1,189 research outputs found
Altered pituitary hormone secretion in male rats exposed to Bisphenol A
Bisphenol A (BPA) is a xenobiotic estrogenic compound. This compound has been suspected to have estrogenic effects on reproductive system of males and females. In this present study we investigated possible low-dose effects of BPAon Luteinizing Hormone in rats. Male Wistar rats (12-13 weeks old) were administrated a daily intra peritoneal 10 μg/kgbw/day, 50 μg/kgbw/day, 100 μg/kgbw/ day dose of BPA for 6, 6, and 12 days, and one day after last injection, serum level of Luteinizing Hormone was examined by ELISA method. All data were expressed as means ± SE. Two-way ANOVA was performed. Analysis of data showed that in all dose groups, plasma level of Luteinizing Hormone significantly decreased compared to control group. The present study showed that BPA at low doses affects Luteinizing Hormone, one of main hormones in spermatogenesis in the adult Wistar rats, and subsequently alters the steroidgenesis in testicular Leydig cells
Physiological responses of two rice (Oryza sativa L.) genotypes to chilling stress at seedling stage
In this study, quantitative changes of dry matter, proline and total soluble protein in shoot and root, stomatal conductance (gs), total chlorophyll, chlorophyll stability index (CSI) and soil and plant analyzer development (SPAD) number of latest fully-expanded leaves were determined in an Iranian coldsensitive rice genotype (Hoveizeh) in comparison to an international check genotype (IRCTN34, coldtolerant). The hydroponic experiment was arranged in a completely randomized design with three replications under the growth chamber condition under a controlled environment of 29/22°C (day/night) and 12 h light photoperiod. Then, the treatment plants were exposed to 15/10°C (day/night) cold stress for two weeks and control plants were kept at 29/22°C (day/night). Dry matter accumulation decreased with chilling stress in the two genotypes, with decreases been more pronounced in Hoveizeh genotype. Our results showed that cold treatment increased accumulation of total soluble protein (only in coldtolerant genotype) and proline in rice seedlings, while it decreased the content of chlorophyll, stomatal conductance, total soluble protein (only in cold-sensitive genotype) and dry matter. The results indicated that higher contents of protein and chlorophyll under stress were associated with tolerance to chilling.Key words: Abiotic stress, cold, total soluble protein, proline, total chlorophyll, stomatal conductance
Zinc Deficiency Leads to Lipid Changes in Drosophila Brain Similar to Cognitive-Impairing Drugs: An Imaging Mass Spectrometry Study
Several diseases and disorders have been suggested to be associated with zinc deficiency, especially learning and memory impairment. To have better understanding about the connection between lipid changes and cognitive impairments, we investigated the effects of a zinc-chelated diet on certain brain lipids ofDrosophila melanogasterby using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The data revealed that there are increases in the levels of phosphatidylcholine and phosphatidylinositol in the central brains of the zinc-deficient flies compared to the control flies. In contrast, the abundance of phosphatidylethanolamine in the brains of the zinc-deficient flies is lower. These data are consistent with that of cognitive-diminishing drugs, thus providing insight into the biological and molecular effects of zinc deficiency on the major brain lipids and opening a new treatment target for cognitive deficit in zinc deficiency
Height Fluctuations and Intermittency of Films by Atomic Force Microscopy
The spatial scaling law and intermittency of the surface roughness
by atomic force microscopy has been investigated. The intermittency of the
height fluctuations has been checked by two different methods, first, by
measuring scaling exponent of q-th moment of height-difference fluctuations
i.e. and the second, by defining generating
function and generalized multi-fractal dimension . These methods
predict that there is no intermittency in the height fluctuations. The observed
roughness and dynamical exponents can be explained by the numerical simulation
on the basis of forced Kuramoto-Sivashinsky equation.Comment: 6 pages (two columns), 11 eps. figures, late
Robust orthogonal parameterization of evolution strategy for adaptive laser pulse shaping
Many spectroscopic applications of femtosecond laser pulses require properly-shaped spectral phase profiles. The optimal phase profile can be programmed on the pulse by adaptive pulse shaping. A promising optimization algorithm for such adaptive experiments is evolution strategy (ES). Here, we report a four fold increase in the rate of convergence and ten percent increase in the final yield of the optimization, compared to the direct parameterization approach, by using a new version of ES in combination with Legendre polynomials and frequency-resolved detection. Such a fast learning rate is of paramount importance in spectroscopy for reducing the artifacts of laser drift, optical degradation, and precipitation
Structure-Sensitive Mechanism of Nanographene Failure
The response of a nanographene sheet to external stresses is considered in
terms of a mechanochemical reaction. The quantum chemical realization of the
approach is based on a coordinate-of-reaction concept for the purpose of
introducing a mechanochemical internal coordinate (MIC) that specifies a
deformational mode. The related force of response is calculated as the energy
gradient along the MIC, while the atomic configuration is optimized over all of
the other coordinates under the MIC constant-pitch elongation. The approach is
applied to the benzene molecule and (5, 5) nanographene. A drastic anisotropy
in the microscopic behavior of both objects under elongation along a MIC has
been observed when the MIC is oriented either along or normally to the C-C
bonds chain. Both the anisotropy and high stiffness of the nanographene
originate at the response of the benzenoid unit to stress.Comment: 19 pages, 7 figures 1 tabl
A Survey on Continuous Time Computations
We provide an overview of theories of continuous time computation. These
theories allow us to understand both the hardness of questions related to
continuous time dynamical systems and the computational power of continuous
time analog models. We survey the existing models, summarizing results, and
point to relevant references in the literature
Solving analytic differential equations in polynomial time over unbounded domains
In this paper we consider the computational complexity of solving initial-value problems de ned with analytic ordinary diferential
equations (ODEs) over unbounded domains of Rn and Cn, under the Computable Analysis setting. We show that the solution can be computed in polynomial time over its maximal interval of de nition, provided it satis es a very generous bound on its growth, and that the function admits an analytic extension to the complex plane
The general purpose analog computer and computable analysis are two equivalent paradigms of analog computation
In this paper we revisit one of the rst models of analog
computation, Shannon's General Purpose Analog Computer (GPAC).
The GPAC has often been argued to be weaker than computable analysis.
As main contribution, we show that if we change the notion of GPACcomputability
in a natural way, we compute exactly all real computable
functions (in the sense of computable analysis). Moreover, since GPACs
are equivalent to systems of polynomial di erential equations then we
show that all real computable functions can be de ned by such models
Utility of Geostationary Lightning Mapper-derived lightning NO emission estimates in air quality modeling studies
Lightning is one of the primary natural sources of nitric oxide (NO), and the influence of lightning-induced NO (LNO) emission on air quality has been investigated in the past few decades. In the current study an LNO emissions model, which derives LNO emission estimates from satellite-observed lightning optical energy, is introduced. The estimated LNO emission is employed in an air quality modeling system to investigate the potential influence of LNO on tropospheric ozone. Results show that lightning produced 0.174 Tg N of nitrogen oxides (NOx = NO + NO2) over the contiguous US (CONUS) domain between June and September 2019, which accounts for 11.4 % of the total NOx emission. In August 2019, LNO emission increased ozone concentration within the troposphere by an average of 1 %–2 % (or 0.3–1.5 ppbv), depending on the altitude; the enhancement is maximum at ∼ 4 km above ground level and minimum near the surface. The southeastern US has the most significant ground-level ozone increase, with up to 1 ppbv (or 2 % of the mean observed value) difference for the maximum daily 8 h average (MDA8) ozone. These numbers are near the lower bound of the uncertainty range given in previous studies. The decreasing trend in anthropogenic NOx emissions over the past 2 decades increases the relative contribution of LNO emissions to total NOx emissions, suggesting that the LNO production rate used in this study may need to be increased. Corrections for the sensor flash detection efficiency may also be helpful. Moreover, the episodic impact of LNO on tropospheric ozone can be considerable. Performing backward trajectory analyses revealed two main reasons for significant ozone increases: long-distance chemical transport and lightning activity in the upwind direction shortly before the event.</p
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