Finite element analysis of kangaroo astragali: A new angle on the ankle.

Using finite element analysis on the astragali of five macropodine kangaroos (extant and extinct hoppers) and three sthenurine kangaroos (extinct proposed bipedal striders) we investigate how the stresses experienced by the ankle in similarly sized kangaroos of different hypothesized/known locomotor strategy compare under different simulation scenarios, intended to represent the moment of midstance at different gaits. These tests showed a clear difference between the performance of sthenurines and macropodines with the former group experiencing lower stress in simulated bipedal strides in all species compared with hopping simulations, supporting the hypothesis that sthenurines may have utilized this gait. The Pleistocene macropodine Protemnodon also performed differently from all other species studied, showing high stresses in all simulations except for bounding. This may support the hypothesis of Protemnodon being a quadrupedal bounder.

Restless legs syndrome is prevalent in adults with cystic fibrosis and impacts sleep quality.

BACKGROUND: Restless legs syndrome (RLS) is a sensorimotor disorder that is prevalent in chronic inflammatory conditions. RLS prevalence, risk factors, and impact on sleep in CF have not been extensively characterized to date. METHODS: An initial cohort was examined, including 75 persons with CF (PwCF) and 75 control subjects, to look at the prevalence and severity of RLS. A second validation cohort of 191 PwCF was then enrolled from two CF centers to examine risk factors for RLS. A diagnosis of RLS was made according to the International RLS Study Group (IRLSSG) criteria. Sleep quality was identified using the Pittsburgh sleep quality index (PSQI). Epworth sleepiness scale (ESS) was used to measure daytime sleepiness. We then analyzed laboratory and clinical risk factors and sleep symptoms for potential risk factors for RLS. RESULTS: In the initial cohort, 36 % of PwCF had RLS, and 9 % of these had significant RLS. In contrast, only 15 % of controls had RLS, and none had significant RLS. In the second larger validation cohort with 191 subjects, a comparable prevalence of RLS was identified. Higher hemoglobin A1c, use of SSRI/SNRI medications, worse PSQI and ESS sleep quality scores, lower lung function, and higher antibiotic usage were significantly associated with a diagnosis of RLS. By multivariate multinominal logistic regression analysis, higher HbA1c and worse PSQI global sleep quality scores were independent predictors of significant RLS. CONCLUSIONS: RLS is highly prevalent in CF. Higher HbA1c and poor sleep quality, signified by higher PSQI, were each independent predictors of RLS.

Optogenetic Stimulation of Single Ganglion Cells in the Living Primate Fovea.

Though the responses of the rich variety of retinal ganglion cells (RGCs) reflect the totality of visual processing in the retina and provide the sole conduit for those processed responses to the brain, we have much to learn about how the brain uses these signals to guide behavior. An impediment to developing a comprehensive understanding of the role of retinal circuits in behavior is the paucity of causal studies in the intact primate visual system. Here we demonstrate the ability to optogenetically activate individual RGCs with flashes of light focused on single RGC somas in vivo , without activation of neighboring cells. The ability to selectively activate specific cells is the first step toward causal experiments that directly link retinal circuits to visual experience and behavior.

Effects of Secondary Dopant Anions on Emissivity and Related Properties of Poly(3,4-ethylenedioxythiophene).

Smart materials that are energy efficient and take up less space are crucial in the development of new technologies. Electrochromic polymers (ECPs) are one such class of materials that actively change their optical behavior in both visible and infrared parts of the electromagnetic spectrum. They show promise in a wide range of applications, from active camouflage to smart displays/windows. The full capabilities of ECPs are still yet to be explored, for while their electrochromic properties are well established, their Infrared (IR) modulation is less reported on. This study addresses the potential of ECPs in active IR modulating devices by optimization of Vapor Phase Polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via the substitution of its dopant anion. Dynamic ranges denoting emissivity changes between reduced and oxidized states of PEDOT are found across dopants of tosylate, bromide, sulfate, chloride, perchlorate, and nitrate. Relative to the emissivity of reduced (neutral) PEDOT, a range of ±15% is achieved from the doped PEDOT films, and a maximum dynamic range of 0.11 across a 34% change is recorded for PEDOT doped with perchlorate.

Optogenetic therapy restores retinal activity in primate for at least a year following photoreceptor ablation.

All retina-based vision restoration approaches rely on the assumption that photoreceptor loss does not preclude reactivation of the remaining retinal architecture. Whether extended periods of vision loss limit the efficacy of restorative therapies at the retinal level is unknown. We examined long-term changes in optogenetic responsivity of foveal retinal ganglion cells (RGCs) in non-human primates following localized photoreceptor ablation by high-intensity laser exposure. By performing fluorescence adaptive optics scanning light ophthalmoscopy (AOSLO) of RGCs expressing both the calcium indicator GCaMP6s and the optogenetic actuator ChrimsonR, it was possible to track optogenetic-mediated calcium responses in deafferented RGCs over time. Fluorescence fundus photography revealed a 40% reduction in ChrimsonR fluorescence from RGCs lacking photoreceptor input over the 3 weeks following photoreceptor ablation. Despite this, in vivo imaging revealed good cellular preservation of RGCs 3 months after the loss of photoreceptor input, and histology confirmed good structural preservation at 2 years. Optogenetic responses of RGCs in primate persisted for at least 1 year after the loss of photoreceptor input, with a sensitivity index similar to optogenetic responses recorded in intact retina. These results are promising for all potential therapeutic approaches to vision restoration that rely on preservation and reactivation of RGCs.

Iatrogenic Delayed Pneumothorax After Transbronchial Biopsy.

Transbronchial biopsy (TBB) is one of the commonly performed procedures by pulmonologists in everyday practice. Although the procedure has a very low-risk profile, complications often develop in certain patients. Pneumothorax is one such complication pertaining to TBB. As only a small percent of procedures get complicated by pneumothorax, handful of cases have been reported with its delayed occurrence in the past 5 decades. The purpose of our report is to highlight another uncommon yet interesting case of delayed iatrogenic pneumothorax in an immunocompromised patient after TBB. Although the chain of events behind the pathophysiology of delayed pneumothorax largely remain a mystery, its development has been linked to altered immune mechanics as they are frequently recognized in immunocompromised patients.

Procalcitonin predicts the severity of cystic fibrosis pulmonary exacerbations and readmissions in adult patients: a prospective cohort study.

Patients with cystic fibrosis (CF) experience multiple pulmonary exacerbations throughout their lifetime, resulting in repeated antibiotic exposure and hospital admissions. Reliable diagnostic markers to guide antibiotic treatment in patients with CF, however, are lacking. Given that the CF airway is characterized by persistent and frequent bacterial infection, our goal was to determine if procalcitonin (PCT) could be used as a severity and prognostic marker of CF exacerbation. We enrolled 40 participants at the time of diagnosis of CF pulmonary exacerbation. Inclusion criteria: age ≥19 years with exacerbation requiring antibiotics as determined by the treating physician. Exclusion criteria: antibiotics initiated more than 48 hours prior to enrollment, and pregnancy. Blood samples were collected on enrollment day and after 7-10 days of treatment. Of the 40 patients enrolled, 23 (57.5%) had detectable levels of PCT (≥0.05 ng/mL). PCT levels were significantly associated with pulmonary exacerbation scores (p=0.01) and per cent decrease in forced expiratory volume in 1 second (FEV1) (p=0.01) compared with the best in the last 12 months. Those who had worsening PCT during treatment had less improvement in FEV1 (p=0.001) and were more likely to be readmitted to the hospital sooner (p<0.0001). Likewise, those who had a detectable PCT at the time of admission were more likely to be readmitted sooner (p=0.03). PCT elevation during antibiotic treatment is associated with less improvement in FEV1 and earlier readmission. A detectable PCT level occurs only in more severe CF exacerbations. Multicenter trials are needed to confirm whether PCT may play a role in the clinical care of patients with CF.

Recurrent Pneumothorax with CPAP Therapy for Obstructive Sleep Apnea.

Pulmonary barotrauma such as pneumothorax (PTX) is a known complication of invasive mechanical ventilation. However, it is uncommonly reported with the use of noninvasive positive pressure ventilation (NPPV) and CPAP (continuous positive airway pressure) therapy. We present a case of a 66-year-old female who presented with chronic dyspnea on exertion secondary to right-sided diaphragmatic hernia. The patient also underwent a home sleep study which suggested obstructive sleep apnea (OSA) for which she was initiated on CPAP. She then underwent surgical repair of her right diaphragmatic hernia. The patient developed pneumothorax three times over the course of the following several months, once on the right side and twice on the left side. The patient's incidences of PTX had a temporal association with the CPAP initiation. Her CPAP therapy was discontinued permanently after the third occurrence of PTX. With this case report, we highlight the risk of barotrauma with the use of CPAP for OSA. There are very few reported cases of PTX in association with NPPV therapy for OSA. The lung-protective ventilation strategies and limiting the positive airway pressures can help reduce the risk of pulmonary barotrauma with CPAP.

Influence of Postsynthesis Heat Treatment on Vapor-Phase-Polymerized Conductive Polymers.

The effect of thermal treatment on the structure and electrical/optical properties of vapor phase-polymerized poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos) and polypyrrole:tosylate (PPy:Tos) polymer films was investigated. Thermal treatment was applied postpolymerization but prior to washing the embedded oxidant layer out of the polymer film. Structural and chemical changes arising from the treatment were studied in the context of their conductive and electrochromic behavior. Spectroscopic analysis indicated a rise in the doping levels of both conductive polymers when exposed to thermal treatment. Additionally, an increase in the film thickness was recorded after the oxidant and other unbound species were removed from the polymer layer using an ethanol rinse. As such, a strong indication that polymerization continued even in the absence of (external) monomer vapor was present. This film thickness increase was most pronounced for PPy:Tos but also present in the PEDOT:Tos film. Heat-treated films exhibited enhanced cohesion, making them more robust and therefore increasing the viability for the material to be used in the optoelectronics area. This robustness, due to additional (cross-linking) oligomer growth, came at the expense of lower conductivity relative to their untreated counterparts.

Differential Effects of Climate on Survival Rates Drive Hybrid Zone Movement.

Climate change has been implicated as driving shifts of hybridizing species' range limits [1, 2]. Whether and how much hybrid zones move depends on the relative fitness of hybridzing species under changing conditions [3, 4]. However, fitness is rarely linked to both climatic conditions and movement of hybrid zones, such that the relationship between climate change and hybrid zone dynamics remains tenuous [5]. Here we report how interactions between climate (seasonal precipitation) and competitor densities result in steep differentials in survival, which in turn drive hybrid zone movement for two woodrat species (Neotoma fuscipes and N. macrotis) in central California, USA. Using 6 years of capture-mark-recapture data, we found that the smaller-bodied species, N. macrotis, and hybrids had survival advantages over the larger-bodied N. fuscipes in the contact region during dry winters and wet springs. This pattern of differential survival, with N. macrotis having a consistent advantage over N. fuscipes during our study period, matched the spatial dynamics of the hybrid zone, which moved steadily north into N. fuscipes territory, with its estimated center moving ∼150 m north in 6 years. Our findings provide a unique demonstration of range movements emerging from a complex interplay between climate and competition. Although all study site areas experienced the same climatic conditions, competitive effects created a complex spatial pattern of survival differentials, which in turn influenced hybrid zone movement. Characterization of fitness differentials derived from replicated demographic studies of contact regions between competitors should greatly improve our ability to understand and forecast climate-driven range dynamics.

Pseudomonas Quinolone Signal Induces Oxidative Stress and Inhibits Heme Oxygenase-1 Expression in Lung Epithelial Cells.

Pseudomonasaeruginosa causes lung infections in patients with cystic fibrosis (CF). The Pseudomonas quinolone signal (PQS) compound is a secreted P. aeruginosa virulence factor that contributes to the pathogenicity of P. aeruginosa We were able to detect PQS in sputum samples from CF patients infected with P. aeruginosa but not in samples from uninfected patients. We then tested the hypothesis that PQS induces oxidative stress in host cells by determining the ability of PQS to induce the production of reactive oxygen species (ROS) in lung epithelial cells (A549 and primary normal human bronchial epithelial [NHBE]) cells and macrophages (J774A.1 and THP-1). ROS production induced by PQS was detected with fluorescent probes (dichlorodihydrofluorescein diacetate, dihydroethidium, and MitoSOX Red) in conjunction with confocal microscopy and flow cytometry. PQS induced ROS production in lung epithelial (A549 and NHBE) cells and macrophages (J774A.1 and THP-1 cells). NHBE cells were sensitive to PQS concentrations as low as 500 ng/ml. PQS significantly induced early apoptosis (P < 0.05, n = 6) in lung epithelial cells, as measured by annexin/propidium iodide detection by flow cytometry. However, no change in apoptosis upon PQS treatment was seen in J774A.1 cells. Heme oxygenase-1 (HO-1) protein is an antioxidant enzyme usually induced by oxidative stress. Interestingly, incubation with PQS significantly reduced HO-1 and NrF2 expression in A549 and NHBE cells but increased HO-1 expression in J774A.1 cells (P < 0.05, n = 3), as determined by immunoblotting and densitometry. These PQS effects on host cells could play an important role in the pathogenicity of P. aeruginosa infections.

Enteral tube feeding for individuals with cystic fibrosis: Cystic Fibrosis Foundation evidence-informed guidelines.

Nutrition is integral to the care of individuals with cystic fibrosis (CF). Better nutritional status is associated with improved pulmonary function. In some individuals with CF, enteral tube feeding can be useful in achieving optimal nutritional status. Current nutrition guidelines do not include detailed recommendations for enteral tube feeding. The Cystic Fibrosis Foundation convened an expert panel to develop enteral tube feeding recommendations based on a systematic review of the evidence and expert opinion. These guidelines address when to consider enteral tube feeding, assessment of confounding causes of poor nutrition in CF, preparation of the patient for placement of the enteral feeding tube, management of the tube after placement and education about enteral feeding. These recommendations are intended to guide the CF care team, individuals with CF, and their families through the enteral tube feeding process.

Decoupling the effects of confinement and passivation on semiconductor quantum dots.

Semiconductor (SC) quantum dots (QDs) have recently been fabricated by both chemical and plasma techniques for specific absorption and emission of light. Their optical properties are governed by the size of the QD and the chemistry of any passivation at their surface. Here, we decouple the effects of confinement and passivation by utilising DC magnetron sputtering to fabricate SC QDs in a perfluorinated polyether oil. Very high band gaps are observed for fluorinated QDs with increasing levels of quantum confinement (from 4.2 to 4.6 eV for Si, and 2.5 to 3 eV for Ge), with a shift down to 3.4 eV for Si when oxygen is introduced to the passivation layer. In contrast, the fluorinated Si QDs display a constant UV photoluminescence (3.8 eV) irrespective of size. This ability to tune the size and passivation independently opens a new opportunity to extending the use of simple semiconductor QDs.

Hydrophilic Organic Electrodes on Flexible Hydrogels.

Prompted by the rapidly developing field of wearable electronics, research into biocompatible substrates and coatings is intensifying. Acrylate-based hydrogel polymers have gained widespread use as biocompatible articles in applications such as contact and intraocular lenses. Surface treatments and/or coatings present one strategy to further enhance the performance of these hydrogels or even realize novel functionality. In this study, the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is deposited from the vapor phase onto hydrated hydrogel substrates and blended with biocompatibilizing coconstituents incorporating polyethylene glycol (PEG) and polydimethyl siloxane (PDMS) moieties. Plasma pretreatment of the dehydrated hydrogel substrate modifies its surface topography and chemical composition to facilitate the attachment of conductive PEDOT-based surface layers. Manipulating the vapor phase polymerization process and constituent composition, the PEDOT-based coating is engineered to be both hydrophilic (i.e. to promote biocompatibility) and highly conductive. The fabrication of this conductively coated hydrogel has implications for the future of wearable electronic devices.

Unusual Nature of Fingerprints and the Implications for Easy-to-Clean Coatings.

Irrespective of the technology, we now rely on touch to interact with devices such as smart phones, tablet computers, and control panels. As a result, touch screen technologies are frequently in contact with body grease. Hence, surface deposition arises from localized inhomogeneous finger-derived contaminants adhering to a surface, impairing the visual/optical experience of the user. In this study, we examined the contamination itself in order to understand its static and dynamic behavior with respect to deposition and cleaning. A process for standardized deposition of fingerprints was developed. Artificial sebum was used in this process to enable reproducibility for quantitative analysis. Fingerprint contamination was shown to be hygroscopic and to possess temperature- and shear-dependent properties. These results have implications for the design of easily cleanable surfaces.

Parasite prevalence and community diversity in sympatric and allopatric populations of two woodrat species (Sigmodontinae: Neotoma) in central California.

Patterns of host-parasite association may vary across the landscape in part because of host and parasite diversity, divergence, local ecology, or interactions among these factors. In central coastal California, we quantified parasite prevalence, infection intensity, and diversity in two sister species of woodrats (Neotoma fuscipes and Neotoma macrotis) where the species co-occur (sympatry) and where each species exists alone (allopatry). In feces from 50 adults we identified seven taxa: the protozoans Eimeria, Giardia, and Cryptosporidium, the nematodes Trichuris, Aspicularis, and Eucoleus, and a cestode in the family Anoplocephalidae. Gastrointestinal parasite infection intensity and diversity were higher in males than in females, a difference that was most pronounced in the more aggressive N. fuscipes. Both species had lower infection intensity in sympatry than in allopatry and in sympatry the two species did not differ in infection intensity in total but did maintain distinct parasite communities. Taken together, our findings suggest that host evolutionary differences, including perhaps species-specific patterns of aggressive behavior, as well as local ecology, influence the likelihood of infection by these endoparasite taxa.

A solid-state nuclear magnetic resonance study of post-plasma reactions in organosilicone microwave plasma-enhanced chemical vapor deposition (PECVD) coatings.

Plasma-polymerized organosilicone coatings can be used to impart abrasion resistance and barrier properties to plastic substrates such as polycarbonate. Coating rates suitable for industrial-scale deposition, up to 100 nm/s, can be achieved through the use of microwave plasma-enhanced chemical vapor deposition (PECVD), with optimal process vapors such as tetramethyldisiloxane (TMDSO) and oxygen. However, it has been found that under certain deposition conditions, such coatings are subject to post-plasma changes; crazing or cracking can occur anytime from days to months after deposition. To understand the cause of the crazing and its dependence on processing plasma parameters, the effects of post-plasma reactions on the chemical bonding structure of coatings deposited with varying TMDSO-to-O2 ratios was studied with (29)Si and (13)C solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) using both single-pulse and cross-polarization techniques. The coatings showed complex chemical compositions significantly altered from the parent monomer. (29)Si MAS NMR spectra revealed four main groups of resonance lines, which correspond to four siloxane moieties (i.e., mono (M), di (D), tri (T), and quaternary (Q)) and how they are bound to oxygen. Quantitative measurements showed that the ratio of TMDSO to oxygen could shift the chemical structure of the coating from 39% to 55% in Q-type bonds and from 28% to 16% for D-type bonds. Post-plasma reactions were found to produce changes in relative intensities of (29)Si resonance lines. The NMR data were complemented by Fourier transform infrared (FTIR) spectroscopy. Together, these techniques have shown that the bonding environment of Si is drastically altered by varying the TMDSO-to-O2 ratio during PECVD, and that post-plasma reactions increase the cross-link density of the silicon-oxygen network. It appears that Si-H and Si-OH chemical groups are the most susceptible to post-plasma reactions. Coatings produced at a low TMDSO-to-oxygen ratio had little to no singly substituted moieties, displayed a highly cross-linked structure, and showed less post-plasma reactions. However, these chemically more stable coatings are less compatible mechanically with plastic substrates, because of their high stiffness.

Direct imaging of mechanical and chemical gradients across the thickness of graded organosilicone microwave PECVD coatings.

The characterization of variations in the chemical composition and ensuing mechanical properties across the thickness of coatings with continuously varying compositions through their thickness (graded coatings) presents considerable challenges for current analytical techniques in materials science. We report here the direct imaging of nanomechanical and chemical gradients across cross-sections of an organosilicone coating fabricated via microwave plasma enhanced chemical vapor deposition (PECVD). Cross-sectional nanoindentation was used to determine the mechanical properties of uniform and graded organosilicone coatings. Both hardness and modulus across the coatings were directly measured. Additionally, "modulus mapping" on cross-sections was used to map the complex modulus. For the graded coating, it was found that variations in the complex modulus was predominantly due to varying storage modulus. It was observed that at the interface with the substrate there was a low storage modulus, which linearly increased to a relatively high storage modulus at the surface. It is proposed that the increase in stiffness, from the substrate interface to the outer surface, is due to the increasing content of a cross-linked O-Si-O network. This mechanical gradient has been linked to a change in the Si:O ratio via direct compositional mapping using ToF-SIMS. Direct mapping of the mechanical and compositional gradients across these protective coatings provides insight into the changes in properties with depth and supports optimization of the critical mechanical performance of PECVD graded coatings.

Condensation and freezing of droplets on superhydrophobic surfaces.

Superhydrophobic coatings are reported as promising candidates for anti-icing applications. Various studies have shown that as well as having ultra water repellency the surfaces have reduced ice adhesion and can delay water freezing. However, the structure or texture (roughness) of the superhydrophobic surface is subject to degradation during the thermocycling or wetting process. This degradation can impair the superhydrophobicity and the icephobicity of those coatings. In this review, a brief overview of the process of droplet freezing on superhydrophobic coatings is presented with respect to their potential in anti-icing applications. To support this discussion, new data is presented about the condensation of water onto physically decorated substrates, and the associated freezing process which impacts on the freezing of macroscopic droplets on the surface.

Semi-metallic polymers.

Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being suitable for thermoelectric applications. We measure the thermoelectric properties of various poly(3,4-ethylenedioxythiophene) samples, and observe a marked increase in the Seebeck coefficient when the electrical conductivity is enhanced through molecular organization. This initiates the transition from a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics.