences and tens of millions in fines. But it is remarkably transparent, giving home healthcare providers ample opportunity to stay out of harm's way. The government has provided the statistical characteristics by which it searches for fraud among home healthcare agencies, along with the benchmarks it uses to determine who is an outlier. And enforcement actions against home healthcare agencies have consistently targeted the same conduct: payments to payment recruiters and physicians in return for referring patients who often do not need the services billed. This article provides practical advice on how home healthcare agencies can gauge and limit their own legal exposure by monitoring their statistics against the government's benchmarks and by instituting basic controls to prevent targeted conduct.

Evaluation of a novel accelerometer for kinetic gait analysis in dogs.

The objective of this study was to evaluate a novel accelerometer-based sensor system, the Walkabout Portable Gait Monitor (WPGM), for use in kinetic gait analysis of dogs. The accelerometer was compared to the common reference standard of force platform analysis. Fifteen client-owned, orthopedically sound dogs of various breeds underwent simultaneous force platform and accelerometer gait trials to measure peak vertical forces (PVFs). The agreement between PVF for the accelerometer and force platform was measured using concordance correlation coefficient (CCC) and was found, overall, to be moderate [CCC = 0.51; 95% confidence interval (CI): 0.46 to 0.56]. The agreement between PVF for the accelerometer and force platform for the forelimbs was positive and substantial (CCC = 0.79; 95% CI: 0.74 to 0.84) and for the hind limbs was positive and low (CCC = 0.34; 95% CI: 0.29 to 0.38). As measured by the accelerometer, PVF was systematically higher than as measured by the force platform (forelimbs 55.3 N, hind limbs 144.3 N). It was also found that, when positioned over the lumbar spine, the WPGM cannot measure PVF of the individual forelimbs and hind limbs, which limits its use as a clinical tool to measure kinetic variables in dogs.

L'objectif de la présente étude était d'évaluer un nouveau système d'accéléromètre, le Walkabout Portable Gait Monitor (WPGM), pour utilisation dans l'analyse de la cinétique de l'allure chez des chiens. L'accéléromètre fut comparé au standard de référence habituel qu'est l'analyse par plaque de force. Quinze chiens de races variées appartenant à des clients, et sans évidence d'atteinte orthopédique ont été soumis de manière simultanée à un test de plaque de force et une étude de la cinétique de l'allure afin de mesurer les forces verticales maximales (PVF). L'accord entre la PVF pour l'accéléromètre et la plaque de force fut mesuré en utilisant le coefficient de corrélation de concordance (CCC) et fut trouvé, de manière globale, à être modéré [CCC = 0,51 %; intervalle de confiance (CI) 95 % : 0,46 à 0,56]. L'accord entre la PVF pour l'accéléromètre et la plaque de force pour les membres antérieurs était positif et élevé (CCC = 0,79; 95 % CI : 0,74 à 0,84) et pour les membres postérieurs était positif et faible (CCC = 0,34; 95 % CI : 0,29 à 0,38). Tel que mesuré par l'accéléromètre, la PVF était systématiquement supérieure à celle mesurée par la plaque de force (membres antérieurs 55,3 N, membres postérieurs 144,3 N). Il fut également trouvé que, lorsque positionné par-dessus la colonne lombaire, le WPGM ne peut mesuré la PVF des membres antérieurs pris individuellement et des membres postérieurs, ce qui limite son utilisation comme outil clinique pour mesurer des variables cinétiques chez les chiens.(Traduit par Docteur Serge Messier).