Unraveling the Lagged Effect of Hydro-meteorological Conditions On the Trophic State of a Reservoir By Applying Dynamic Regression

In this study we develop a novel approach to quantify the relative importance of hydro-meteorological (HM) conditions on the trophic state index (TSI) of a water reservoir (San Roque, Córdoba, Argentina). Seven HM variables measured at four reservoir sites and different depths over a time period of near 2 decades are used. We propose a dynamic regression model to predict the TSI from these variables aggregated over a range of time lags, which has not been applied in such a complex setting so far. By performing coefficient analysis, we quantify the relative importance of these variables on the TSI, as well as the time duration over which they have significant impact (lagged effect). Additionally, the analysis of the autoregressive and moving average (ARIMA) terms reveals the impact of the residual effects of previous trophic states on the current trophic state. We find that surface temperature and precipitation have the largest direct relationship to the TSI in the short-term, while the reservoir water level is inversely related to the TSI in the short- to mid-term. Also, the residual effects of the trophic state impact from 1 month (generally) up to 2 years (exceptionally). This approach can be applied to other water bodies affected by similar eutrophication phenomena.

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Microbiological quality of organic and conventional vegetables sold in Brazil

While searching for healthier diets, people became more attentive to organic produce. Yet, organic foods may be more susceptible to microbiological contamination because of the use of organic fertilizers, a possible source of pathogenic bacteria. In this study, 130 samples of different organic and conventional vegetable varieties sold in Brazil were analyzed for mesophilic aerobic bacteria, yeasts and molds, total coliforms, Escherichia coli and Salmonella spp. Most of the mesophilic aerobic bacteria counts in organic and conventional vegetables ranged from 6 to 7 log10 CFU/g; most of the yeasts and molds counts ranged from 5 to 6 log10 CFU/g and most of the total coliforms counts ranged from 4 to 5 log10 CFU/g. E. coli was found in 41.5% of the organic and 40.0% of the conventional vegetables, and most samples had counts ranging from 1 to 2 log10 CFU/g. Salmonella spp. was not found in any sample. Comparative analyses of the microbial counts of organic and conventional vegetables showed that some organic varieties have greater counts. However, the global results show that this is not a trend. These results indicate the need of good farming practices, and proper sanitization before consumption, to ensure food quality and safety.     

Theoretical and experimental studies of a bi-metallic heat switch for space applications

This work presents theoretical and experimental studies on a passively actuated bi-metallic heat switch for space applications. The working principle of the heat switch is based on the differential thermal expansion of distinct metals. Analytical one-dimensional and two-dimensional heat conduction models are developed to predict the thermal resistance of the heat switch, which is a function of temperature. A non-dimensional parametric analysis is performed in order to study how the design parameters affect the total thermal resistance of the heat switch. The theoretical models are also compared with experimental data obtained from a prototype of the heat switch. The agreement between theory and experiments is good.     

Effects of Temperature and Concentration on the Rheological Behavior of Polyacrylamide-Based Polymers

Polymers are high molecular weight molecules that provide high viscosity at low concentrations to the media they are inserted. In the oil industry, they are used for enhanced oil recovery and for drilling fluids, where its viscosity is an important factor for a greater efficiency. From all the polymers used by industry, the polyacrylamide and the biopolymer xantham gum are those, which appear significantly in those applications. Taking that into consideration, this work intends to study the effects of the physical, chemical and structural parameters of those polymers in their rheological behaviour, by varying their concentrations from 400 ppm to 2,000 ppm and their temperatures from 298 K to 328 K, which are values similar to those found in the field. For that, a Brookfield Viscometer-Brookfield Engineering Labs rheometer was used. The results acquired showed that the increase on the polyacrylamides ionicity generates and increase on the medium viscosity. For the temperature, its increase causes a reduction of viscosity for the low ionicity polyacrylamides, while increases the viscosity for the high ionicity ones. In the comparative study between xantham gum and polyacrylamides, it was possible to notice that, even though the biopolymer is more complex, its viscosity still is lower when compared to the polyacrylamides.     

Age-related binding deficits and the content of false memories.

The authors examined effects of age-related binding deficits on feature information in false memories for imagined objects (e.g., lollipop) that were similar in shape to seen objects (e.g., magnifying glass). In Experiment 1, location memory for seen objects was lower in older than younger adults and lower still in old-old than young-old adults. Imagined objects, when falsely called seen, were less likely to be attributed to the location of similar seen objects (i.e., congruent attributions) by old-old than young-old adults. In Experiment 2, for younger adults, displaying seen objects for less time (1 s vs. 4 s) reduced both location memory for seen objects and congruent attributions for false memories. Thus, binding deficits may influence the specific content of false memories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Twin similarity in cardiovascular stress response.

Measured blood pressure and heart rate in 12 pairs of identical and 21 pairs of fraternal male twins (aged 54–64 yrs) during a mental arithmetic task and during submersion of the S's left hand in 4°C water for 60 sec. The results suggest that certain measures of cardiovascular reactivity to laboratory stressors may be heritable for both physical and psychological stressors. The possible role of this genetic component in the etiology and course of coronary heart disease is discussed. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response surface methodology in the control of thermoplastic extrusion of starch

Effect of extrusion temperature, screw speed and moisture content on the gelatinisation properties of extruded corn starch using a single-screw extruder were studied using response surface methodology. The degree of gelatinisation can be effectively controlled by controlling the moisture content of the raw material and the extrusion temperature; control by manipulation of screw speed is also possible when the raw material has a high moisture content. The extrudate produced from starch with a low moisture content exhibited a very low retrogradation capacity, which was independent of the screw speed. It was evident that variation of operating conditions permits the production of an extrudate with various technological characteristics to meet varying food and industrial applications, and the use of response surface analysis seems to be an effective means of studying and optimising these conditions for extrusion technology.     

超奇着装的符号学意义:希普霍普风格的经典诠释和结构性分析

希普霍普风格(hiphop style)是与20世纪90年代说唱音乐文化相联系的一种充满争议的着装形式.人们对它的分析和诠释一直以符号学的结构性研究方法为基础.不同时间段中的符号学体系彼此分离,在建立这个体系中的诸多因素和所蕴含意义的关系方面,需要考虑三个编码操作(coding operations),即范式对齐(paradigmatic alignment)--极端的观点、外延意义和内涵意义(denotation and connotation)--字面的意义和延伸的意叉、修辞手段(figurative devices)--暗含的喻义.研究结果依据希普霍普风格系统符号和常规着装系统符号间的辩证关系,揭示了这一体系的结构.常规着装体系的组成要素由此得以揭示,支持希普霍鲁系统的象征性语言也被描述了出来.希普霍普风格被当作一种与超奇着装设计相关的服装体系的范例加以分析,而这种风格与普通着装形式是对立的,这种分析对相关理论的发展有着积极的意义.     

Microglial Cell Activation Increases Saturated and Decreases Monounsaturated Fatty Acid Content,but Both Lipid Species are Proinflammatory

Neuroinflammation is a component of age-related neurodegenerative diseases and cognitive decline. Saturated (SFA) and monounsaturated (MUFA) fatty acids are bioactive molecules that may play different extrinsic and intrinsic roles in neuroinflammation, serving as exogenous ligands for cellular receptors, or endogenous components of cell structural, energetic and signaling pathways. We determined the fatty acyl profile of BV2 microglial cells before and after acute activation with lipopolysaccharide (LPS). We also investigated the effect of SFA and MUFA pretreatment on the production of an invasive, neurotoxic phenotype in BV2 cells. Acute activation of BV2 microglia resulted in an increase in the relative content of SFA (12:0, 16:0, 18:0, 20:0, 22:0, and 24:0 increased significantly), and a relative decrease in the content of MUFA (16:1n7, 18:1n7, 18:1n9, 20:1n9, 24:1n9 decreased significantly). In agreement, the major stearoyl-CoA desaturase (SCD) isoform in BV2 cells, SCD2, was significantly down-regulated by LPS. We next treated cells with SFA (16:0 or 18:0) or MUFA (16:1n7 or 18:1n9), and found that levels of secreted IL6 were increased, as was secreted MMP9-mediated proteolytic activity. To test the functional significance, we treated SH-SY5Y neuronal cells with conditioned medium from BV2 cells pretreated with fatty acids, and found a small but significant induction of cell death. Our findings suggest differential intrinsic roles for SFA and MUFA in activated microglial cells, but similar extrinsic roles for these fatty acid species in inducing activation. Expansion of SFA is important during microglial cell activation, but either supplemental SFA or MUFA may contribute to chronic low-grade neuroinflammation.     

Bonding ability of self-adhesive resin-cements after dentin biomodification with hyaluronic acid

Purpose: The present study evaluated the influence of the hyaluronic acid (HA) on the bonding ability of self-adhesive resin cements to dentin regarding the bond strength. Eighty bovine incisors were ground flat to obtain a 2-mm thick slices which received conical preparations. The specimens were randomly distributed into 4 groups (n = 15) according to the dentin pretreatment (1 – control: untreated dentin; 2 – application of HA) and the evaluation time (1 – control: immediate evaluation; 2 – hydrolytic degradation: 6 months of storage in water at 37 °C). Preparations received the application of a self-adhesive resin cement (RelyX U200 or MaxCem Elite). Push-out bond strength test was conducted (0.5 mm/min). The bond strength data was submitted to two-way ANOVA/Tukey’s test (α = 0.05). For U200, no significance was observed when comparing the immediate (24 h) and 6 months means for the control groups (unexposed specimens). Previous application of HA to dentin significantly reduced the bond strength of U200 to dentin in both evaluation times (p < 0.05). HA had no significant influence on the push-out bond strength means for the cement MAX in both evaluation times (p > 0.05). The type 1 failure mode (adhesive mode) occurred in 100% of the specimens, irrespective of the dentin treatment or evaluation times. Pretreatment of dentin with HA produces a material-dependent influence on the push-out bond strength. The bonding ability of RelyX U200 is negatively influenced by the pretreatment of dentin with HA, whereas the biomodification of dentin with this bioactive agent causes no impact for the cement MaxCem Elite.