Secondary Electron Emission from Simple Metals: Comparative Studies for Al, Mg, and Be

In the secondary electron emission (SEE) from solids, the role of different excitation processes is now as ever of special interest from both the theoretical and the experimental points of view. Depending on the primary energy, the relative importance of different excitation mechanisms related to conduction as well as core electrons will be discussed for different simple metals. So far, first principles results are available only for Al for primary energies up to 10 keV. Starting from a microscopic description of the SEE based on the transport equation formalism, calculations were performed for other nearly-free-electron metals (Mg, Be) up to primary energies used in scanning electron microscopy. In this way, it is possible to obtain more general statements about the role of different excitation processes responsible for SEE. Special attention is devoted to the contribution of emitted electrons stemming from the excitation of conduction electrons by decay of bulk plasmons generated by the primary electron. The different strength of this excitation mechanism in Al, Mg, and Be is related to the different magnitude of the plasmon damping in these metals

Semiconductor grade, solar silicon purification project

The conversion of metallurgical grade silicon into semiconductor grade silicon by way of a three step SiF2 polymer transport purification process was investigated. Developments in the following areas were also examined: (1) spectroscopic analysis and characterization of (SiF2) sub x polymer and Si sub x F sub y homologue conversion; (2) demonstration runs on the near continuous apparatus; (3) economic analysis; and (4) elemental analysis

Semiconductor Grade, Solar Silicon Purification Project

A low cost by-product, SiF4, is reacted with mg silicon to form SiF2 gas which is polymerized. The (SiF2)x polymer is heated forming volatile SixFy homologues which disproportionate on a silicon particle bed forming silicon and SiF4. The silicon analysis procedure relied heavily on mass spectroscopic and emission spectroscopic analysis. These analyses demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). However, electrical analysis via crystal growth reveal that the product contains compensated phosphorus and boron

Semiconductor grade, solar silicon purification project

Experimental apparatus and procedures used in the development of a 3-step SiF2(x) polymer transport purification process are described. Both S.S.M.S. and E.S. analysis demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). Recent electrical analysis via crystal growth reveals that the product contains compensated phosphorus and boron. The low projected product cost and short energy payback time suggest that the economics of this process will result in a cost less than the goal of $10/Kg(1975 dollars). The process appears to be readily scalable to a major silicon purification facility

Polens e esporos associados a megafosseis vegetais em S.J. do Triunfo, PR, formação rio bonito (permiano)

The study of pollen and spores of a carbonatic siltstone at the base of the fossil-plant-bearing strata of the São João do Triunfo locality (Rio Bonito Formation, Tubarão Group, Paraná Basin in the south of the State of Paraná, Brazil) is here presented. It is part of a project that also includes similar studies of other localites, with the objective to improve biostratigraphic and paleoenvironmental interpretations. In fact, it contributes with additional information on the Permian paleofloral composition through the study of the relationships between "micro-" and "megaflora". In the present study, the main identified miospores belong to the following genera: Portalites. Vittatina, Protohaploxypinus, Striomonosaccites, Florinites, Apiculatisporites, Raistrickia, Leiotriletes, Calamospora and Punctatisporites. Monoporiti is predominant (45%). The percentage of trilete spores is 37%, but only 10% of them are ornamented. Monolete spores com prise 8% and both monosaccites and striatites make up 5% each. Regarding the age, this qualitative and quantitative composition would suggest a correspondence with the Early to Middle Artinskian, about the same as previously suggested by the plant megafossils alone. The low percentage of striatites is consistent with the low percentage of (and with the kind of glossopterids in the same horizons. Punctatisporites is probably related to some of the ferns, which are very abundant among the megafossils; Calamospora is probably related with the sphenopsids (Phylloteca and Annularia, occur together with Paracalamites). Lagenoisporites is a very common megaspore almost certainly related to Brasilodendron, the characteristic lycopsid of this phytozone

Megaspores from coals of the Triunfo Member, Rio Bonito Formation (Lower Permian), northeastern Parana State, Brazil

This paper presents the results of a detailed study of megaspores occurring in coal seams of the Triunfo Member, Rio Bonito Formation at Figueira, Parana State, Brazil. This coal-bearing sequence accumulated in a marine delta system during the Early Permian. Four species are described and illustrated: Lagenoisporites triunfensis, L. scutiformis, Sublagenicula cf. brasiliensis, and Setosisporites cf. furcatus. Of these, the two species of Lagenoisporites are predominant. Relationships to other megaspore species are discussed; and the temporal and spatial distributions of the four species in the Parana Basin are documented.74349150

Brain plasticity in neonatal brachial plexus palsies: quantification and comparison with adults' brachial plexus injuries

PurposeTo compare two populations of brachial plexus palsies, one neonatal (NBPP) and the other traumatic (NNBPP) who underwent different nerve transfers, using the plasticity grading scale (PGS) for detecting differences in brain plasticity between both groups.MethodsTo be included, all patients had to have undergone a nerve transfer as the unique procedure to recover one lost function. The primary outcome was the PGS score. We also assessed patient compliance to rehabilitation using the rehabilitation quality scale (RQS). Statistical analysis of all variables was performed. A p & LE; 0.050 set as criterion for statistical significance.ResultsA total of 153 NNBPP patients and 35 NBPP babies (with 38 nerve transfers) met the inclusion criteria. The mean age at surgery of the NBPP group was 9 months (SD 5.42, range 4 to 23 months). The mean age of NNBPP patients was 22 years (SD 12 years, range 3 to 69). They were operated around sixth months after the trauma. All transfers performed in NBPP patients had a maximum PGS score of 4. This was not the case for the NNBPP population that reached a PGS score of 4 in approximately 20% of the cases. This difference was statistically significant (p < 0.001). The RQS was not significantly different between groups.ConclusionWe found that babies with NBPP have a significantly greater capacity for plastic rewiring than adults with NNBPP. The brain in the very young patient can process the changes induced by the peripheral nerve transfer better than in adults.Scientific Assessment and Innovation in Neurosurgical Treatment Strategie

Missense mutations cluster within the carboxyl-terminal region of DAX-1 and impair transcriptional repression

DAX-1 is an orphan nuclear receptor that plays a key role in the development and function of the adrenal gland and hypothalamic-pituitary gonadal axis. Mutations in the gene encoding DAX-1 result in X-linked adrenal hypoplasia congenita (AHC). Affected boys typically present with primary adrenal failure in infancy or childhood and hypogonadotropic hypogonadism at the time of puberty. The majority of DAX1 mutations described to date are nonsense or frameshift mutations that result in premature truncation of the DAX-1 protein and loss of DAX-1 repressor function. Relatively few missense mutations in DAX1 have been reported. Here, we describe missense mutations in three additional families with X-linked AHC. When combined with previous reports, the DAX1 missense mutations appear to cluster within restricted regions of the putative ligand-binding domain of DAX-1 and affect amino acids that are evolutionarily conserved, suggesting that these regions correspond to critical functional domains. Transcription assays, using a variety of artificial and native target genes, were performed to assess the effects of these mutations on the function of DAX-1. All DAX-1 missense mutant constructs showed marked loss of repressor function, with the exception of I439S, a mutation previously shown to be associated with delayed-onset adrenal failure and incomplete hypogonadotropic hypogonadism. These data indicate that most DAX1 missense mutations associated with classic AHC exhibit marked loss of function. The locations of these mutations thereby identify important functional domains in the carboxyl-terminus of the protein

Attention Deficit Hyperactivity Disorder (ADHD) among longer-term prison inmates is a prevalent, persistent and disabling disorder

<p>Abstract</p> <p>Background</p> <p>ADHD is a common and disabling disorder, with an increased risk for coexisting disorders, substance abuse and delinquency. In the present study, we aimed at exploring ADHD and criminality. We estimated the prevalence of ADHD among longer-term prison inmates, described symptoms and cognitive functioning, and compared findings with ADHD among psychiatric outpatients and healthy controls.</p> <p>Methods</p> <p>At Norrtälje Prison, we approached 315 male inmates for screening of childhood ADHD by the Wender Utah Rating Scale (WURS-25) and for present ADHD by the Adult ADHD Self-Report Screener (ASRS-Screener). The response rate was 62%. Further, we assessed 34 inmates for ADHD and coexisting disorders. Finally, we compared findings with 20 adult males with ADHD, assessed at a psychiatric outpatient clinic and 18 healthy controls.</p> <p>Results</p> <p>The estimated prevalence of adult ADHD among longer-term inmates was 40%. Only 2 out of 30 prison inmates confirmed with ADHD had received a diagnosis of ADHD during childhood, despite most needed health services and educational support. All subjects reported lifetime substance use disorder (SUD) where amphetamine was the most common drug. Mood and anxiety disorders were present among half of subjects; autism spectrum disorder (ASD) among one fourth and psychopathy among one tenth. Personality disorders were common; almost all inmates presented conduct disorder (CD) before antisocial personality disorder (APD). Prison inmates reported more ADHD symptoms during both childhood and adulthood, compared with ADHD psychiatric outpatients. Further, analysis of executive functions after controlling for IQ showed both ADHD groups performed poorer than controls on working memory tests. Besides, on a continuous performance test, the ADHD prison group displayed poorer results compared with both other groups.</p> <p>Conclusions</p> <p>This study suggested ADHD to be present among 40% of adult male longer-term prison inmates. Further, ADHD and coexisting disorders, such as SUD, ASD, personality disorders, mood- and anxiety disorders, severely affected prison inmates with ADHD. Besides, inmates showed poorer executive functions also when controlling for estimated IQ compared with ADHD among psychiatric outpatients and controls. Our findings imply the need for considering these severities when designing treatment programmes for prison inmates with ADHD.</p