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1,589 result(s) for "Vargas, Fernando"
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Shading Ratio Impact on Photovoltaic Modules and Correlation with Shading Patterns
This paper presents the study of a simplified approach to model and analyze the performance of partially shaded photovoltaic modules using the shading ratio. This approach integrates the characteristics of shaded area and shadow opacity into the photovoltaic cell model. The studied methodology is intended to improve the description of shaded photovoltaic systems by specifying an experimental procedure to quantify the shadow impact. Furthermore, with the help of image processing, the analysis of the shading ratio provides a set of rules useful for predicting the current–voltage behavior and the maximum power points of shaded photovoltaic modules. This correlation of the shading ratio and shading patterns can contribute to the supervision of actual photovoltaic installations. The experimental results validate the proposed approach in monocrystalline and polycrystalline technologies of solar panels.
Designing arbitrary single-axis rotations robust against perpendicular time-dependent noise
Low-frequency time-dependent noise is one of the main obstacles on the road toward a fully scalable quantum computer. The majority of solid-state qubit platforms, from superconducting circuits to spins in semiconductors, are greatly affected by 1/ f noise. Among the different control techniques used to counteract noise effects on the system, dynamical decoupling sequences are one of the most effective. However, most dynamical decoupling sequences require unbounded and instantaneous pulses, which are unphysical and can only implement identity operations. Among methods that do restrict to bounded control fields, there remains a need for protocols that implement arbitrary gates with lab-ready control fields. In this work, we introduce a protocol to design bounded and continuous control fields that implement arbitrary single-axis rotations while shielding the system from low-frequency time-dependent noise perpendicular to the control axis. We show the versatility of our method by presenting a set of non-negative-only control pulses that are immediately applicable to quantum systems with constrained control, such as singlet-triplet spin qubits. Finally, we demonstrate the robustness of our control pulses against classical 1/ f noise and noise modeled with a random quantum bath, showing that our pulses can even outperform ideal dynamical decoupling sequences.
Encapsulation improves viability and stability of spray-dried Lactococcus lactis A12 for inclusion in fish feed
During probiotics manufacturing, drying is a crucial process for stabilization of probiotics after fermentation, since drying condition could affect viability and functionality as well as physical properties such as moisture content and water activity, which play key role in stability of dried probiotics during storage. Therefore, this study aimed to evaluate the effect of spray-drying parameters on the survival of Lactococcus lactis A12 after drying and exposure to gastrointestinal conditions. A combined mixture-process design was carried out by evaluating three factors: whey (10–30% w/v), maltodextrin (10–30% w/v), and atomization pressure (1.0–1.5 bar). As the main results, a high concentration of whey (30% w/v), low concentration of maltodextrin (10% w/v), and high atomization pressure (1.4 bar) improved survival of spray-dried L. lactis A12 after drying and exposure to pH 3.00 or bile salts with survival rates ranged within 69.25 to 86.24%, 65.89–98.93%, and 89.09–100%, respectively. Under optimal conditions, spray-dried probiotic powder with wall materials (encapsulated) exhibited higher glass transition temperature (64.44 vs 12.65 °C), and lower hygroscopicity (12.65 vs 64.44%) than spray-dried probiotic without wall materials (non-encapsulated). Moreover, SD probiotic powder exhibited the highest survival rate (85.88%) at 4 °C during 60 days of storage in comparison to 25 °C and 37 °C which did not survive. Finally, spray-dried L. lactis A12 was included in fish feed and exhibited a survival rate of 80.83% when it was stored at 4 °C after 60 days. It can be concluded that the use of encapsulating materials, particularly whey and maltodextrin, improved the physical and thermal stability of L. lactis A12 powder during drying and storage. Also, the results from the stability of supplemented fish feed suggested that L. lactis A12 could be included in fish feed.
Repeated sleep disruption in mice leads to persistent shifts in the fecal microbiome and metabolome
It has been established in recent years that the gut microbiome plays a role in health and disease, potentially via alterations in metabolites that influence host physiology. Although sleep disruption and gut dysbiosis have been associated with many of the same diseases, studies investigating the gut microbiome in the context of sleep disruption have yielded inconsistent results, and have not assessed the fecal metabolome. We exposed mice to five days of sleep disruption followed by four days of ad libitum recovery sleep, and assessed the fecal microbiome and fecal metabolome at multiple timepoints using 16S rRNA gene amplicons and untargeted LC-MS/MS mass spectrometry. We found global shifts in both the microbiome and metabolome in the sleep-disrupted group on the second day of recovery sleep, when most sleep parameters had recovered to baseline levels. We observed an increase in the Firmicutes:Bacteroidetes ratio, along with decreases in the genus Lactobacillus, phylum Actinobacteria, and genus Bifidobacterium in sleep-disrupted mice compared to control mice. The latter two taxa remained low at the fourth day post-sleep disruption. We also identified multiple classes of fecal metabolites that were differentially abundant in sleep-disrupted mice, some of which are physiologically relevant and commonly influenced by the microbiome. This included bile acids, and inference of microbial functional gene content suggested reduced levels of the microbial bile salt hydrolase gene in sleep-disrupted mice. Overall, this study adds to the evidence base linking disrupted sleep to the gut microbiome and expands it to the fecal metabolome, identifying sleep disruption-sensitive bacterial taxa and classes of metabolites that may serve as therapeutic targets to improve health after poor sleep.
Knot Energy, Complexity, and Mobility of Knotted Polymers
The Coulomb energy E C is defined by the energy required to charge a conductive object and scales inversely to the self–capacity C , a basic measure of object size and shape. It is known that C is minimized for a sphere for all objects having the same volume, and that C increases as the symmetry of an object is reduced at fixed volume. Mathematically similar energy functionals have been related to the average knot crossing number 〈m〉, a natural measure of knot complexity and, correspondingly, we find E C to be directly related to 〈m〉 of knotted DNA. To establish this relation, we employ molecular dynamics simulations to generate knotted polymeric configurations having different length and stiffness, and minimum knot crossing number values m for a wide class of knot types relevant to the real DNA. We then compute E C for all these knotted polymers using the program ZENO and find that the average Coulomb energy 〈 E C 〉 is directly proportional to 〈m〉. Finally, we calculate estimates of the ratio of the hydrodynamic radius, radius of gyration, and the intrinsic viscosity of semi–flexible knotted polymers in comparison to the linear polymeric chains since these ratios should be useful in characterizing knotted polymers experimentally.
Passive epidemiological surveillance in wildlife in Costa Rica identifies pathogens of zoonotic and conservation importance
Epidemiological surveillance systems for pathogens in wild species have been proposed as a preventive measure for epidemic events. These systems can minimize the detrimental effects of an outbreak, but most importantly, passive surveillance systems are the best adapted to countries with limited resources. Therefore, this research aimed to evaluate the technical and infrastructural feasibility of establishing this type of scheme in Costa Rica by implementing a pilot program targeting the detection of pathogens of zoonotic and conservation importance in wildlife. Between 2018 and 2020, 85 carcasses of free-ranging vertebrates were admitted for post-mortem and microbiology analysis. However, we encountered obstacles mainly related to the initial identification of cases and limited local logistics capacity. Nevertheless, this epidemiological surveillance scheme allowed us to estimate the general state of health of the country’s wildlife by establishing the causes of death according to pathological findings. For instance, 60% (51/85) of the deaths were not directly associated with an infectious agent. Though in 37.6% (32/85) of these cases an infectious agent associated or not with disease was detected. In 27.1% (23/85) of the cases, death was directly related to infectious agents. Furthermore, 12.9% (11/85), the cause of death was not determined. Likewise, this wildlife health monitoring program allowed the detection of relevant pathogens such as Canine Distemper Virus, Klebsiella pneumoniae , Angiostrongylus spp., Baylisascaris spp., among others. Our research demonstrated that this passive surveillance scheme is cost-effective and feasible in countries with limited resources. This passive surveillance can be adapted to the infrastructure dedicated to monitoring diseases in productive animals according to the scope and objectives of monitoring wildlife specific to each region. The information generated from the experience of the initial establishment of a WHMP is critical to meeting the challenges involved in developing this type of scheme in regions with limited resources and established as hotspots for emerging infectious diseases.
Evaluator effect on the ultrasound measurement of subcutaneous fat deposition and loin eye area from weaning to slaughter lambs
Background and Aim: Ultrasound is a non-invasive technique that enables animal evaluation and body condition classification of animals. Although it is not difficult to obtain an image, the analysis of this image can influence results quality. This study aimed to evaluate the repeatability and reproducibility of the technician trained in image interpretation obtained using different ultrasound frequencies. Materials and Methods: Ninety-six lambs were used, ranging in weight from 15 to 40 kg. The images were captured using a linear probe of 13 cm, with a 3.5 megahertz (MHz) frequency and an acoustic couplant aid \"standoff\" or using a multifrequency transducer (6 and 8 MHz), on B mode, with a linear probe and 8.0 MHz frequency. All measurements were performed by the same technician, on the left side, between the 12th and 13th rib. Five different evaluators, at two different times, with aid of Image J software measured the loin eye area (LEA; only for images obtained with 3.5 MHz), Longissimus thoracis et lumborum depth (DLM), subcutaneous fat thickness (SFT), subcutaneous fat thickness plus skin (SFST), and skin thickness (ST). Results: For LEA, DLM, SFT, SFST, and ST, variation was observed (p<0.01) between evaluators; however, there was no difference (p>0.05) between the 2 times of evaluation. Images measurements obtained with a frequency of 8.0 MHz had better repeatability indices and reproducibility indices. Accordingly, the identity test demonstrated that measurements performed on images obtained using 3.5 or 8.0 MHz were not equivalent. Conclusion: Ultrasound image measurements obtained using an 8.0 MHz frequency were more accurate and precise. It is important to use only one evaluator or providing the simultaneous training for all evaluators.
Deleterious oral habits related to vertical, transverse and sagittal dental malocclusion in pediatric patients
Background Malocclusion is highly reported among mixed dentition cases. Therefore, we aimed to determine the relationship of dental malocclusions in the vertical, transverse, sagittal planes with deleterious habits in pediatric patients. Methods A cross-sectional analytical study was carried out on 155 children aged 6–12 years attended at the clinic of the School of Dentistry of Universidad Nacional Mayor de San Marcos in 2017. Results Among 155 evaluated patients, 45.3% had vertical malocclusion, 52.0% had sagittal malocclusion and 13.6% had transverse malocclusion. The most frequent type of malocclusion in the vertical plane was anterior deep bite (22.2%), in the transverse plane, the edge-to-edge bite (7.1%) and the anterior crossbite (6.5%) were less frequent. Finally, in the sagittal plane, Class II Div 1 (20%) and Class III (20.7%) were the most frequent. Among the most common deleterious habits, anteroposition (58.7%) and mixed breathing (51.0%) were observed in contrast to the habit of retroposition, lip sucking and mouth breathing, which were the least frequent. Considering age and sex, children who have an atypical swallowing habit are more likely to have malocclusion in all three planes of space. Conclusions It is concluded that there is an association between the deleterious habits with the different types of malocclusions in the different planes of the space, being the atypical swallowing a habit that should be early diagnosed and treated interdisciplinary.
Moringa Extract to Modulate Rumen Fermentation and Lactation Performance of Ewes
This study aimed to evaluate the supplementation of aqueous extract of Moringa oleifera (AEMO) as a natural ruminal modulator to improve the lactation performance of ewes. The AEMO was prepared by chopping Moringa oleifera leaves and diluting them in distilled water (163.3 g DM/L). Twelve ewes were used in a replicated 3 × 3 Latin square, with periods of 14 days (assessments on the last five days of each period). Treatments were as follows: 20 mL of water as Control, 20 mL of AEMO (20-AEMO), and 40 mL of AEMO (40-AEMO). Ewes were milked twice a day (7:30 a.m. and 2:30 p.m.). Diet corresponds to grain mix (at 3% of BW) and hay ad libitum. We determined the intake, digestibility, fermentative measurements, metabolic measurements, and milk production and composition. Intake and digestibility were not affected by AEMO. Milk yield and the concentrations of fat, protein, and lactose were numerically lower in ewes supplemented with 20-AEMO. A linear decrease in milk protein yield was observed when the highest extract level (40-AEMO) was used. Ruminal pH did not differ among treatments; however, there was a tendency for reduced acetate and increased propionate concentrations, which corresponded with a non-significant numerical decrease in methane estimates in 40-AEMO group. Blood and urinary parameters were not affected by AEMO supplementation. Inclusion of Moringa extracts as an additive in lactating ewes diet does not affect intake and nutrient digestibility, but tends to affect ruminal fermentation and microbial synthesis, with possible changes in methane emission estimation, and impair milk protein production. Therefore, we recommend studies with different extract concentrations to investigate possible effects on rumen fermentation and the synthesis of milk compounds.
Aposematism facilitates the diversification of parental care strategies in poison frogs
Many organisms have evolved adaptations to increase the odds of survival of their offspring. Parental care has evolved several times in animals including ectotherms. In amphibians, ~ 10% of species exhibit parental care. Among these, poison frogs (Dendrobatidae) are well-known for their extensive care, which includes egg guarding, larval transport, and specialized tadpole provisioning with trophic eggs. At least one third of dendrobatids displaying aposematism by exhibiting warning coloration that informs potential predators about the presence of defensive skin toxins. Aposematism has a central role in poison frog diversification, including diet specialization, and visual and acoustic communication; and it is thought to have impacted their reproductive biology as well. We tested the latter association using multivariate phylogenetic methods at the family level. Our results show complex relationships between aposematism and certain aspects of the reproductive biology in dendrobatids. In particular, aposematic species tend to use more specialized tadpole-deposition sites, such as phytotelmata, and ferry fewer tadpoles than non-aposematic species. We propose that aposematism may have facilitated the diversification of microhabitat use in dendrobatids in the context of reproduction. Furthermore, the use of resource-limited tadpole-deposition environments may have evolved in tandem with an optimal reproductive strategy characterized by few offspring, biparental care, and female provisioning of food in the form of unfertilized eggs. We also found that in phytotelm-breeders, the rate of transition from cryptic to aposematic phenotype is 17 to 19 times higher than vice versa. Therefore, we infer that the aposematism in dendrobatids might serve as an umbrella trait for the evolution and maintenance of their complex offspring-caring activities.