3,076 research outputs found
Wideband bandpass filters using a novel thick metallization technology
A new class of wideband bandpass filters based on using thick metallic bars as microwave
resonators is presented in this work. These bars provide a series of advantages over fully planar printed
technologies, including higher coupling levels between resonators, higher unloaded quality factors QU ,
and larger bandwidths implemented with compact structures. In comparison to dielectric and waveguide
resonators filters, higher bandwidths together with lower weight and footprint reduction are achieved with
the proposed thick bars technology. Moreover, thick bar resonators can easily be coupled to an additional
resonance excited in a box used for shielding, allowing to realize transversal topologies able to implement
transmission zeros at desired frequencies. To illustrate the capabilities of this technology, three microwave
filters with different topologies have been designed. One of the designed filters has been manufactured and
tested using copper bars inside an aluminum housing partially filled with Teflon. Measured data demonstrates
a fractional bandwidth of FBW = 32%, spurious free range SFR > 50%, unloaded quality factor of
QU = 1180, insertion losses over 0.16 dB and return losses over 20 dB, without requiring any post-tuning
operation on the prototype. This result confirms the exciting performance of the proposed technology for
wideband applications.This work was supported in part by the National Science Foundation with CAREER under Grant ECCS-1749177, in part by the Spanish Government, Ministerio de Educación, Cultura y Deporte under Grant FPU15/02883, and in part by the Ministerio de Economía y Competitividad through the Coordinated Project under Grant TEC2016-75934-C4-R and Grant PRX18/00092
Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter
NEXT is a new experiment to search for neutrinoless double beta decay using a
100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires
excellent energy resolution, which can be achieved in a Xe TPC with
electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good
candidates for the scintillation readout. The performance of this
photomultiplier, used as VUV photosensor in a gas proportional scintillation
counter, was investigated. Initial results for the detection of primary and
secondary scintillation produced as a result of the interaction of 5.9 keV
X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are
presented. An energy resolution of 8.0% was obtained for secondary
scintillation produced by 5.9 keV X-rays. No significant variation of the
primary scintillation was observed for different pressures (1, 2 and 3 bar) and
for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating
negligible recombination luminescence. A primary scintillation yield of 81 \pm
7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72
\pm 6 eV to produce a primary scintillation photon in xenon.Comment: 16 pages, 10 figures, accepted for publication in JINS
Polypyrrole Nanopipes as a Promising Cathode Material for Li-ion Batteries and Li-ion Capacitors : Two-in-One Approach
Lithium ion capacitor (LIC) is a promising energy storage system that can simultaneously provide high energy with high rate (high power). Generally, LIC is fabricated using capacitive cathode (activated carbon, AC) and insertion-type anode (graphite) with Li-ion based organic electrolyte. However, the limited specific capacities of both anode and cathode materials limit the performance of LIC, in particular energy density. In this context, we have developed "two in one" synthetic approach to engineer both cathode and anode from single precursor for high performance LIC. Firstly, we have engineered a low cost 1D polypyrrole nanopipes (PPy-NPipes), which was utilized as cathode material and delivered a maximum specific capacity of 126 mAh/g, far higher than that of conventional AC cathodes (35 mAh/g). Later, N doped carbon nanopipes (N-CNPipes) was derived from direct carbonization of PPy-NPipes and successfully applied as anode material in LIC. Thus, a full LIC was fabricated using both pseudo-capacitive cathode (PPy-NPipes) and anode (N-CNPipes) materials, respectively. The cell delivered a remarkable specific energy of 107 Wh/kg with maximum specific power of 10 kW/kg and good capacity retention of 93 % over 2000 cycles. Thus, this work provide a new approach of utilization of nanostructured conducting polymers as a promising pseudocapacitive cathode for high performance energy storage systems
Bioerosion on late Quaternary Planktonic Foraminifera related to paleoproductivity in the western South Atlantic
Planktonic Foraminifera are widely used in paleoceanographic reconstructions, although studies of their trophic interactions are still rare, especially those focusing on predation. Drilling holes are the most frequent traces of bioerosion in foraminifer tests, but environmental factors that control bioerosion are not yet understood. To determine if paleoceanographic variables are associated with bioerosion rates in late Quaternary planktonic foraminifers of the western South Atlantic, geochemical and assemblage analyses were made on a 46 kyr record from a piston core. An age model was constructed based on 10 AMS 14C dates. To reconstruct the paleoproductivity, δ13C, benthic/planktonic foraminifer and the relative abundances of Globigerina bulloides and Globigerinoides ruber (high and low productivity, respectively) were used. Bioeroded tests were counted and found in 21 of the 25 identified species, with frequencies ranging from 8.84% to 16.7%. Bioerosion was different in two groups identified by cluster analysis, with a higher intensity during glacial times, showing a strong correlation with paleoceanographic fluctuations. Paleoproductivity estimates and bioerosion rates show a significant correlation, suggesting that bioerosion is more frequent in eutrophic environments and more inhibited in oligotrophic conditions. However, even with a strong correlation between bioerosion and productivity, there is also a negative correlation with sea surface temperature in the study area. Since conditions that promote higher productivity are accompanied by a decrease in surface temperature, the precise distinction between the influence of both variables is hampered. Further research will allow us to explore the potential of planktonic foraminiferal bioerosion as a tool in paleoceanographic studies
Enhancing Transport Efficiency by Hybrid Routing Strategy
Traffic is essential for many dynamic processes on real networks, such as
internet and urban traffic systems. The transport efficiency of the traffic
system can be improved by taking full advantage of the resources in the system.
In this paper, we propose a dual-strategy routing model for network traffic
system, to realize the plenary utility of the whole network. The packets are
delivered according to different "efficient routing strategies" [Yan, et al,
Phys. Rev. E 73, 046108 (2006)]. We introduce the accumulate rate of packets,
{\eta} to measure the performance of traffic system in the congested phase, and
propose the so-called equivalent generation rate of packet to analyze the
jamming processes. From analytical and numerical results, we find that, for
suitable selection of strategies, the dual- strategy system performs better
than the single-strategy system in a broad region of strategy mixing ratio. The
analytical solution to the jamming processes is verified by estimating the
number of jammed nodes, which coincides well with the result from simulation.Comment: 6 pages, 3 figure
Impact of Multiple Sclerosis and Its Association with Depression: An Analytical Case-Control Investigation
Multiple sclerosis (MS) is a neurological, chronic, inflammatory, and progressive disease with musculoskeletal problems and neurodegenerative disorders that causes worsening of the health status of patients. The aim of this study was to determine the level of depression in MS patients compared to a population of healthy subjects. The established sample size was 116 subjects matched with the same age, sex, and body mass index. The subjects were recruited from different multiple sclerosis associations and neurology clinics in different public health areas (case group n = 58) and healthy subjects from the same locality (control group n = 58). The scores and categories of the Beck Depression Inventory (BDI) in its Spanish version were collected. There was a clear statistically significant difference (p < 0.05) in the BDI scores between both groups. As a result, we found that the subjects with MS presented worse results with BDI = 9.52 ± 7.70 points compared to the healthy subjects with a BDI score = 5.03 ± 5.14. Within the BDI categories, there were statistically significant differences (p < 0.001), which were greater for the MS group. Depression is a dangerous factor for MS patients, being a trigger for a poorer quality of life.Partial funding for open access charge: Universidad de Málag
Kinesiophobia Levels in Patients with Multiple Sclerosis: A Case-Control Investigation
[Abstract] Fear of movement or kinesiophobia is an irrational fear of physical movement and fatigue
that causes a limitation of functional capacity and decreased physical activity. The purpose of
this study was to ascertain the level of kinesiophobia in people with multiple sclerosis (pwMS)
and compare it with a group of healthy people, through the Tampa Scale for Kinesiophobia with
11 items (TSK-11). Method: A total of 116 subjects were recruited in a multicenter case-control study;
58 subjects suffered from MS and 58 were healthy subjects from different associations and the same
locality. To assess the levels of fear of movement, the Spanish version of the TSK-11 self-questionnaire
was used. Results: Most pwMS suffer from some degree of kinesiophobia (TSK-11 18), and
60.3% had moderate to maximum kinesiophobia scores (TSK-11 25). In contrast, healthy subjects
presented a percentage of kinesiophobia from none to moderate (82.7%). Conclusions: Kinesiophobia
is higher in pwMS than in the healthy control group. Accordingly, individuals showing pwMS should
be assessed and monitored in order to diagnosed initial kinesiophobia levels, to allow planning
treatment and preventive care activities that may improve the foot health and overall health in this
group of patient
Separation of Oligosaccharides from Lotus Seeds via Medium-pressure Liquid Chromatography Coupled with ELSD and DAD
peer-reviewedLotus seeds were identified by the Ministry of Public Health of China as both food and medicine. One general function of lotus seeds is to improve intestinal health. However, to date, studies evaluating the relationship between bioactive compounds in lotus seeds and the physiological activity of the intestine are limited. In the present study, by using medium pressure liquid chromatography coupled with evaporative light-scattering detector and diode-array detector, five oligosaccharides were isolated and their structures were further characterized by electrospray ionization-mass spectrometry and gas chromatography-mass spectrometry. In vitro testing determined that LOS3-1 and LOS4 elicited relatively good proliferative effects on Lactobacillus delbrueckii subsp. bulgaricus. These results indicated a structure-function relationship between the physiological activity of oligosaccharides in lotus seeds and the number of probiotics applied, thus providing room for improvement of this particular feature. Intestinal probiotics may potentially become a new effective drug target for the regulation of immunity
Lettuce Production under Mini-PV Modules Arranged in Patterned Designs
The growing need for clean energy and food production are favoring the use of underused spaces, such as rooftops. This study aims to demonstrate the compatibility of the use of rooftops both for the production of photovoltaic energy and for the production of food, despite the fact that both compete for the same resource, sunlight (rooftop agrivoltaic). In the experiment reported in this study, which was carried out in Almería (Spain) during the spring and summer of 2021, three shade treatments were tested for a lettuce crop, produced by photovoltaic modules with different arrangements: concentrated shade (CS), scattered shade (SS) and full sun (FS). This experiment was repeated in two seasons with high radiation levels and temperature. The results show that in these environmental conditions, the cultivation of plants that demand little sunlight, such as lettuce, is compatible with the shading produced by photovoltaic panels. In addition, it is shown that the same percentage of the area covered with shade (22%), but using mini-PV modules arranged in patterns, improves the productivity (fresh weight, dry matter, number of leaves, maximum length and dry matter of roots) of lettuce cultivation, both in spring and summer
- …