A Perturbation Expansion Method to Study Highly Correlated Spins

This paper proposes a new numerical algorithm to study dynamical spin dependent properties of local highly correlated structures. The method consists in diagonalizing a finite cluster containing the many-body terms of the Hamiltonian and embedding it into the rest of the system, the Embedding Cluster Approximation (ECA), combined with Wilson’s ideas of logarithmic discretization of the representation of the Hamiltonian, the Logarithm Discretization Embedded Cluster Approximation (LDECA). The physics associated to a dot and a side-coupled double dot connected to leads are discussed in detail.     

Mechanisms for the acquisition of situation awareness in situated agents

Situation awareness (SA) is the understanding required to operate a complex system in a highly dynamic environment. We evaluate theories of individual SA and the processes by which individuals maintain their understanding of a situation. We support a situated approach, which holds that individual operators make use of limited internal representation, and rely extensively on interactions with external props and tools to achieve and maintain SA. We also propose a synthesis of Durso et al. (2007) [Durso, F., Rawson, K., and Girotto, S., 2007. Comprehension and situation awareness. In: F. Durso, et al., eds. Handbook of applied cognition. 2nd ed. Hoboken, NJ: Wiley, 163–194.] Construction-Integration model of scene analysis with Sperber and Wilson's (1995) [Sperber, D. and Wilson, D., 1995. Relevance: communication and cognition. 2nd ed. Oxford: Blackwell.] Relevance Theory of comprehension. We show that the combination of the two theories can provide a more complete account of the mechanisms and processes underlying situation assessment, or sense-making, and is consistent with the situated approach to SA.     

Differential proteomics via probabilistic peptide identification scores

Relative quantitation is key to enable differential proteomics and hence answer biological questions by comparing samples. Classical approaches involve stable isotope labeling with/without spiked standards. Although stable isotopes may lead to precise results, their application is not straightforward. In Proteomics, 2004, 4, 2333-2351, we proposed an approach where we summed peptide identification scores to derive a semiquantitative abundance indicator. In this study, we combine such an indicator with a statistical test to detect differentially expressed proteins. We demonstrate the effectiveness of this method by using mixtures of purified proteins and human plasma spiked with proteins at low-nanomolar concentrations. The impact of the number of repeated experiments is discussed, and we show that the statistical test we use performs well with two to three repetitions, whereas a classical t-test would require at least four repetitions to achieve the same performance. Typically, 2.5-5-fold changes are detected with 90-95% confidence in human plasma. The method is finally characterized by deriving estimates of its false positive and negative rates. This new characterization is valid for a wider class of methods such as spectrum sampling (Liu, H.; Sadygov, R. G.; Yates, J. R. III. Anal. Chem. 2004, 76, 4193-4201).     

Speech perception, vocabulary, and the development of reading skills in english among Korean- and English-speaking children.

This study examined the roles of speech perception and phonological processing in reading and spelling acquisition for native and nonnative speakers of English in the 1st grade. The performance of 50 children (23 native English speakers and 27 native Korean speakers) was examined on tasks assessing reading and spelling, phonological processing, speech perception, and receptive vocabulary at the start and end of the school year. Korean-speaking children outperformed native English speakers on each of the literacy measures at the start and end of 1st grade, despite differences in their initial phonological representations and processing skills. Furthermore, speech perception and phonological processing were important contributors to early literacy skills, independent of oral language skills, for children from both language groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of rHuEpo on blood transfusions in preterm infants after the fifteenth day of life

Ex vivo T cell depletion of allogeneic grafts is associated with a high (up to 80%) rate of mixed chimerism (MC) posttransplantation. The number of transplanted progenitor cells is an important factor in achieving complete donor chimerism in the T cell depletion setting. Use of granulocyte colony-stimulating factor (G-CSF) peripheral blood allografts allows the administration of large numbers of CD34+ cells. We studied the chimeric status of 13 patients who received allogeneic CD34+-selected peripheral blood progenitor cell transplants (allo-PBPCTs/CD34+) from HLA-identical sibling donors. Patients were conditioned with cyclophosphamide (120 mg/kg) and total-body irradiation (13 Gy in four fractions). Apheresis products were T cell-depleted by the immunoadsorption avidin-biotin method. The median number of CD34+ and CD3+ cells infused was 2.8x10(6)/kg (range 1.9-8.6x10(6)/kg) and 0.4x10(6)/kg (range 0.3-1x10(6)/kg), respectively. Molecular analysis of the engraftment was performed using polymerase chain reaction (PCR) amplification of highly polymorphic short tandem repeat (PCR-STR) sequences in peripheral blood samples. MC was detected in two (15%) of 13 patients. These two patients relapsed at 8 and 10 months after transplant, respectively. The remaining 11 patients showed complete donor chimerism and were in clinical remission after a maximum follow-up period of 24 months (range 6-24 months). These results were compared with those obtained in 10 patients who were treated with T cell-depleted bone marrow transplantation by means of elutriation and who received the same conditioning treatment and similar amounts of CD3+ cells (median 0.45x10(6)/kg; not significant) but a lower number of CD34+ cells (median 0.8x10(6)/kg; p = 0.001). MC was documented in six of 10 patients (60%), which was significantly higher than in the allo-PBPCT/CD34+ group (p = 0.04). We conclude that a high frequency of complete donor chimerism is achieved in patients receiving allo-PBPCT/CD34+ and that this is most likely due to the high number of progenitor cells administered.     

Phonological awareness and reading acquisition in English- and Punjabi-speaking Canadian children.

This study examined whether the same component processes are involved in reading acquisition for native and nonnative speakers of English in the 1st grade. The performance of 88 children was examined on tasks assessing reading skill, phonological processing, and syntactic awareness. Fifty children were native English speakers (L1), and 38 children were from Punjabi-speaking families (ESL). Although measures of word recognition and phonological processing successfully discriminated between average and poor readers, they did not discriminate between the 2 language groups. Analyses of word reading errors revealed similar error patterns for ESL and L1 children, yet different error patterns for average and poor readers. For both L1 and ESL children, reading difficulties appear to be strongly linked with impaired phonological processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)