Motor planning: effect of directional uncertainty with continuous spatial cues

We have investigated the effect of directional uncertainty on the planning of reaching movements. For this purpose, we have used sections of annuli as spatial cues to indicate the directional range within which the target would be presented. The results showed that the reaction time of the reaching response increased with cue range and with the angle between the center of the cue and the target. In addition, the initial direction of movement was biased toward the center of the cue. These results conformed to the predictions of the capacity-sharing model. This model assumes that the processing resources used for motor planning are limited and distributed as a function of the range of directions indicated by the cue, and that when the target appears, these resources are reallocated to represent the response to be executed.     

Plasma levels of soluble transferrin receptors and Clara cell protein (CC16) during bipolar mania and subsequent remission

Clara cell protein (CC16) and transferrin receptor (TfR) have been reported as possible biological markers for major depression and schizophrenia. However, the alternations of plasma TfR and CC16 levels and the influences of numerous clinical variables on them during bipolar mania are not sufficiently described. We investigated the immune function of 36 bipolar I, manic (DSM-IV) patients with Young Mania Rating Scale (YMRS) scores > or =26 as well as during the subsequent remission (YMRS < or =12) and age- and sex- matched healthy controls. The plasma TfR levels were increased during acute mania along with subsequent remission and were independent of medication status, individual variations, clinical and erythrocyte variables. Among inflammatory parameters and haematological variables, the plasma TfR levels merely had significant and negative relationship with the percentage of monocyte in circulating leukocyte counts despite of elevated plasma soluble interleukin-2 receptors levels during bipolar mania. The plasma levels of CC16 of bipolar patients did not significantly alter during acute mania, whereas smoking, body mass index, and co-existing psychotic features collectively contributed 42% of the plasma levels of CC16. We provide additional evidence to indicate the pathophysiological role of the immune systems in affective disorders. It is suggested that the elevation of plasma TfR levels might be a trait phenomenon in bipolar disorder.     

Chain Connectivity and Conformational Variability of Polymers: Clues to an Adequate Thermodynamic Description of Their Solutions, 1

This is the first of two parts investigating the Flory‐Huggins interaction parameter, χ, as a function of composition and chain length. Part 1 encompasses experimental and theoretical work. The former comprises the synthesis of poly(dimethylsiloxane)s with different molar mass and the measurements of their second osmotic virial coefficients, A₂, in solvents of diverse quality as a function of M via light scattering and osmotic pressures. The theoretical analysis is performed by subdividing the dilution process into two clearly separable steps. It yields the following expression for χ_o, the χ value in range of pair interaction: χ_o = α ? ζ λ. The parameter α measures the effect of contact formation between solvent molecules and polymer segments at fixed chain conformation, whereas the parameter ζ quantifies the contributions of the conformational changes taking place in response to dilution; ζ becomes zero for theta conditions. The influences of M are exclusively contained in the parameter λ The new relation is capable of describing hitherto incomprehensible experimental findings, like a diminution of χ_o with rising M. The evaluation of experimental information for different systems according to the established equation displays the existence of a linear interrelation between ζ and α. Part 2 of this investigation presents the generalization of the present approach to solutions of arbitrary composition and discusses the physical meaning of the parameters in more detail.

Conformational response, ζ, as a function of α, the interaction parameter for fixed conformation.     

Using n-gram method in the decomposition of compound medical diagnoses

Objective: Our goal in this study was to find an easy to implement method to detect compound medical diagnosis in Hungarian medical language and decompose them into expressions referring to a single disease. Methods: A corpus of clinical diagnoses extracted form discharge reports (3079 expressions, each of them referring to only one disease) was represented in an n-gram tree (a series of n consecutive word). A matching algorithm was implemented in a software, which is able to identify sensible n-grams existing both in test expressions and in the n-gram tree. A test sample of another 92 diagnoses was decomposed by two independent humans and by the software. The decompositions were compared with measure the recall and the precision of the method. Results: There was not full agreement between the decompositions of the humans, (which underlines the relevance of the problem). A consensus was arrived in all disagreed point by a third opinion and open discussion. The resulting decomposition was used as a gold standard and compared with the decomposition produced by the computer. The recall was 82.6% the precision 37.2%. After correction of spelling errors in the test sample the recall increased to 88.6% while the precision slightly decreased to 36.7%. Conclusion: The proposed method seems to be useful in decomposition of compound diagnostic expressions and can improve quality of diagnostic coding of clinical cases. Other statistical methods (like vector space methods or neural networks) usually offer a ranked list of candidate codes either for single or compound expressions, and do not warn the user how many codes should be chosen. We propose our method especially in a situation where formal NLP techniques are not available, as it is the case with scarcely spoken languages like Hungarian.     

The effects of frequency in pallidal deep brain stimulation for primary dystonia

Abstract. The effect of stimulation frequency for pallidal deep brain stimulation in five patients with either generalized or segmental dystonia was evaluated three to twelve months postoperatively via a randomized, double-blind paradigm. The quality of life and the severity of dystonic symptoms improved by approximately 60% and 43% respectively using a frequency of 130 Hz. Compared with 130 Hz a significant further clinical improvement was observed at frequencies of 180 and 250 Hz, which contrasted with a significant deterioration at lower frequencies (5, 50 Hz) compared to 130 Hz.     

Initial in vivo experience with steady-state subzone-based MR elastography of the human breast

PURPOSE: To describe initial in vivo experiences with a subzone-based, steady-state MR elastography (MRE) method. This sparse collection of in vivo results is intended to shed light on some of the strengths and weaknesses of existing clinical MRE approaches and to indicate important areas of future research. MATERIALS AND METHODS: Elastic property reconstruction results are compared with data compiled from the limited existing body of published studies in breast elasticity. Mechanical parameter distributions are also investigated in terms of their implications for the nature of biological soft tissue. Additionally, a derivation of the statistical variance of the elastic parameter reconstruction is given and the resulting confidence intervals (CIs) for different parameter solutions are examined. RESULTS: By comparison with existing estimates of the elastic properties of breast tissue, the subzone-based, steady-state MRE method is seen to produce reasonable estimates for the mechanical properties of in vivo tissue. CONCLUSION: MRE shows potential as an effective way to determine the elastic properties of breast tissue, and may be of significant clinical interest.     

Face processing in 8-month-old infants: evidence for configural and analytical processing

Two experiments examined whether 8-month-old infants process faces (photos in Experiment 1, schematic faces in Experiment 2) analytically by processing facial features independently of the facial context or configurally by processing the features in conjunction with the facial context. Infants were habituated to two faces and looking time was measured. After habituation they were tested with a habituation face, a switch face, or a novel face. In the switch faces, single features of the habituation faces were switched. The results showed that the infants processed facial features of photographs of faces configurally whereas they processed features of schematic faces (eyes, nose, facial contour) analytically. Thus, although infants have access to both processing modes, for real looking faces they use the configural mode.     

Evaluation of primary human liver cells in bioreactor cultures for extracorporeal liver support on the basis of urea production

Primary human liver cells from donor organs unsuitable for transplantation were cultivated in bioreactors developed for extracorporeal liver support. Because each system contains cells originating from an individual organ, each bioreactor culture must be individually characterized. The objective of this study was to identify suitable decisive parameters for the evaluation of cell culture performance. We analyzed the data from 47 bioreactor cultures containing 437 +/- 110 g of cells. Choosing urea production as the decisive parameter, the bioreactor cultures were divided into high-performance (daily urea production > or = 110 mg per bioreactor between culture days 3 and 14) and low-performance cultures. Comparing the mean courses of the groups revealed a significant distinction in most other investigated biochemical parameters. In conclusion, urea production seems to be an appropriate parameter for evaluating the performance of liver cell cultures in bioreactors because it corresponds to all other evaluated parameters of cell function.     

Centralizing the non-central chi-square: A new method to correct for population stratification in genetic case-control association studies

We present a new method, the delta-centralization (DC) method, to correct for population stratification (PS) in case-control association studies. DC works well even when there is a lot of confounding due to PS. The latter causes overdispersion in the usual chi-square statistics which then have non-central chi-square distributions. Other methods approach the noncentrality indirectly, but we deal with it directly, by estimating the non-centrality parameter tau itself. Specifically: (1) We define a quantity delta, a function of the relevant subpopulation parameters. We show that, for relatively large samples, delta exactly predicts the elevation of the false positive rate due to PS, when there is no true association between marker genotype and disease. (This quantity delta is quite different from Wright's F(ST) and can be large even when F(ST) is small.) (2) We show how to estimate delta, using a panel of unlinked "neutral" loci. (3) We then show that delta2 corresponds to tau the noncentrality parameter of the chi-square distribution. Thus, we can centralize the chi-square using our estimate of 6; this is the DC method. (4) We demonstrate, via computer simulations, that DC works well with as few as 25-30 unlinked markers, where the markers are chosen to have allele frequencies reasonably close (within +/- .1) to those at the test locus. (5) We compare DC with genomic control and show that where as the latter becomes overconservative when there is considerable confounding due to PS (i.e. when delta is large), DC performs well for all values of delta.