Upper and lower limits for the microbending loss in arbitrary single-mode fibers

Upper and lower limits for the actual microbending loss of single-mode fibers with arbitrary refractive index profile are given. These limits strongly depend on the shape of the actual fundamental mode field. It is shown that the minimum splice loss due to a small offset for a given microbending loss is obtained for a fiber with a Gaussian fundamental mode field. Fibers with similar splice loss and non-Gaussian fundamental mode fields like multiple-clad single-mode fibers will exhibit significantly larger microbending losses.     

Impact of comorbid oppositional or conduct problems on attention-deficit hyperactivity disorder

OBJECTIVE: To investigate whether the presence of comorbid oppositional defiant disorder (ODD) or conduct disorder (CD) alters the correlates of attention-deficit hyperactivity disorder (ADHD). METHOD: Three groups of children (33 "pure" ADHD, 46 ADHD + ODD, and 12 ADHD + CD) were compared on measures of ADHD, aggression, anxiety, parental psychopathology, self-esteem, school, and social-emotional functioning. RESULTS: Findings indicated that the presence of comorbid oppositional or conduct problems in children with ADHD altered the correlates of ADHD across a number of areas, including greater ADHD symptom severity and social dysfunction. Nevertheless, some correlates were more closely linked with the comorbid condition of ADHD + CD (e.g., higher aggression, anxiety, and maternal pathology, as well as decreased self-esteem), while others appeared more closely linked with ADHD + ODD (e.g., social withdrawal, elevated academic achievement paired with higher perceived scholastic competence). CONCLUSIONS: Findings support the distinctive profiles of the disruptive behavior disorder groups and emphasize the deleterious effects on the quality of life experienced by the comorbid conditions. The need for syndrome-specific interventions is stressed.     

Modeling of process forces with consideration of tool wear for machining of sintered steel alloy for application to valve seat in a combustion engine

The reliable and precise machining of cylinder head components in the combustion engine represents a crucial and complicated step in the production process. In industrial manufacturing processes, disturbances are inevitable and provide a measure of uncertainty in each production step. Increasingly, the influence of such uncertainties is being evaluated using simulation models. To determine the performance quality of the model, a suitable cutting material and the edge geometry must be identified. In this paper, experimental investigation of polycrystalline cubic boron nitride grades for machining valve seats made of powder metallurgy steel in a combustion engine is presented. Then, a mechanistic approach is used to establish a prediction model of the process forces based on the experimentally determined data set.     

Modal analysis of waveguide antennas with arbitrary cross sections

An approach is given to analyze the modal coupling of open-ended waveguides with arbitrary cross sections located in a conducting screen. The presented theory enables the determination of reflection characteristics of a single waveguide, as well as the analysis of mutual coupling between elements in waveguide antenna arrays. The field inside each waveguide is expressed as a sum of the transverse-electric and transverse-magnetic modes and expressions for the mutual admittances of modes excited at the aperture are obtained using a direct integration method. From these expressions, the mode reflection and conversion coefficients are determined. Computed and measured results are presented. Furthermore, this approach has been used to design a new type of horn antenna with high return loss and equal radiation patterns in the two principle planes     

Model-driven development: a metamodeling foundation

Metamodeling is an essential foundation for MDD, but there's little consensus on the precise form it should take and role it should play. The authors analyze the underlying motivation for MDD and then derive a concrete set of requirements that a supporting infrastructure should satisfy. They discuss why the traditional "language definition" interpretation of metamodeling isn't a sufficient foundation and explain how it can be extended to unlock MDD's full potential.     

Uncoupling of nonreceptor tyrosine kinases from PLC-gamma1 in an SLP-76-deficient T cell

Activation of nonreceptor protein tyrosine kinases (PTKs) is essential for T cell receptor (TCR) responsiveness; however, the function of individual PTK substrates is often uncertain. A mutant T cell line was isolated that lacked expression of SLP-76 (SH2 domain-containing leukocyte protein of 76 kilodaltons), a hematopoietically expressed adaptor protein and PTK substrate. SLP-76 was not required for TCR-induced tyrosine phosphorylation of most proteins, but was required for optimal tyrosine phosphorylation and activation of phospholipase C-gamma1 (PLC-gamma1), as well as Ras pathway activation. TCR-inducible gene expression was dependent on SLP-76. Thus, coupling of TCR-regulated PTKs to downstream signaling pathways requires SLP-76.     

Pharmacological investigations with the combination sulfamoxole/trimethoprim, a new broadspectrum chemotherapeutic agent (author's transl)

Investigations were conducted with the combination of N1-(4,5-dimethyl-2-oxazolyl)-sulfanilamide (sulfamoxole) and 2,4-diamino-5-(3,4,5-trimethoxy-benzyl)-pyrimidine (trimethoprim) (CN 3123, Nevin, Supristol) in a dose ratio of 5:1, with respect to pharmacological activity and possible side effects. The effects obtained with the combination CN 3123 were compared with those of the single substances. In a dose range comparable to that as used in clinical treatment, there were no effects on cardiovascular or respiratory functions, on functions of autonomic and central nervous system, on contractility of smooth muscles and on data of clinical chemistry such as urine and electrolyte excretion, blood sugar, blood coagulation and liver function tests. Doses which are 5 to 10 times higher than the initial dose or 10 to 20 times higher than the maintenance dose used in man caused an increase of urine and sodium excretion without influencing potassium and chloride output. There were no signs of sedation as alteration of motility or EEG patterns, but in mice and rats there was an increase in both duration and depth of anaesthesia caused by barbiturates or ether. Only in a dose range 30 to 40 times higher than the initial dose for man there were some slight alterations with respect to cardiovascular system and liver function tests. In vitro, with high concentrations of CN 3123 there was a weak, unspecific spasmolytic effect on the isolated ureter and an increase in the refractory period of the guinea pig atrium. There were no hints that the side effects seen with separate administration of high or very high doses of sulfamoxole or trimethoprim were increased or poteniated by their simultaneous administration. Slight side effects in animals were only observed with doses exceeding the tenfold of the doses for therapeutic use in men. Therefore, the therapeutic range of CN 3123 seems to be more than adequate.     

A demonstrator for a low-cost, cordless, multi-carrier spread-spectrum system

Because of the need for spectrally efficient systems for wireless communication, many research activities have been carried out in the area of spread-spectrum techniques. Multi-carrier spread-spectrum (MC-SS) is a new modulation technique with better spectral properties than direct-sequence spread-spectrum (DS-SS). In this paper, a new MC-SS system is introduced. A customized surface acoustic wave (SAW) filter has been designed as a fast analog correlator. A demonstrator testbed has been developed for the 2.4-GHz industrial, scientific, and medical (ISM) band. Experimental measurements of the intermediate frequency (IF) and baseband correlation are presented.