结构函数的标度律

分析了GOY模型结构函数的标度律．指出结构函数的振荡涨落导致非线性标度律。     

Mandibular Function and Biomechanical Stress and Scaling

Patterns of stress were analyzed in the mandibular symphysisof Macaca fascicularis using rosette strain gages. During jawopening, the mandibular symphysis is bent due to medial transversebending of the mandibular corpora. Levels of stress and strainare relatively low at this time, and the source of this stressis the medially-directed component of force from the lateralpterygoid muscles. During the power stroke of mastication, thesymphysis is maximally stressed. At this time the symphysisexperiences dorsoventral shear and bending due to lateral transversebending of the mandibular corpora, i.e., "wishboning." The dorsoventralshear is due to the vertical component of the balancingsideadductor muscle force; the "wishboning" is due to the laterally-directedcomponents of the bite and jaw adductor muscle forces. Unlikedorsoventral shear, "wishboning" results in considerable levelsof stress and strain, particularly along the most lingual aspectof the symphysis. The most effective way to counter this stressis to increase the thickness of the symphysis in the labio-lingualdirection. The stress analysis and an allometric analysis ofmandibular dimensions in female cercopithecine (Old World) monkeysindicates that allometric changes in the symphysis are readilyunderstood if the mandible is modelled as a curved beam. Withincreasing body size, symphyseal thickness in cercopithecinesmust increase in a positively allometric fashion so as to preventthe occurrence of dangerously high levels of stress along themost lingual aspect of the symphysis. This is because increasingbody size is associated with three factors thathave importantconsequences within the context of the biomechanics of curvedbeams: (1) jaw length is positively allometric to body size,(2) mandibular-arch width is negatively allometric to body size,and (3) there is a tendency to use relatively greater amountsof balancing-side jaw muscle force with increased body sizebecause of dietary changes and allometricconstraints on totaljaw muscle force.     

An Unconventional Copper Protein Required for Cytochrome c Oxidase Respiratory Function under Extreme Acidic Conditions

Very little is known about the processes used by acidophile organisms to preserve stability and function of respiratory pathways. Here, we reveal a potential strategy of these organisms for protecting and keeping functional key enzymes under extreme conditions. Using Acidithiobacillus ferrooxidans, we have identified a protein belonging to a new cupredoxin subfamily, AcoP, for “acidophile CcO partner,” which is required for the cytochrome c oxidase (CcO) function. We show that it is a multifunctional copper protein with at least two roles as follows: (i) as a chaperone-like protein involved in the protection of the Cu_A center of the CcO complex and (ii) as a linker between the periplasmic cytochrome c and the inner membrane cytochrome c oxidase. It could represent an interesting model for investigating the multifunctionality of proteins known to be crucial in pathways of energy metabolism.     

The Gustatory Neural Response Function

With few exceptions, afferent neurons in the various sensory systems respond to wide ranges of stimuli. In those sensory systems for which the stimulus dimensions are understood, the response functions of these neurons may be described; they are usually simple functions with one maximum, although many variations exist. In the chemical senses, the stimulus dimensions are not known, and thus the neural response functions of these neurons have never been described. The present paper presents methods to determine these response functions and the stimulus dimensions for the chemical senses. A tentative response function for taste is developed, and preliminary steps are taken toward disclosing the stimulus dimensions.     

Anger under Control: Neural Correlates of Frustration as a Function of Trait Aggression

Antisocial behavior and aggression are prominent symptoms in several psychiatric disorders including antisocial personality disorder. An established precursor to aggression is a frustrating event, which can elicit anger or exasperation, thereby prompting aggressive responses. While some studies have investigated the neural correlates of frustration and aggression, examination of their relation to trait aggression in healthy populations are rare. Based on a screening of 550 males, we formed two extreme groups, one including individuals reporting high (n=21) and one reporting low (n=18) trait aggression. Using functional magnetic resonance imaging (fMRI) at 3T, all participants were put through a frustration task comprising unsolvable anagrams of German nouns. Despite similar behavioral performance, males with high trait aggression reported higher ratings of negative affect and anger after the frustration task. Moreover, they showed relatively decreased activation in the frontal brain regions and the dorsal anterior cingulate cortex (dACC) as well as relatively less amygdala activation in response to frustration. Our findings indicate distinct frontal and limbic processing mechanisms following frustration modulated by trait aggression. In response to a frustrating event, HA individuals show some of the personality characteristics and neural processing patterns observed in abnormally aggressive populations. Highlighting the impact of aggressive traits on the behavioral and neural responses to frustration in non-psychiatric extreme groups can facilitate further characterization of neural dysfunctions underlying psychiatric disorders that involve abnormal frustration processing and aggression.     

Glial Contributions to Neural Function and Disease

The nervous system consists of neurons and glial cells. Neurons generate and propagate electrical and chemical signals, whereas glia function mainly to modulate neuron function and signaling. Just as there are many different kinds of neurons with different roles, there are also many types of glia that perform diverse functions. For example, glia make myelin; modulate synapse formation, function, and elimination; regulate blood flow and metabolism; and maintain ionic and water homeostasis to name only a few. Although proteomic approaches have been used extensively to understand neurons, the same cannot be said for glia. Importantly, like neurons, glial cells have unique protein compositions that reflect their diverse functions, and these compositions can change depending on activity or disease. Here, I discuss the major classes and functions of glial cells in the central and peripheral nervous systems. I describe proteomic approaches that have been used to investigate glial cell function and composition and the experimental limitations faced by investigators working with glia.The nervous system is composed of neurons and glial cells that function together to create complex behaviors. Traditionally, glia have been considered to be merely passive contributors to brain function, resulting in a pronounced neurocentric bias among neuroscientists. Some of this bias reflects a paucity of knowledge and tools available to study glia. However, this view is rapidly changing as new tools, model systems (culture and genetic), and technologies have permitted investigators to show that glia actively sculpt and modulate neuronal properties and functions in many ways. Glia have been thought to outnumber neurons by 10:1, although more recent studies suggest the ratio in the human brain is closer to 1:1 with region-specific differences (1). There are many different types of glia, some of which are specific to the central nervous system (CNS),¹ whereas others are found only in the peripheral nervous system (PNS). The main types of CNS glia include astrocytes, oligodendrocytes, ependymal cells, radial glia, and microglia. In the PNS, the main glial cells are Schwann cells, satellite cells, and enteric glia. These cells differ and are classified according to their morphologies, distinct anatomical locations in the nervous system, functions, developmental origins, and unique molecular compositions. Among the different classes of glia there are additional subclasses that reflect further degrees of specialization. In this review, I will discuss the characteristics and functions of the major glial cell types including astrocytes, microglia, and the myelin-forming oligodendrocytes (CNS) and Schwann cells (PNS). Because of space limitations, it is impossible to give a complete accounting of all glia and what is known about each of these cell types. Therefore, I encourage the interested reader to refer to some of the many excellent reviews referenced below that focus on individual glial cell types. Finally, I will discuss proteomic studies of glial cell function and some of the unique challenges investigators face when working with these cells.     

Features of Human Metabolic Reactions under Extreme Cold Exposure

We measured 45 biochemical indices of blood serum samples in six volunteers aged 23–35 years before and after 3-min exposure to air cryosauna at a temperature of–70°С. We observed an increase in the activity of glutamate dehydrogenase (by a factor of 3.4), aspartate aminotransferase (by 46%), lipase (52%), lactate dehydrogenase (16%), cholinesterase (18%), leucin aminopeptidase (12%), and prostatic acid phosphatase (45%). Moreover, we observed an increase in the level of free fatty acids (by a factor of 2.8), HDLcholesterol (by 10%), creatinine (21%), glucose and ß-hydroxybutirate (11%), high-sensitivity C-reactive protein (12%), potassium (14%), and chlorides (7%). In contrast, atherogenic index values decreased by 14% compared with background level. Most of changes in biochemical blood parameters mentioned above remained almost constant within 20, 60, and 180 min after 3 min of cryosauna; the values did not reach their initial levels. It is concluded that urgent adaptation of human body to low temperatures is associated with increased intensification of reactions in the respiratory chain of mitochondria, an increase in the rate of metabolic reactions due to the elevated production of energy substances resulting from activation of lipolysis and glycolysis.     

The Growth of Scions under Conditions of Extreme Vigour

In order to ascertain growth-rates of scions free from rootstocklimitations, shoot- and root-scions were induced to grow veryrapidly by grafting them on to heavily pruned rootstocks. Underthese conditions the growth-rates of shoot-scions did not followthe same order as the root-scions of the same varieties; thegrowth-rates of root and shoot scions relative to one anotherwere in accordance with the hypothesis that the growth-rateof a composite tree wan the resultant of the growth-rates ofits component varieties. Varietali differences in shoot weightwere attributable largely to differences in the proportion ofleafage on the shoots, average increments in shoot weight pergram of leaf being nearly the aame for all varieties; withinvarieties, the lighter shoots had less increment per gram ofleaf than the heavier, despite, in some cases, a higher proportionof leafage.     

Preserving biodiversity under current and future climates: a case study

Aim The conservation of biological and genetic diversity is a major goal of reserve systems at local, regional, and national levels. The International Union for the Conservation of Nature and Natural Resources suggests a 12% threshold (area basis) for adequate protection of biological and genetic diversity of a plant community. However, thresholds based on area may protect only a small portion of the total diversity if the locations are chosen without regard to the variation within the community. The objectives of this study were to demonstrate methods to apply a coarse‐filter approach for identifying gaps in the current reserve system of the Psuedotsuga menziesii (Douglas‐fir) forest type group based on current climatic conditions and a global climate change scenario. Location Western United States. Method We used an ecological envelope approach that was based on seven bioclimatic factors, two topographic factors, and two edaphic factors. Multivariate factor analysis was then used to reduce the envelope to two dimensions. The relative density of habitat and protected areas were identified in each part of the envelope based on the current climate and potential future climate. We used this information to identify gaps in the reserve system. Results Although the protected areas occurred in all parts of the envelope, most existed in colder and drier areas. This was true for both the current climate and potential future climate. Main conclusion To protect more of the ecological envelope, future conservation efforts would be most effective in western Oregon, north‐western Washington, and north‐western California.     

Aerobic Biodegradation of Liquid Motor Fuels under Extreme Acidic Conditions

Microbiology - Biodegradation of liquid petroleum motor fuels and fuel mixtures containing biodiesel fuel (methyl ethers of rapeseed fatty acids) by aerobic acidophilic actinobacteria Mycobacterium...     

梗阻性低位直肠癌保肛手术可行性探讨

目的:探讨梗阻性低位直肠癌保肛治疗(直肠癌前切除术(dixon手术))的可行性及术后肠瘘的防治。方法:回顾性分析我科2009年1月-2012年1月梗阻性低位直肠癌的保肛治疗(dixon)24例手术患者(梗阻性保肛组)临床资料及非梗阻性低位直肠癌保肛治疗(dixon)的24例患者(非梗阻性保肛组)临床资料,比较梗阻性与非梗阻性低位肠梗阻保肛治疗的临床疗效,分析梗阻性低位肠梗阻保肛治疗的可行性。结果:梗阻性保肛组住院天数:11.9天,非梗阻性肠梗阻保肛组8.7天P0.05;梗阻性保肛组发生肠瘘:4例(16.7%),非梗阻性肠梗阻保肛组发生肠瘘:1例(4.2%)P0.05,经充分引流后肠瘘愈合,无1人死亡,两组术后至出院期间死亡人数:0例;梗阻性保肛组肠功能恢复(以排气排便为指标):5.1天,非梗阻性保肛组肠功能恢复:3.8天,P0.05;术后6个月腹泻便秘患者两组相同为24人;术后6个月梗阻性保肛组肿瘤复发6人(25%),非梗阻性保肛组肿瘤复发5人(20.8%),P0.05。结论:梗阻性低位肠梗阻保肛治疗住院期疗效较非梗阻性保肛组差,中远期疗效无明显差异。梗阻性低位直肠癌可行保肛治疗。     

梗阻性低位直肠癌保肛手术可行性探讨

目的：探讨梗阻性低位直肠癌保肛治疗（直肠癌前切除术（dixon手术））的可行性及术后肠瘘的防治。方法：回顾性分析我科2009年1月．2012年1月梗阻性低位直肠癌的保肛治疗（dixon）24例手术患者（梗阻性保肛组）临床资料及非梗阻性低位直肠癌保肛治疗（dixon）的24例患者（非梗阻性保肛组）临床资料,比较梗阻性与非梗阻性低位肠梗阻保肛治疗的临床疗效,分析梗阻性低位肠梗阻保肛治疗的可行性。结果：梗阻性保肛组住院天数：11．9天,非梗阻性肠梗阻保肛组8．7天P〈0．05;梗阻性保肛纽发生肠瘘：4例（16．7％）,非梗阻性肠梗阻保肛组发生肠瘘：1例（4.2％）P〈0．05,经充分引流后肠痿愈合,无1人死亡,两组术后至出院期间死亡人数：0例;梗阻性保肛组肠功能恢复（以排气排便为指标）：5．1天,非梗阻性保肛组肠功能恢复：3．8天,P〈0．05;术后6个月腹泻便秘患者两组相同为24人;术后6个月梗阻性保肛组肿瘤复发6人（25％）,非梗阻性保肛组肿瘤复发5人（20．8％）,P〉0．05。结论：梗阻性低位肠梗阻保肛治疗住院期疗效较非梗阻性保肛组差,中远期疗效无明显差异。梗阻性低位直肠癌可行保肛治疗。     

Survival of Microorganisms under the Extreme Conditions of the Atacama Desert

Spores of Bacillus subtilis, conidia of Aspergillus niger, versicolor and ochraceus andcells of Deinococcus radiodurans have been exposed in the dark at two locations (at about 23°S and 24°S) in the Atacama Desert for up to 15 months. B. subtilis spores (survival 15%) and A. niger conidia (survival 30%) outlived the other species. The survival of the conidiaand spores species was only slightly poorer than that of thecorresponding laboratory controls. However, the Deinococcus radiodurans cells did not survive the desertexposure, because they are readily inactivated at relativehumidities between 40 and 80% which typically occurduring desert nights. Cellular monolayers of the dry sporesand conidia have in addition been exposed to the full sunlight for up to several hours. The solar fluences causing 63% loss in viability (F₃₇-values) have been determined.These F₃₇-values are compared with those determined atother global locations such as Punta Arenas (53°S), Key Largo (25°N) or Mainz (50°N) during the same season. Thesolar UVB radiation kills even the most resistantmicroorganisms within a few hours due to DNA damages. Thedata are also discussed with respect to possible similaritiesbetween the climatic conditions of the recent Atacama Desertand the deserts of early Mars.     

Conditionally Immortalized Neural Cell Lines: Potential Models for the Study of Neural Cell Function

Studies on primary cell cultures have contributed significantly to our understanding of neural cell function. Nevertheless, for many studies the value of these primary cell cultures has been limited by the time the cultures survivein vitro,the quantity of cellular material available for analysis, and the need to prepare the cells on a regular basis from fresh tissue. Techniques for immortalizing cells have existed for some time, but the repertoire of immortalizing genes has grown significantly. This has expanded our ability to generate useful cell lines of specific neural types that are better models of thein vivophenotype than previously. The constitutive expression of oncogenes keeps cells in a proliferative state that could lead to the loss of differentiated gene expression and function. An appealing improvement of immortalization methodology is the use of temperature-sensitive oncogenes that generate cell lines that can proliferate at a permissive temperature and “differentiate” at a nonpermissive temperature. The proliferation of such conditionally immortalized cell lines can be suppressed simply by increasing the temperature. Cell lines maintained at the nonpermissive temperature can enter into a stage in which they express differentiated properties of the cell. The potential ability of conditionally immortalized neural cell lines to accurately reflect theirin vivofunction has now been demonstrated on several occasions through transplantation experiments. In this report, the generation of these cell lines is described along with a discussion of their potential applications in neurobiology.     

Scaling of the mean and variance of population dynamics under fluctuating regimes

Theoretical ecologists have long sought to understand how the persistence of populations depends on the interactions between exogenous (biotic and abiotic) and endogenous (e.g., demographic and genetic) drivers of population dynamics. Recent work focuses on the autocorrelation structure of environmental perturbations and its effects on the persistence of populations. Accurate estimation of extinction times and especially determination of the mechanisms affecting extinction times is important for biodiversity conservation. Here we examine the interaction between environmental fluctuations and the scaling effect of the mean population size with its variance. We investigate how interactions between environmental and demographic stochasticity can affect the mean time to extinction, change optimal patch size dynamics, and how it can alter the often-assumed linear relationship between the census size and the effective population size. The importance of the correlation between environmental and demographic variation depends on the relative importance of the two types of variation. We found the correlation to be important when the two types of variation were approximately equal; however, the importance of the correlation diminishes as one source of variation dominates. The implications of these findings are discussed from a conservation and eco-evolutionary point of view.     

Preserving the Pascagoula

Wetlands Ecology and Management -