Children, robotics, and education

Popular interest in robotics has increased astonishingly in the last few years. Robotics is seen by many as offering major new benefits in education at all levels. Before rushing to exploit this popularity, educators should ask serious questions about the universality and longevity of the robotics phenomenon. Is it a fashion? To be useful, the energy released by robotics must be sustained and universal, and the means of exploiting it must be systematic. Universities define their own robotics curriculum, but most schools lack both the resources and the freedom to do this, and must work with a national curriculum. If it can be shown that robotics has sustained potential in education, it seems inevitable that new ways need to be found to integrate it into the school curriculum.     

Tilted superlattice composition profile determined by photoluminescence and thermal disordering

The composition profile of an (AlAs)_1/2(GaAs)_1/2 tilted superlattice is characterized for the first time. The tilted superlattice sample is thermally disordered, and the energy of the direct band gap photoluminescence peak is measured as a function of increasing layer interdiffusion. The shift in the photoluminescence peak energy after completely disordering the tilted superlattice is 39 meV. A theoretical model is used to simulate the change in band gap as a function of layer interdiffusion for several composition profiles. The profile that gives the best fit to the experimental data is chosen. The tilted superlattice composition profile is found to be sinusoidal, varying from Al_0.40Ga_0.60As to Al_0.60Ga_0.40As.     

Advanced thin-film silicon-on-sapphire technology: microwavecircuit applications

This paper reviews the prospects of thin-film silicon-on-sapphire (TFSOS) CMOS technology in microwave applications in the 1-5 GHz regime and beyond and presents the first demonstration of microwave integrated circuits based on this technology, MOSFET's optimized for microwave use, with 0.5-μm optically defined gate lengths and a T-gate structure, have f_t values of 25 GHz (14 GHz) and f_max values of 66 GHz (41 GHz) for n-channel (p-channel) devices and have noise figure values below 1 db at 2 GHz, some of the best reported performance characteristics of any silicon-based MOSFET's to date. On-chip spiral inductors exhibit quality factors above ten. Circuit performance compares favorably with that of other CMOS-based technologies and approach performance levels similar to those obtained by silicon bipolar technologies. The results demonstrate the significant potential of this technology for microwave applications     

Ahch, the mouse homologue of DAX1: cloning, characterization and synteny with GyK, the glycerol kinase locus

We cloned the murine full-length cDNA encoding Ahch, the mouse homologue of DAX1 (DSS-AHC Region on Human X Chromosome, Gene1) which is the gene responsible for human X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH). Sequence analysis revealed that the murine and human cDNAs have 65% aa identity and 75% aa similarity overall. The cysteine residues in the putative DNA binding domain, which may interact with Zn2+ ions to form zinc fingers, are 100% conserved between the two species, indicating that the novel zinc-finger structures in DAX1 may be functional. In addition, mouse interspecific backcrosses show that the Ahch gene is closely linked to the glycerol kinase locus, GyK, on the mouse X chromosome, indicating that the order of the loci is conserved in this syntenic region between mouse and human.     

Pigmentation phenotypes of variant extension locus alleles result from point mutations that alter MSH receptor function

Coat colors in the chestnut horse, the yellow Labrador retriever, the red fox, and one type of yellow mouse are due to recessive alleles at the extension locus. Similarly, dominant alleles at this locus are often responsible for dark coat colors in mammals, such as the melanic form of the leopard, Panthera pardus. We show here that the murine extension locus encodes the melanocyte-stimulating hormone (MSH) receptor. In mice, the recessive yellow allele (e) results from a frameshift that produces a prematurely terminated, nonfunctioning receptor. The sombre (Eso and Eso-3J) and tobacco darkening (Etob) alleles, which both have dominant melanizing effects, results from point mutations that produce hyperactive MSH receptors. The Eso-3J receptor is constitutively activated, while the Etob receptor remains hormone responsive and produces a greater activation of its effector, adenylyl cyclase, than does the wild-type allele.     

Pectoralis major tendon avulsion in association with a proximal humerus fracture

We report a very rare case of an avulsion of the pectoralis major tendon in association with a two-part proximal humerus fracture. Pectoralis major tendon avulsion was confirmed intraoperatively during open reduction and internal fixation of the humerus fracture. In retrospect, the preoperative radiographic finding of posterolateral and proximal displacement of the humeral shaft suggested an injury to the pectoralis major. Because others have reported that the best treatment of a pectoralis major tendon avulsion is surgical repair, we feel that it is important to suspect such an injury in a proximal humerus fracture when this anatomic displacement is present.     

Social support knowledge and behavior and relational intimacy: A dyadic study.

Examined the relationships among social support knowledge, supportive behavior, intimacy with one's spouse, and satisfaction with support provided by one's spouse among 41 Israeli kibbutz couples. The hypothesis that support knowledge and support behavior influence the intimacy between couples and increase satisfaction with spouse's social support efforts was tested. Alternative causal mechanisms are explored with simultaneous equation modeling. Results indicate that satisfaction with social support behavior by one's spouse is mediated entirely by intimacy with one's spouse. Results also indicate that partner's knowledge about social support behavior directly affects intimacy and indirectly generates social support satisfaction independent of actual supportive behavior. The findings do not differ by sex. The consistency of the findings with family behavior exchange theory and implications for marital therapy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Function and sensitivity of signal processing systems based on addition followed by limiting

We show for the first time that signal processing schemes based on noncoherent signal addition will require signal transfer characteristics exhibiting high degrees of curvature. We quantify this by proposing a set of single-input, dual-output, power-conserving transfer functions and generating designs based on these characteristics. We then analyze the sensitivity of such a design scheme to nonidealities in the signal level and device behavior, and show that a sampling operation is only possible for transfer characteristics with residual "low" output of less than about 10% and low intensity reflectivity higher than 98%. For single device signal loss of up to 0.1 dB, we show that the best possible crosstalk-to-noise ratio in a packet forwarder (27 dB), is limited by the availability of the sampling operation.