Search

Abstract Total internal reflection (TIR) governs the guiding mechanisms of almost all dielectric waveguides and therefore constrains most of the light in the material with the highest refractive index. The few options available to access the properties of lower-index materials include designs that are either lossy, periodic, exhibit limited optical bandwidth or are restricted to subwavelength modal volumes. Here, we propose and demonstrate a guiding mechanism that leverages symmetry in multilayer dielectric waveguides as well as evanescent fields to strongly confine light in low-index materials. The proposed waveguide structures exhibit unusual light properties, such as uniform field distribution with a non-Gaussian spatial profile and scale invariance of the optical mode. This guiding mechanism is general and can be further extended to various optical structures, employed for different polarizations, and in different spectral regions. Therefore, our results can have huge implications for integrated photonics and related technologies.

Abstract Mid-infrared (mid-IR) sensors consisting of silicon nitride (SiN) waveguides were designed and tested to detect volatile organic compounds (VOCs). SiN thin films, prepared by low-pressure chemical vapor deposition (LPCVD), have a broad mid-IR transparent region and a lower refractive index (nSiN = 2.0) than conventional materials such as Si (nSi = 3.4), which leads to a stronger evanescent wave and therefore higher sensitivity, as confirmed by a finite-difference eigenmode (FDE) calculation. Further, in-situ monitoring of three VOCs (acetone, ethanol, and isoprene) was experimentally demonstrated through characteristic absorption measurements at wavelengths λ = 3.0–3.6 μm. The SiN waveguide showed a five-fold sensitivity improvement over the Si waveguide due to its stronger evanescent field. To our knowledge, this is the first time SiN waveguides are used to perform on-chip mid-IR spectral measurements for VOC detection. Thus, the developed waveguide sensor has the potential to be used as a compact device module capable of monitoring multiple gaseous analytes for health, agricultural and environmental applications.

Abstract Background Ticks are important vectors of many pathogens that have contributed to the morbidity and mortality of humans and domestic animals worldwide. Wildlife species have also been implicated as reservoir hosts of a variety of tick-borne pathogens. The objective of this study was to determine which tick-transmitted pathogens were present in the animals harvested from the forest in Trinidad for human consumption. Methods Thin blood smears from 43 neotropical animals were examined microscopically for tick-borne pathogens. Additionally, DNA extraction and PCR amplification of the 16S rRNA gene were used for amplification of Anaplasma and Ehrlichia while the gltA gene was used for Bartonella, and Rickettsia spp. and the 18S rRNA gene for Babesia, Hepatozoon and Theileria species. Results Pathogen DNA was amplified from four samples (a deer, collared peccary and two agoutis). Sequencing of the amplified products from the deer and collared peccary revealed 99.8% homology to Anaplasma bovis and 98.8% homology to Ehrlichia canis, respectively. Sequences from two agoutis revealed 90.4% homology to Theileria spp. DNA of Hepatozoon spp., Bartonella spp. Babesia spp. and Rickettsia spp. was not detected in any of the screened samples. An incidental finding in this study was the presence of bacteria in the blood of animals. Conclusions The results indicate that the DNA of tick-transmitted pathogens is present at a frequency of about 10% in the study population and suggests that neotropical mammals may serve as a source for the potential transmission of tick-borne pathogens to domestic animals and humans. In addition, physicians and hunters should be aware of the symptoms associated with zoonotic tick-borne pathogens so that these infections can be recognised, diagnosed and treated promptly. Bacteria present in carcasses can pose a food safety hazard and hunters should be trained in proper harvesting and handling of carcasses. Graphical Abstract

Rodents and bats are the most diverse mammal group that host Bartonella species. In the Americas, they were described as harboring Bartonella species; however, they were mostly characterized to the genotypic level. We describe here Bartonella isolates obtained from blood samples of one rodent (Peromyscus yucatanicus from San José Pibtuch, Yucatan) and two bat species (Desmodus rotundus from Progreso, and Pteronotus parnellii from Chamela-Cuitzmala) from Mexico. We sequenced and described the genomic features of three Bartonella strains and performed phylogenomic and pangenome analyses to decipher their phylogenetic relationships. The mouse-associated genome was closely related to Bartonella vinsonii. The two bat-associated genomes clustered into a single distinct clade in between lineages 3 and 4, suggesting to be an ancestor of the rodent-associated Bartonella clade (lineage 4). These three genomes showed Bartonella genome, and therefore should be considered as novel species. In addition, our analyses suggest that the B. vinsonii complex should be revised, and all B. vinsonii subspecies need to be renamed and considered as full species. The phylogenomic clustering of the bat-associated Bartonella strains and their virulence factor profile (lack of the Vbh/TraG conjugation system remains of the T4SS) suggest that it should be considered as a new lineage clade (L5) within the Bartonella genus.

Working in a fast-paced environment can lead to shallow breathing, which can exacerbate stress and anxiety. To address this issue, this study aimed to develop micro-interventions that can promote deep breathing in the presence of stressors. First, we examined two types of breathing guides to help individuals learn deep breathing: providing their breathing rate as a biofeedback signal, and providing a pacing signal to which they can synchronize their breathing. Second, we examined the extent to which these two breathing guides can be integrated into a casual game, to increase enjoyment and skill transfer. We used a 2 × 2 factorial design, with breathing guide (biofeedback vs. pacing) and gaming (game vs. no game) as independent factors. This led to four experimental groups: biofeedback alone, biofeedback integrated into a game, pacing alone, and pacing integrated into a game. In a first experiment, we evaluated the four experimental treatments in a laboratory setting, where 30 healthy participants completed a stressful task before and after performing one of the four treatments (or a control condition) while wearing a chest strap that measured their breathing rate. Two-way ANOVA of breathing rates, with treatment (5 groups) and time (pre-test, post-test) as independent factors shows a significant effect for time [F(4, 50) = 18.49, p < 0.001, ηtime2=0.27] and treatment [F(4, 50) = 2.54, p = 0.05, η2 = 0.17], but no interaction effects. Post-hoc t-tests between pre and post-test breathing rates shows statistical significance for the game with biofeedback group [t(5) = 5.94, p = 0.001, d = 2.68], but not for the other four groups, indicating that only game with biofeedback led to skill transfer at post-test. Further, two-way ANOVA of self-reported enjoyment scores on the four experimental treatments, with breathing guide and game as independent factors, found a main effect for game [F(1,20)=24.49,p

Induced pluripotent stem cells (iPSCs) suppress the aggregation of Huntington’s disease (HD) polyQ-expanded huntingtin (HTT). Here the authors show that proteasome activity determines the levels of mutant HTT in HD-iPSCs and find that UBR5 is a modulator of super-vigilant proteostasis of iPSCs.

In 2014, 8.5% of people worldwide over the age of 18 had type 2 diabetes mellitus. It is estimated that, in recent years, the prevalence of this disease has increased mainly in low- and middle-income countries. Health behaviors are considered fundamental in the prevention, treatment, and control of this disease. The aim of this study was to determine if there is an association between health behaviors and satisfaction with family functioning in patients diagnosed with type 2 diabetes mellitus. This is an observational, transversal, analytical study. In the Family Medicine Unit No.33 in Chihuahua, Mexico, 297 patients with a diagnosis of type 2 diabetes mellitus were identified. Data was collected regarding sex, age and the Instrument for Measuring Lifestyles in Diabetics (IMEVID, for its acronym in Spanish) and the Family APGAR. We found that of the total number of patients, 91.6% presented some degree of unfavorable health behaviors, while 92.6% presented some type of family dysfunction. The categorical analysis positively correlated good family functionality with favorable health behaviors, Fisher's exact test p [Med-Science 2017; 6(4.000): 659-662]

En el presente trabajo se exponen las principales características de la herramienta para formulación de raciones por mínimo costo para cerdos, denominada RAC-1. Esta herramienta fue desarrollada con la planilla de cálculos Microsoft Excel, que resuelve problemas de programación lineal con el subprograma Solver

Pluripotent stem cells are thought to require a highly active proteostatic machinery. Here, the authors show that CCT8, a subunit of the proteostatic chaperonin complex, is increased in pluripotent stem cells, and that overexpression of CCT8 in worms increases cellular proteostasis and organismal longevity.

It is unclear whether corrective feedback (CF) provided by L2 computer-assisted pronunciation training (CAPT) tools must be 100% accurate to promote an acceptable level of improvement in pronunciation. Using a web-based interface, 30 native speakers of Chinese completed a pretest, a computer-based training session to produce nine sound contrasts in English, and a posttest. The study manipulated feedback accuracy using a modified "Wizard of Oz" protocol in which a phonetically-trained human listener in a separate room provided CF on the trainees' productions, but the trainees thought that the computer-based system provided the CF. The computer system presented a set of three sound contrasts with 100% accuracy, three with 66% accuracy (with one of three human responses changed randomly), and three with 33% accuracy (with two of three human feedback responses being changed). The trainees' pre- and posttest productions were rated for accuracy by native speakers of English. For trained items, productions were not significantly different when the trainees received CF with 100% or 66% accuracy, but both resulted in greater improvement than feedback with 33% accuracy. An important implication for L2 pronunciation training software is that machine feedback can be beneficial even when it is 'good enough' (i.e., not 100% accurate).

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Several unobtrusive sensors have been tested in studies to capture physiological reactions to stress in workplace settings. Lab studies tend to focus on assessing sensors during a specific computer task, while in situ studies tend to offer a generalized view of sensors’ efficacy for workplace stress monitoring, without discriminating different tasks. Given the variation in workplace computer activities, this study investigates the efficacy of unobtrusive sensors for stress measurement across a variety of tasks. We present a comparison of five physiological measurements obtained in a lab experiment, where participants completed six different computer tasks, while we measured their stress levels using a chest-band (ECG, respiration), a wristband (PPG and EDA), and an emerging thermal imaging method (perinasal perspiration). We found that thermal imaging can detect increased stress for most participants across all tasks, while wrist and chest sensors were less generalizable across tasks and participants. We summarize the costs and benefits of each sensor stream, and show how some computer use scenarios present usability and reliability challenges for stress monitoring with certain physiological sensors. We provide recommendations for researchers and system builders for measuring stress with physiological sensors during workplace computer use.

Los principales y más revolucionarios avances de la biología en este siglo se han derivado de la información proveniente de genomas completos de diferentes organismos. Los descubrimientos que se derivan de la genómica están generando un nuevo paradigma en la biología, sustituyendo la era de la biología centrada en los genes por aquella centrada en los genomas. Este nuevo concepto es base para desarrollos de gran potencial e impacto social en diferentes áreas como la medicina, la agricultura y la industria. El éxito en el desarrollo de métodos de última generación para la secuenciación de genomas, la proteómica y todas las “omicas”, ha contribuido al surgimiento de nuevas posibilidades para el análisis de la enorme cantidad de datos que se están generando mediante el uso de herramientas computacionales, dando origen a una nueva rama de estudio conocida como bioinformática o biología computacional. Este trabajo hace una revisión general del desarrollo de la bioinformática y la biología computacional en Colombia. Inicialmente, a modo de comparación, describimos el desarrollo de esta ciencia en otros países latinoamericanos que son reconocidos en el área. Finalmente, se discuten los principales aspectos que van a jugar un papel importante en el futuro de esta ciencia en nuestro país, y que además justifican la necesidad de crear un centro nacional de bioinformática y biología computacional.

Huntington’s disease (HD) is a fatal neurodegenerative disorder characterized by motor dysfunction, cognitive deficits and psychosis. HD is caused by mutations in the Huntingtin (HTT) gene, resulting in the expansion of polyglutamine (polyQ) repeats in the HTT protein. Mutant HTT is prone to aggregation, and the accumulation of polyQ-expanded fibrils as well as intermediate oligomers formed during the aggregation process contribute to neurodegeneration. Distinct protein homeostasis (proteostasis) nodes such as chaperone-mediated folding and proteolytic systems regulate the aggregation and degradation of HTT. Moreover, polyQ-expanded HTT fibrils and oligomers can lead to a global collapse in neuronal proteostasis, a process that contributes to neurodegeneration. The ability to maintain proteostasis of HTT declines during the aging process. Conversely, mechanisms that preserve proteostasis delay the onset of HD. Here we will review the link between proteostasis, aging and HD-related changes.