怎样做好家居照明

何时开始照明设计？ 当你开始打造一个新家或者重新改造一个家时,便是照明设计的最佳时机,和安装配管系统类似,当整个工程完工后,改变照明配置将是一件花费巨大的事情。     

Relationships between Mitochondrial Function,AMPK, and TORC1 Signaling in Lymphoblasts with Premutation Alleles of the FMR1 Gene

The X-linked FMR1 gene contains a non-coding trinucleotide repeat in its 5’ region that, in normal, healthy individuals contains 20–44 copies. Large expansions of this region (>200 copies) cause fragile X syndrome (FXS), but expansions of 55–199 copies (referred to as premutation alleles) predispose carriers to a neurodegenerative disease called fragile X-associated tremor/ataxia syndrome (FXTAS). The cytopathological mechanisms underlying FXTAS are poorly understood, but abnormalities in mitochondrial function are believed to play a role. We previously reported that lymphoblastoid cell lines (LCLs, or lymphoblasts) of premutation carriers have elevated mitochondrial respiratory activities. In the carriers, especially those not clinically affected with FXTAS, AMP-activated protein kinase (AMPK) activity was shown to be elevated. In the FXTAS patients, however, it was negatively correlated with brain white matter lesions, suggesting a protective role in the molecular mechanisms. Here, we report an enlarged and extended study of mitochondrial function and associated cellular stress-signaling pathways in lymphoblasts isolated from male and female premutation carriers, regardless of their clinical status, and healthy controls. The results confirmed the elevation of AMPK and mitochondrial respiratory activities and reduction in reactive O₂ species (ROS) levels in premutation cells and revealed for the first time that target of rapamycin complex I (TORC1) activities are reduced. Extensive correlation, multiple regression, and principal components analysis revealed the best fitting statistical explanations of these changes in terms of the other variables measured. These suggested which variables might be the most “proximal” regulators of the others in the extensive network of known causal interactions amongst the measured parameters of mitochondrial function and cellular stress signaling. In the resulting model, the premutation alleles activate AMPK and inhibit both TORC1 and ROS production, the reduced TORC1 activity contributes to activation of AMPK and of nonmitochondrial metabolism, and the higher AMPK activity results in elevated catabolic metabolism, mitochondrial respiration, and ATP steady state levels. In addition, the results suggest a separate CGG repeat number-dependent elevation of TORC1 activity that is insufficient to overcome the inhibition of TORC1 in premutation cells but may presage the previously reported activation of TORC1 in FXS cells.     

Room-temperature continuous-wave operation of type-I GaSb-based lasers at 3.1 μm

Type-I interband lasers on GaSb were grown by molecular beam epitaxy using 16 nm InGaAsSb compressively-strained quantum wells (QWs) with 30 nm AlInGaAsSb quinary barriers for improved hole confinement. The 3QW active regions were embedded in standard AlGaAsSb waveguides to limit the thickness of quinary material owing to its low growth temperature requirements. In continuous-wave operation, a typical ridge waveguide laser (width 10 mum, length 1214 mum) produced 6 mW total output power at 20degC with a threshold current of 140 mA. The temperature sensitivity of the devices remains a challenge, as evidenced by the dramatically improved performance at 0degC (16 mW total output power, threshold current 74 mA).     

Computer application of the tracking-function approach to practical stability

A computing algorithm based on the tracking-function method is presented for obtaining regions of practical stability and ultimate boundedness for second-order autonomous differential equations. It is shown that the algorithm obviates certain problems of the tracking-function method as originally formulated. The Van der Pol equation is analysed as an example.     

Effect of hypoxia on the activity and binding of glycolytic and associated enzymes in sea scorpion tissues

The effect of hypoxia on the levels of glycogen, glucose and lactate as well as the activities and binding of glycolytic and associated enzymes to subcellular structures was studied in brain, liver and white muscle of the teleost fish, Scorpaena porcus. Hypoxia exposure decreased glucose levels in liver from 2.53 to 1.70 mumol/g wet weight and in muscle led to its increase from 3.64 to 25.1 mumol/g wet weight. Maximal activities of several enzymes in brain were increased by hypoxia: hexokinase by 23%, phosphoglucoisomerase by 47% and phosphofructokinase (PFK) by 56%. However, activities of other enzymes in brain as well as enzymes in liver and white muscle were largely unchanged or decreased during experimental hypoxia. Glycolytic enzymes in all three tissues were partitioned between soluble and particulate-bound forms. In several cases, the percentage of bound enzymes was reduced during hypoxia; bound aldolase in brain was reduced from 36.4 to 30.3% whereas glucose-6-phosphate dehydrogenase fell from 55.7 to 28.7% bound. In muscle PFK was reduced from 57.4 to 41.7% bound. Oppositely, the proportion of bound aldolase and triosephosphate isomerase increased in hypoxic muscle. Phosphoglucomutase did not appear to occur in a bound form in liver and bound phosphoglucomutase disappeared in muscle during hypoxia exposure. Anoxia exposure also led to the disappearance of bound fructose-1,6-bisphosphatase in liver, whereas a bound fraction of this enzyme appeared in white muscle of anoxic animals. The possible function of reversible binding of glycolytic enzymes to subcellular structures as a regulatory mechanism of carbohydrate metabolism is discussed.     

Constraints on nest site selection: A comparison of predator and flood avoidance in four species of marsh-nesting birds (Genera: Catoptrophorus, Larus, Rallus, and Sterna).

Nest site characteristics associated with flood and predator avoidance were compared for four nonpasserine species of marsh-nesting birds: clapper rails, willets, laughing gulls, and common terns. Species with short nests, willets and terns, minimized flood damage by nesting on higher ground than did gulls and rails that build tall nests. Species with dispersed, cryptic nests had taller surrounding grass than did open-nesting colonial species. Total nest height was similar for species with tall nests and for terns whose short nests were elevated by placement on mats of dead Spartina grass. Willets had lower nest heights than the other species, probably because the inverse relation between grass height and ground height in the salt marsh makes it difficult for willets to find sites with high enough ground for flood avoidance while still retaining high enough grass for nest crypticity. Ground height for common terns and grass height for gulls and rails appear to be cues used in nest site selection. Nests of each species in which these characteristics were maximized were more successful in a major tidal flood. Laughing gulls and clapper rails appear to be more specialized salt marsh nesters than the other two species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gas chromatographic determination of chloramphenicol residues in shrimp: interlaboratory study

An interlaboratory study of a gas chromatographic method for determining chloramphenicol (CAP) residues in shrimp was conducted. An internal standard (Istd), the meta isomer of CAP, was added to the shrimp, and the treated shrimp were homogenized with ethyl acetate. The ethyl acetate extract was defatted with hexane, and the CAP was partitioned into ethyl acetate from an aqueous salt solution. The ethyl acetate was evaporated, and the dried residue was treated with Sylon, a trimethylsilyl derivatizing agent, to yield the trimethylsilyl derivative of CAP. A portion of the solution containing the derivative was injected into a gas chromatograph equipped with an electron capture detector. Levels of fortified and incurred CAP were calculated from the peak area ratio of standard CAP to Istd. Recoveries of CAP from tissue directly fortified at 5 ppb were 102% (within-laboratory relative standard deviation [RSDr] = 5.6%), 104% (RSDr = 5.5%), and 108% (RSDr = 6.3%) from Laboratories 1, 2, and 3, respectively. Incurred-CAP residues at 5 and 10 ppb levels were also determined, with the following results: Laboratory 1: composite A, 4.56 ppb (RSDr = 14.0%); composite B, 8.38 ppb (RSDr = 11.6%); Laboratory 2: composite A, 4.17 ppb (RSDr = 12.5%); composite B, 8.90 ppb (RSDr = 5.60%); Laboratory 3: composite A, 4.66 ppb (RSDr = 14.9%); composite B, 11.0 ppb (RSDr = 11.8%).     

Role of antioxidant defenses in the tolerance of severe dehydration by anurans. The case of the leopard frog Rana pipiens

Protein tyrosine phosphatases (PTPs) play a critical role in regulating insulin action in part through dephosphorylation of the active (autophosphorylated) form of the insulin receptor (IRK) and attenuation of its tyrosine kinase activity. Following insulin binding the activated IRK is rapidly internalized into the endosomal apparatus, a major site at which the IRK is dephosphorylated in vivo. Studies in rat liver suggest a complex regulatory process whereby PTPs may act, via selective IRK tyrosine dephosphorylation, to modulate IRK activity in both a positive and negative manner. Use of peroxovanadium (pV) compounds, shown to be powerful PTP inhibitors, has been critical in delineating a close relationship between the IRK and its associated PTP(s) in vivo. Indeed the in vivo administration of pV compounds effected activation of IRK in parallel with an inhibition of IRK-associated PTP activity. This process was accompanied by a lowering of blood glucose levels in both normal and diabetic rats thus implicating the IRK-associated PTP(s) as a suitable target for defining a novel class of insulin mimetic agents. Identification of the physiologically relevant IRK-associated PTP(s) should facilitate the development of drugs suitable for managing diabetes mellitus.