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关键词： Indium phosphide   lidar   photonic integrated circuits   remote sensing   semiconductor lasers   spectroscopy  

摘要： An indium phosphide photonic integrated circuit (PIC) was demonstrated for integrated path differential absorption lidar of atmospheric carbon dioxide (CO2). The PIC consists of two widely tunable sampled grating distributed Bragg reflector (SGDBR) lasers, directional couplers, a phase modulator, a photodiode, and semiconductor optical amplifiers (SOAs). One SGDBR laser, the leader, is locked to the center of an absorption line at 1572.335 nm using the on-chip phase modulator and a bench-top CO2 Herriott reference cell. The other SGDBR laser, the follower, is stepped in frequency over +/- 15 GHz around 1572.335 nm to scan the target CO2 absorption line. The follower laser is offset locked to the leader laser with an optical phase lock loop. An SOA after the follower laser generates a pulse at each frequency step to create a train of pulses that samples the target CO2 absorption line. The PIC components and subsystem are characterized and evaluated based on target performance requirements. The leader laser demonstrated a 236-fold improvement in frequency stability standard deviation when locked compared to free running and the follower laser frequency stability standard deviation compared to the leader laser was 37.6 KHz at a 2 GHz programmed offset.

关键词： Optimal control problems   fractional Volterra integro-differential equations   discrete Hahn polynomials   operational matrix  

摘要： This study develops an efficient numerical method for optimal control problems governed by fractional Volterra integro-differential equations. A new type of polynomials orthogonal with respect to a discrete norm, namely discrete Hahn polynomials, is introduced and its properties investigated. Fractional operational matrices for the orthogonal polynomials are also derived. A direct numerical algorithm supported by the discrete Hahn polynomials and operational matrices is used to approximate solution of optimal control problems governed by fractional Volterra integro-differential equations. Several examples are analyzed and the results compared with those of other methods. The required CPU time assesses the computational cost and complexity of the proposed method.

关键词： Retinal detachment   Cone photoreceptor   Immunohistochemistry   Spectral domain optical coherence tomography  

摘要： Retinal detachment is a vision-threatening condition, which occurs when the neurosensory retina is separated from its blood supply. The main purpose of this study was to examine the effect of experimental retinal detachment in rats on cone photoreceptors. Retinal detachment was induced in the eyes of rats via subretinal injection of sodium hyaluronate. Experimental detachment caused a rapid, sustained loss of short (S)- and medium/long (M/L)-wavelength cone opsins. Importantly, S-opsin(+) cones were affected earlier than M/L-opsin(+) cones and were affected to a greater extent than M/L-opsin(+) cones throughout the duration of detachment. In comparison, to cone opsins, reductions in other cone markers-peanut agglutinin PNA and cone arrestin-were substantially less marked. These data suggest that loss of cone opsins does not reflect cone degeneration and may rather indicate prolonged downregulation of specific proteins in affected cones. This conclusion is supported by the lack of TUNEL+- cone arrestin(+) double-labelled cells at the time point of greatest rod photoreceptor cell death, together with the partial recovery of cone arrestin(+) cell numbers over time. Analysis of retinas that had naturally re-attached reinforced the deduction that few cones die following detachment, but also highlighted that prolonged detachment leads to deconstruction of cone segments that may not be readily reversible. Survival and functional recovery of cones following surgery for retinal detachment is vital for successful recovery of vision. The data suggest that experimental detachment in rats may offer a useful approach to model the response of S-cones to retinal detachment in humans.

关键词： Ivermectin   Moxidectin   Glutamate-gated chloride channels   Homology model   Caenorabditis elegans   Electrophysiology  

摘要： Background and purpose: Nematode glutamate-gated chloride channels (GluCls) are targets of ivermectin (IVM) and moxidectin (MOX), structurally dissimilar macrocyclic lactone (ML) anthelmintics. IVM and MOX possess different pharmacokinetics and efficacy profiles but are thought to have the same binding site, through which they allosterically activate GluCls, apart from the GLC-2 receptor, which is antagonized by IVM. Our goal was to determine GLC-2 sensitivity to MOX, investigate residues involved in antagonism of GLC-2, and to identify differences in receptor-level pharmacology between IVM and MOX. Experimental approach: Two-electrode voltage clamp electrophysiology was used to study the pharmacology of Caenorhabditis elegans GLC-2 receptors heterologously expressed in Xenopus laevis oocytes. In silico homology modeling identified Cel-GLC-2 residues Met291 and Gln292 at the IVM binding site that differ from other GluCls;we mutated these residues to those found in ML-sensitive GluCls, and those of filarial nematode GLC-2. Key results: We discovered that MOX inhibits wild-type C. elegans GLC-2 receptors roughly 10-fold more potently than IVM, and with greater maximal inhibition of glutamate activation (MOX = 86.9 +/- 2.5%;IVM = 57.8 +/- 5.9%). IVM was converted into an agonist in the Met291Gln mutant, but MOX remained an antagonist. Glutamate responses were abrogated in a Met291Leu Gln292Thr double mutant (mimicking filarial nematode GLC-2), but MOX and IVM were converted into positive allosteric modulators of glutamate at this construct. Conclusions and implications: Our data provides new insights into differences in receptor-level pharmacology between IVM and MOX and identify residues responsible for ML antagonism of GLC-2.

关键词： adaptation   balance   gait   margin of stability   perturbation  

摘要： Introducing unexpected perturbations to challenge gait stability is an effective approach to investigate balance control strategies. Little is known about the extent to which people can respond to small perturbations during walking. This study aimed to determine how subjects adapted gait stability to multidirectional perturbations with small magnitudes applied on a stride-by-stride basis. Ten healthy young subjects walked on a treadmill that either briefly decelerated belt speed ("stick"), accelerated belt speed ("slip"), or shifted the platform medial-laterally at right leg mid-stance. We quantified gait stability adaptation in both anterior-posterior and medial-lateral directions using margin of stability and its components, base of support, and extrapolated center of mass. Gait stability was disrupted upon initially experiencing the small perturbations as margin of stability decreased in the stick, slip, and medial shift perturbations and increased in the lateral shift perturbation. Gait stability metrics were generally disrupted more for perturbations in the coincident direction. Subjects employed both feedback and feedforward strategies in response to the small perturbations, but mostly used feedback strategies during adaptation. Subjects primarily used base of support (foot placement) control in the lateral shift perturbation and extrapolated center of mass control in the slip and medial shift perturbations. These findings provide new knowledge about the extent of gait stability adaptation to small magnitude perturbations applied on a stride-by-stride basis and reveal potential new approaches for balance training interventions to target foot placement and center of mass control. NEW & NOTEWORTHY Little is known about if and how humans can adapt to small magnitude perturbations experienced on a stride-by-stride basis during walking. Here, we show that even small perturbations disrupted gait stability and that subjects could still adapt their reactive balance co

关键词： arterial stiffness   electronic hookah   electronic water pipe   hookah smoking   inflammation   oxidation  

摘要： BACKGROUND: Traditional hookah smoking has grown quickly to become a global tobacco epidemic. More recently, electronic hookahs (e-hookahs)-vaped through traditional water pipes-were introduced as healthier alternatives to combustible hookah. With combustible tobacco smoking, oxidative stress, inflammation, and vascular stiffness are key components in the development and progression of atherosclerosis. The comparable effects of hookah are unknown. RESEARCH QUESTION: What is the differential acute effect of e-hookah vaping vs combustible hookah smoking on oxidation, inflammation, and arterial stiffness? STUDY DESIGN AND METHODS: In a randomized crossover design study, among a cohort of 17 healthy young adult chronic hookah smokers, we investigated the effect of e-hookah vaping and hookah smoking on measures of conduit arterial stiffness, including carotid-femoral pulse wave velocity (PWV), augmentation index-corrected for heart rate before and after a 30-min exposure session. We assessed a panel of circulating biomarkers indicative of inflammation and oxidants and measured plasma nicotine and exhaled carbon monoxide (CO) levels before and after the sessions. RESULTS: Hookah vaping tended to lead to a larger acute increase in PWV than hookah smoking (mean +/- SE: e-hookah, +0.74 +/- 0.12 m/s;combustible hookah, +0.57 +/- 0.14 m/s [P < .05 for both] ), indicative of large artery stiffening. Compared with baseline, only e-hookah vaping induced an acute increase in augmentation index (e-hookah, +5.58 +/- 1.54% [P = .004];combustible hookah, +2.87 +/- 2.12% [P = not significant] ). These vascular changes were accompanied by elevation of the proinflammatory biomarkers high-sensitivity C-reactive protein, fibrinogen, and tumor necrosis factor a after vaping (all P < .05). No changes in biomarkers of inflammation and oxidants were observed after smoking. Compared with baseline, exhaled CO levels were higher after smoking than after vaping (+36.81 +/- 6.70 parts per million v

关键词： Algebraic differential equation   Algebraic curve   Place   Formal Puiseux series solution   Convergent solution  

摘要： Given an autonomous first order algebraic ordinary differential equation F(y, y') = 0, we prove that every formal Puiseux series solution of F(y, y') = 0, expanded around any finite point or at infinity, is convergent. The proof is constructive and we provide an algorithm to describe all such Puiseux series solutions. Moreover, we show that for any point in the complex plane there exists a solution of the differential equation which defines an analytic curve passing through this point. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Alcohol misuse   Cannabis use disorder   Young adults   Mobile treatment   Latent growth modeling  

摘要： Alcohol misuse is more prevalent, frequent, and severe among young adults who use cannabis. Treatment of dual alcohol and cannabis users may have mixed results, with some studies reporting that alcohol misuse increases when cannabis use decreases (substance substitution), while others report that alcohol misuse decreases along with decreasing cannabis use (treatment spillover), and others report no association. Additionally, little research tests whether gender differences are found in treatment of dual alcohol and cannabis users, which may be expected given previous alcohol-focused treatments showing larger effects for females. In the current study, we present a secondary analysis of a randomized clinical trial testing a text message-delivered cannabis use disorder (CUD) treatment (peer network counseling text or "PNC-txt"). The trial included 101 young adults ages 18-25 who met criteria for CUD. We tested whether alcohol use and binge drinking frequency (4+/5+ drinks for women/men) decreased in response to the PNC-txt treatment, which has previously shown effectiveness in reducing cannabis use days. Latent growth models tested PNC-txt effects on the monthly rate of change in alcohol use and binge drinking across three months. In the full sample, we found no evidence of significant treatment effects on alcohol use (d = -0.07) or binge drinking (d = -0.10). Moderation analyses, however, indicated the PNC-txt effect on both alcohol use and binge drinking differed significantly by gender. PNC-txt led to significantly larger decreases in alcohol use (d = -0.53) and binge drinking days (d = -0.43) across the three months for females, whereas the study saw opposite (but nonsignificant) effects for males (d = 0.30 and 0.16 for alcohol use and binge drinking, respectively). We found no evidence that reductions in alcohol use and binge drinking were associated with cannabis use decreases, arguing against direct substitution or spillover effects. These results provide eviden