804 resultados para body-on-a chip
Resumo:
To investigate the effects of body size and water temperature on feeding and growth in the sea cucumber Apostichopus japonicus (Selenka), the maximum rate of food consumption in terms of energy (C-maxe; J day(-1)) and the specific growth rate in terms of energy (SGRe; % day(-1)) in animals of three body sizes (mean +/- SE) - large (134.0 +/- 3.5 g), medium (73.6 +/- 2.2 g) and small (36.5 +/- 1.2 g) - were determined at water temperatures of 10, 15, 20, 25 and 30 degrees C. Maximum rate of food consumption in terms of energy increased and SGRe decreased with increasing body weight at 10, 15 and 20 degrees C. This trend, however, was not apparent at 25 and 30 degrees C, which could be influenced by aestivation. High water temperatures (above 20 degrees C) were disadvantageous to feeding and growth of this animal; SGRe of A. japonicus during aestivation was negative. The optimum temperatures for food consumption and for growth were similar and were between 14 and 15 degrees C, and body size seemed to have a slight effect on the optimal temperature for food consumption or growth. Because aestivation of A. japonicus was temperature dependent, the present paper also documented the threshold temperatures to aestivation as indicated by feeding cessation. Deduced from daily food consumption of individuals, the threshold temperature to aestivation for large and medium animals (73.3-139.3 g) was 24.5-25.5 degrees C, while that for small animals (28.9-40.7 g) was between 25.5 and 30.5 degrees C. These values are higher than previous reports; differences in sign of aestivation, experimental condition and dwelling district of test animals could be the reasons.
Resumo:
A 21-d laboratory experiment was conducted to study, the phosphorus (P) utilization of two different diets by redlip mullet Liza haematocheila T. & S. Sand-filtered water in salinity 30 and temperature 25 degrees C was used. Twenty-nine fish individuals were divided into three groups: 11 to group 1 (G1) fed on diet 1, 11 to group 2 (G2) fed on diet 2, and 7 to contrast group. Diet 1 was a commercial feed, more valuable in nutrition than diet 2 that similar to natural detritus. The results show the intake phosphorus (IP) of G1 was significantly higher than that of G2, and both increased linearly with body size at a certain amount of diet. The retention phosphorus (RP) in fish of G1 was lower than G2. The relationship between retention phosphorus and body size was positive and stronger in G2. Significant difference in faecal phosphorus (FP) was found between G1 and G2. Body size significantly impacted the excretion phosphorus (EP) in G1 but G2. The loss of intake phosphor-us in G1 was 10.83-20.27 mg per g fish weight gain, higher than that in G2 for 6.63-9.56. Of the phosphor-us, about 10% was allocated into growth, 50% in faeces, and the rest lost in excretion. The main part of phosphorus was lost in faeces but excretion. The phosphorus budget of the fish could be described as 100IP = 7.40RP + 47.39FP + 36.63EP (Diet 1) or 100IP = 11.93RP + 56.64FP + 21.76EP (Diet 2).
Resumo:
Shrimps Litopenaeus vannamei with initial body weight of 2.108 +/- 0.036 g were sampled for specific growth rates (SGR) and body color measurements for 50 days under different light sources (incandescent lamp, IL; cool-white fluorescent lamp, FL; metal halide lamp, MHL; and control without lamp) and different illumination methods (illumination only in day, IOD, and illumination day and night, IDN). Body color of L. vannamei was measured according to the free astaxanthin concentration (FAC) of shrimp. The SGR, food intake (FI), feed conversion efficiency (FCE) and FAC of shrimps showed significant differences among the experimental treatment groups (P < 0.05). Maximum and minimum SGR occurred under IOD by MHL and IDN by FL, respectively (difference 56.34%). The FI of shrimp for the control group did not rank lowest among treatments, confirming that shrimp primarily use scent, not vision, to search for food. FI and FCE of shrimps were both the lowest among treatment groups under IDN by FL and growth was slow, thus FL is not a preferred light source for shrimp culture. Under IOD by MHL, shrimps had the highest FCE and the third highest FI among treatment groups ensuring rapid growth. FAC of shrimp were about 3.31 +/- 0.20 mg/kg. When under IOD by MHL and IDN by FL, FAC was significantly higher than the other treatments (P < 0.05). To summarize, when illuminated by MHL, L. vannamei had not only vivid body color due to high astaxanthin concentration but also rapid growth. Therefore, MHL is an appropriate indoor light source for shrimp super-intensive culture. SGR of shrimp was in significantly negative correlation to FAC of shrimp (P < 0.05). Thus, when FAC increased, SGR did not always follow, suggesting that the purpose of astaxanthin accumulation was not for growth promotion but for protection against intense light. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Forty-five male yaks (born April 2001) were studied to determine how seasonal changes on the Qinghai-Tibetan plateau affected BW and body composition. Thirty yaks were weighed monthly from birth to 26 mo of age to determine seasonal changes in BW. The remaining 15 yaks were allocated randomly to five groups (three yaks per group), designated for slaughter at 13, 15, 18, 22, and 25 mo to measure seasonal effects on body chemical composition. All yaks were grazed on the alpine-meadow grassland of the plateau without any supplementation. All BW and body composition data were calculated on an individual basis. Body weight and body composition data were both compared across seven growth periods spanning 2 yr and defined by season. From April (birth) to December 2001 of the first growing season, yak BW increased (P < 0.01); however, during the subsequent cold season (December 2001 to May 2002), BW decreased (P < 0.01). The second growing season ran from May 2002 (13 mo of age) to October 2002 (18 mo of age), and the second live weight-loss season ran from October 2002 until May 2003. The weight loss experienced by yaks during the first weight loss season was 25.64% of the total weight gain in the first growing season. The weight loss experienced by yaks during the second weight-loss season was 29.73% of the total weight gain in the second growing season. Energy retention in the second growing season was 291.07 MJ, 50.8% of which was consumed during the subsequent cold season. Energy accumulation in the summer (from May to July) and fall (from July to October) of the second growing season did not differ (5.01 and 6.30 MJ/kg of EBW gain, respectively; P = 0.63). The energy mobilized during the second winter (from October 2002 to February 2003) was 16.49 MJ/kg of EBW, and in the second spring (from February to May 2003), it was 9.06 MJ/kg of EBW. These data suggest that the decrease in grazing yak BW during the first cold season is much less than during the second cold season, and that the energy content per unit of BW mobilized is greater (P = 0.02) in winter than in spring. Results from this study demonstrate highly efficient compensatory growth in grazing yaks following the first weight loss period during the first cold season. This benefit could be exploited by herders to improve yak production. Yaks may have developed a type of self-protection mechanism to overcome the long cold seasons in the Qinghai-Tibetan plateau.
Resumo:
Particle filtering is a popular method used in systems for tracking human body pose in video. One key difficulty in using particle filtering is caused by the curse of dimensionality: generally a very large number of particles is required to adequately approximate the underlying pose distribution in a high-dimensional state space. Although the number of degrees of freedom in the human body is quite large, in reality, the subset of allowable configurations in state space is generally restricted by human biomechanics, and the trajectories in this allowable subspace tend to be smooth. Therefore, a framework is proposed to learn a low-dimensional representation of the high-dimensional human poses state space. This mapping can be learned using a Gaussian Process Latent Variable Model (GPLVM) framework. One important advantage of the GPLVM framework is that both the mapping to, and mapping from the embedded space are smooth; this facilitates sampling in the low-dimensional space, and samples generated in the low-dimensional embedded space are easily mapped back into the original highdimensional space. Moreover, human body poses that are similar in the original space tend to be mapped close to each other in the embedded space; this property can be exploited when sampling in the embedded space. The proposed framework is tested in tracking 2D human body pose using a Scaled Prismatic Model. Experiments on real life video sequences demonstrate the strength of the approach. In comparison with the Multiple Hypothesis Tracking and the standard Condensation algorithm, the proposed algorithm is able to maintain tracking reliably throughout the long test sequences. It also handles singularity and self occlusion robustly.
Resumo:
The objective of this paper is to investigate the effect of the pad size ratio between the chip and board end of a solder joint on the shape of that solder joint in combination with the solder volume available. The shape of the solder joint is correlated to its reliability and thus of importance. For low density chip bond pad applications Flip Chip (FC) manufacturing costs can be kept down by using larger size board pads suitable for solder application. By using “Surface Evolver” software package the solder joint shapes associated with different size/shape solder preforms and chip/board pad ratios are predicted. In this case a so called Flip-Chip Over Hole (FCOH) assembly format has been used. Assembly trials involved the deposition of lead-free 99.3Sn0.7Cu solder on the board side, followed by reflow, an underfill process and back die encapsulation. During the assembly work pad off-sets occurred that have been taken into account for the Surface Evolver solder joint shape prediction and accurately matched the real assembly. Overall, good correlation was found between the simulated solder joint shape and the actual fabricated solder joint shapes. Solder preforms were found to exhibit better control over the solder volume. Reflow simulation of commercially available solder preform volumes suggests that for a fixed stand-off height and chip-board pad ratio, the solder volume value and the surface tension determines the shape of the joint.
I'll have what she's having: Effects of social influence and body type on the food choices of others
Resumo:
This research examines how the body type of consumers affects the food consumption of other consumers around them. We find that consumers anchor on the quantities others around them select but that these portions are adjusted according to the body type of the other consumer. We find that people choose a larger portion following another consumer who first selects a large quantity but that this portion is significantly smaller if the other is obese than if she is thin. We also find that the adjustment is more pronounced for consumers who are low in appearance self-esteem and that it is attenuated under cognitive load. © 2009 by Journal of Consumer Research, Inc.
Resumo:
Current strategies to limit macrophage adhesion, fusion and fibrous capsule formation in the foreign body response have focused on modulating material surface properties. We hypothesize that topography close to biological scale, in the micron and nanometric range, provides a passive approach without bioactive agents to modulate macrophage behavior. In our study, topography-induced changes in macrophage behavior was examined using parallel gratings (250 nm-2 mum line width) imprinted on poly(epsilon-caprolactone) (PCL), poly(lactic acid) (PLA) and poly(dimethyl siloxane) (PDMS). RAW 264.7 cell adhesion and elongation occurred maximally on 500 nm gratings compared to planar controls over 48 h. TNF-alpha and VEGF secretion levels by RAW 264.7 cells showed greatest sensitivity to topographical effects, with reduced levels observed on larger grating sizes at 48 h. In vivo studies at 21 days showed reduced macrophage adhesion density and degree of high cell fusion on 2 mum gratings compared to planar controls. It was concluded that topography affects macrophage behavior in the foreign body response on all polymer surfaces examined. Topography-induced changes, independent of surface chemistry, did not reveal distinctive patterns but do affect cell morphology and cytokine secretion in vitro, and cell adhesion in vivo particularly on larger size topography compared to planar controls.
Resumo:
Although the release of nitric oxide (NO) from biomaterials has been shown to reduce the foreign body response (FBR), the optimal NO release kinetics and doses remain unknown. Herein, polyurethane-coated wire substrates with varying NO release properties were implanted into porcine subcutaneous tissue for 3, 7, 21 and 42 d. Histological analysis revealed that materials with short NO release durations (i.e., 24 h) were insufficient to reduce the collagen capsule thickness at 3 and 6 weeks, whereas implants with longer release durations (i.e., 3 and 14 d) and greater NO payloads significantly reduced the collagen encapsulation at both 3 and 6 weeks. The acute inflammatory response was mitigated most notably by systems with the longest duration and greatest dose of NO release, supporting the notion that these properties are most critical in circumventing the FBR for subcutaneous biomedical applications (e.g., glucose sensors).
Resumo:
A lateral on-chip electron-impact ion source utilizing a carbon nanotube field emission electron source was fabricated and characterized. The device consists of a cathode with aligned carbon nanotubes, a control grid, and an ion collector electrode. The electron-impact ionization of He, Ar, and Xe was studied as a function of field emission current and pressure. The ion current was linear with respect to gas pressure from 10-4 to 10-1 Torr. The device can operate as a vacuum ion gauge with a sensitivity of approximately 1 Torr-1. Ion currents in excess of 1 μA were generated. © 2007 American Institute of Physics.
Resumo:
Obesity, currently an epidemic, is a difficult disease to combat because it is marked by both a change in body weight and an underlying dysregulation in metabolism, making consistent weight loss challenging. We sought to elucidate this metabolic dysregulation resulting from diet-induced obesity (DIO) that persists through subsequent weight loss. We hypothesized that weight gain imparts a change in “metabolic set point” persisting through subsequent weight loss and that this modification may involve a persistent change in hepatic AMP-activated protein kinase (AMPK), a key energy-sensing enzyme in the body. To test these hypotheses, we tracked metabolic perturbations through this period, measuring changes in hepatic AMPK. To further understand the role of AMPK we used AICAR, an AMPK activator, following DIO. Our findings established a more dynamic metabolic model of DIO and subsequent weight loss. We observed hepatic AMPK elevation following weight loss, but AICAR administration without similar dieting was unsuccessful in improving metabolic dysregulation. Our findings provide an approach to modeling DIO and subsequent dieting that can be built upon in future studies and hopefully contribute to more effective long-term treatments of obesity.
Resumo:
BACKGROUND: Curcumin is a natural product that is often explored by patients with cancer. Weight loss due to fat and muscle depletion is a hallmark of pancreatic cancer and is associated with worse outcomes. Studies of curcumin's effects on muscularity show conflicting results in animal models. METHODS AND RESULTS: Retrospective matched 1:2 case-control study to evaluate the effects of curcumin on body composition (determined by computerized tomography) of 66 patients with advanced pancreatic cancer (22 treated,44 controls). Average age (SEM) was 63(1.8) years, 30/66(45%) women, median number of prior therapies was 2, median (IQR) time from advanced pancreatic cancer diagnosis to baseline image was 7(2-13.5) months (p>0.2, all variables). All patients lost weight (3.3% and 1.3%, treated vs. control, p=0.13). Treated patients lost more muscle (median [IQR] percent change -4.8[-9.1,-0.1] vs. -0.05%[-4.2, 2.6] in controls,p<0.001) and fat (median [IQR] percent change -6.8%[-15,-0.6] vs. -4.0%[-7.6, 1.3] in controls,p=0.04). Subcutaneous fat was more affected in the treated patients. Sarcopenic patients treated with curcumin(n=15) had survival of 169(115-223) days vs. 299(229-369) sarcopenic controls(p=0.024). No survival difference was found amongst non-sarcopenic patients. CONCLUSIONS: Patients with advanced pancreatic cancer treated with curcumin showed significantly greater loss of subcutaneous fat and muscle than matched untreated controls.
Resumo:
Nowadays, the idea of a reciprocal influence of physiological and psychological processes seems to be widely accepted. For instance, current theories of embodied emotion suggest that knowledge about an emotion concept involves simulations of bodily experienced emotional states relevant to the concept. In line with this framework, the present study investigated whether actual levels of physiological arousal interact with the processing of emotional words. Participants performed 2 blocks of an attentional blink task, once after a cycling session (increased arousal) and once after a relaxation session (reduced arousal). Concretely, participants were instructed to detect and report 2 target words (T1 and T2) presented among a series of nonword distractors. T1 and T2 were either neutral, high arousal, or low arousal words. Results revealed that increased physiological arousal led to improved reports of high arousal T2 words, whereas reduced physiological arousal led to improved reports of low arousal T2 words. Neutral T2 remained unaffected by the arousing conditions. These findings emphasize that actual levels of physiological arousal modulate the cognitive access to arousal (in-)congruent emotional concepts and suggest a direct grounding of emotion knowledge in our bodily systems of arousal.
Resumo:
This paper describes how modeling technology has been used in providing fatigue life time data of two flip-chip models. Full-scale three-dimensional modeling of flip-chips under cyclic thermal loading has been combined with solder joint stand-off height prediction to analyze the stress and strain conditions in the two models. The Coffin-Manson empirical relationship is employed to predict the fatigue life times of the solder interconnects. In order to help designers in selecting the underfill material and the printed circuit board, the Young's modulus and the coefficient of thermal expansion of the underfill, as well as the thickness of the printed circuit boards are treated as variable parameters. Fatigue life times are therefore calculated over a range of these material and geometry parameters. In this paper we will also describe how the use of micro-via technology may affect fatigue life