Long-range interaction of radiation-generated self-interstitial atoms and adatoms on tungsten surface

ABSTRACT

The morphological modification of the W surface induced by specimen irradiation with 5?keV He atoms was studied at the atomic level using low-temperature ?eld ion microscope techniques. The major impact-induced damage mode on W {110} surface was found to be the formation of adatom sets produced by radiation-generated self-interstitial atoms emerging at the surface. The long-range interaction was revealed by evaluating the experimental probability density of finding two radiation-generated adatoms at a given separation in comparison with the probability density corresponding to a random distribution of adatoms. The statistically significant difference of these distributions consists of the absence or severe reduction of observed adatom pairs with separations in the range 5–11?Å. The experimental distribution was characterised by a relatively open arrangement of adatoms with the closest separation of about 11?Å. Our field ion microscope observations also reveal the self-organisation of radiation-generated W adatoms into atomic chains with the lateral interatomic separation substantially larger than the nearest-neighbor distance. These effects indicate the existence of long-range interactions between radiation-generated adatoms and radiation-generated self-interstitial atoms in the subsurface region.     

启动子区甲基化导致ZNF331在结直肠癌中表达缺失

通过分析锌指蛋白331 (ZNF331)在结直肠癌中的甲基化及表达情况,探讨ZNF331基因的甲基化与结直肠癌的关系,为结直肠癌的早期诊断和治疗提供新的靶点.采用甲基化特异性PCR(MSP)检测7株结直肠癌细胞系和66例结直肠癌组织标本中ZNF331基因启动子区的甲基化情况.结果7株结直肠癌细胞系中LOVO、RKO、DLD1和HCT116启动子区完全甲基化,SW620和HT29呈部分甲基化,SW480为非甲基化.LOVO、RKO、DLD1、HCT116细胞系中ZNF331mRNA不表达,经5-Aza处理后恢复表达.在SW480、SW620、HT29细胞系中,5-Aza处理前后均表达,处理后表达量增加.在66例结直肠癌组织中,ZNF331启动子区甲基化率为72.7％(48/66),而正常结直肠组织中无甲基化(0/7).     

Neuropsychological assessment with the Visual Gestalt Test: psychometric properties and differential diagnostic probabilities

The Visual Gestalt Test is a neuropsychological instrument developed for evaluation of learning and memory of visuo-spatial material. A revised strategy of scoring has motivated the present study, where data from 153 normal persons, 99 epilepsy patients, and 24 depressed patients are presented and compared. The Visual Gestalt Test is observed to discriminate between normal and diagnosed groups in several ways. Additionally it is found to discriminate between depressed and brain damage subgroups of patients. Data are presented in order to supplement previously published ways of scoring and norms. Practical guidelines for the clinical applications of the test are suggested as perspectives.     

The relationship between prosody and breathing in spontaneous discourse

This article is concerned with the role of prosody in discourse. Three experiments explored the relationship between inspiration, declination, and syntactic boundaries in normal and RHD participants. Fundamental frequency and intensity were measured at the beginning and end of breath units excised from conversational samples. The results revealed evidence of declination of intensity in all samples measured. However, resetting of fundamental frequency was observed only in the samples of normal participants and then only when a breath coincided with the beginning of a sentence. The results suggest that resetting and declination play separate roles in discourse parsing.     

Temporal parameters as cues to phrasal boundaries: a comparison of processing by left- and right-hemisphere brain-damaged individuals

Two experiments were conducted to examine the ability of left- (LHD) and right-hemisphere-damaged (RHD) patients and normal controls to use temporal cues in rendering phrase grouping decisions. The phrase "pink and black and green" was manipulated to signal a boundary after "pink" or after "black" by altering pre-boundary word durations and pause durations at the boundary in a stepwise fashion. Stimuli were presented to listeners auditorily along with a card with three alternative groupings of colored squares from which to select the presented alternative. Results revealed that normal controls were able to use both temporal cues to identify the intended grouping. In contrast, LHD patients required longer than normal pause durations to consistently identify the intended grouping, suggesting a higher than normal threshold for perception of temporal prosodic cues. Surprisingly, the RHD patients exhibited great difficulty with the task, perhaps due to the limited acoustic cues available in the stimuli.     

Effects of Right- and Left-Hemisphere Damage on Understanding Conversational Implicatures

Processing of implicatures was examined in 27 right-brain-damaged (RBD) and 31 left-brain-damaged (LBD) stroke patients with focal lesions using a new implicatures battery (IB) as part of an exploration of the neural basis and modularity of natural language pragmatics. Following Grice, we sampled implicatures of Quantity, Quality, Relation, and Manner. Verbal implicatures consisted of two-sentence conversational vignettes which are literally problematic. Nonverbal implicatures consisted mostly of famous paintings that are literally problematic (e.g., Magritte's "Le Domain d'Arnheim"). The patient has to identify and solve the problem. To compare with performance on the IB, patients also received a Hebrew adaptation of Gardner and Brownell's Right Hemisphere Communication Battery, a new test of basic speech acts (verbal and nonverbal assertions, questions, requests, and commands), a Hebrew version of the Western Aphasia Battery, and standardized neuropsychological tests. Both LBD and RBD patients were significantly impaired in implicature processing relative to age-matched normal controls. In general, both patient groups showed weak correlations of implicatures with extents of lesions in left perisylvian language area or its right-hemisphere (RH) homolog. However, performance of LBD and RBD patients on the IB revealed different patterns of correlations with other pragmatic, language, and nonlanguage tests. In LBD patients, there was a greater association between performance on verbal and nonverbal implicatures and between performance on implicatures and basic speech acts than in RBD patients. Given the different modes in which right-and left-hemisphere (LH) damage affect the processing of conversational implicatures, it remains to be discovered how the two hemispheres interact to process natural language pragmatics in the normal brain in real time.     

Emotional disturbances and their interaction with neuropsychological deficits

The interaction and relationships between neuropsychological tests (which are principally oriented to intellectual and cognitive abilities) and tests of personality and emotional status are complex, but nevertheless important in the clinical assessment of brain-damaged persons. Are indications of emotional disturbances to be expected as a direct consequence of brain damage? If so, how can the indications of emotional disturbances be differentiated from results obtained with psychiatrically disturbed (non-brain-damaged) subjects? Some authors have presumed that emotional disturbances, such as depression, acute anxiety, etc., in their own right cause impaired performances on neuropsychological tests, whereas other authors have proposed that brain damage predisposes the individual to demonstrate evidence of emotional disturbances. If emotional disturbances cause impairment on neuropsychological tests, why is it that so many emotionally disturbed persons without brain damage tend to perform normally on neuropsychological tests? This review of relevant publications considers (1) different general approaches to these questions and their implications for neuropsychology, (2) evidence of differential sensitivity to brain damage of neuropsychological and emotional instruments, (3) the sensitivity and specificity of self-assessments and complaints of head-injured subjects, (4) MMPI findings among head-injured subjects and in interaction with neuropsychological measurements, and (5) principles and guidelines that may be of value in clinical application of findings reported in the literature.     

FROM DNA TO DEAN

Abstract. In this broadly intellectual autobiographical essay, Arthur Peacocke describes how his educational background at Oxford led him eventually to physicochemical studies on DNA and other biological macromolecules and how biological complexity and the general problems it evokes have remained a recurring theme in his thought. He also describes how, although coming from a relatively non ecclesiastical background, this interest has nevertheless been intertwined with the larger questions to which the Christian faith seeks to respond. He outlines how he has been able to reconcile these two strands in his existence-even to becoming a priest-scientist and eventually the Dean of chapel of a Cambridge college. He reflects on the trends in the relation of religion and science over the last four decades and points to some hopeful developments in the relation between the two communities-and to some unanswered questions.     

ADEQUACY OR ORTHODOXY? CHOOSING SIDES AT THE FRONTIER

Abstract. Arthur Peacocke's seminal contribution to the dialogue between science and theology is considered along three dimensions: epistemology, anthropology, and the concept of God. It is suggested that his view of a "hierarchy of disciplines" (1) may not completely characterize the way theology interacts with science, and (2) could limit the creative friction between them. His emphasis on humans as "more than" DNA could result in an anthropology that fails to exploit insights that biology could shed on theological puzzles as the impact of genetics is more widely appreciated. His concept of God may also need to be modified more radically to express our understanding of nature in an age of genetics.     

Partial body weight support treadmill training speed influences paretic and non-paretic leg muscle activation,stride characteristics,and ratings of perceived exertion during acute stroke rehabilitation

BackgroundIntensive task-specific training is promoted as one approach for facilitating neural plastic brain changes and associated motor behavior gains following neurologic injury. Partial body weight support treadmill training (PBWSTT), is one task-specific approach frequently used to improve walking during the acute period of stroke recovery (<1 month post infarct). However, only limited data have been published regarding the relationship between training parameters and physiologic demands during this early recovery phase.ObjectiveTo examine the impact of four walking speeds on stride characteristics, lower extremity muscle demands (both paretic and non-paretic), Borg ratings of perceived exertion (RPE), and blood pressure.DesignA prospective, repeated measures design was used.MethodsTen inpatients post unilateral stroke participated. Following three familiarization sessions, participants engaged in PBWSTT at four predetermined speeds (0.5, 1.0, 1.5 and 2.0 mph) while bilateral electromyographic and stride characteristic data were recorded. RPE was evaluated immediately following each trial.ResultsStride length, cadence, and paretic single limb support increased with faster walking speeds (p ⩽ 0.001), while non-paretic single limb support remained nearly constant. Faster walking resulted in greater peak and mean muscle activation in the paretic medial hamstrings, vastus lateralis and medial gastrocnemius, and non-paretic medial gastrocnemius (p ⩽ 0.001). RPE also was greatest at the fastest compared to two slowest speeds (p < 0.05).ConclusionsDuring the acute phase of stroke recovery, PBWSTT at the fastest speed (2.0 mph) promoted practice of a more optimal gait pattern with greater intensity of effort as evidenced by the longer stride length, increased between-limb symmetry, greater muscle activation, and higher RPE compared to training at the slowest speeds.