Electrical conduction in CuWO4 crystals

The d.c. electrical conductivity and thermoelectric power of CuWO₄ have been measured in the temperature range 300 to 700 K on unannealed and annealed single crystals and on polycrystalline pellets. It has been found that CuWO₄ is an n-type semiconductor. Relevant conduction mechanisms appropriate to the regions below and above 455 K are discussed on the basis of the experimental data on activation energy, mobility and carrier concentration.     

Stimulation in vitro of galactocerebroside galactosidase by N-decanoyl 2-amino-2-methylpropanol

Amides resembling ceramide (fatty acyl sphingosine) were synthesized and tested in vitro for their effects on the rat brain β-galactosidase which hydrolyzes galactosyl ceramide. The N-decanoyl derivative of 2-amino-2-methyl-1-propanol was most effective, giving a 34% stimulation at 0.15 mM concentration and a 60% stimulation at maximal levels. Addition of a hydroxyl group in the 3 position reduced the degree of stimulation, as did increasing or decreasing the length of the fatty acid portion. Omission of the branched methyl group resulted in inhibition instead of stimulation. Kinetic analysis indicates that the stimulator does not affect the binding of substrate to enzyme, but does speed the rate of hydrolytic action. Stimulation was also observed with the cerebrosidase in spleen and kidney. It is suggested that the stimulators act on an enzyme site other than the substrate-active site.     

Survey of multi-objective optimization methods for engineering

A survey of current continuous nonlinear multi-objective optimization (MOO) concepts and methods is presented. It consolidates and relates seemingly different terminology and methods. The methods are divided into three major categories: methods with a priori articulation of preferences, methods with a posteriori articulation of preferences, and methods with no articulation of preferences. Genetic algorithms are surveyed as well. Commentary is provided on three fronts, concerning the advantages and pitfalls of individual methods, the different classes of methods, and the field of MOO as a whole. The Characteristics of the most significant methods are summarized. Conclusions are drawn that reflect often-neglected ideas and applicability to engineering problems. It is found that no single approach is superior. Rather, the selection of a specific method depends on the type of information that is provided in the problem, the users preferences, the solution requirements, and the availability of software.     

Ceramide induces hepatocyte cell death through disruption of mitochondrial function in the rat

Although ceramide signaling pathways have been implicated in cell death, neither their role in hepatocellular death nor the cellular mechanisms mediating ceramide-induced cell death are known. The mitochondrial membrane permeability transition (MMPT) has been proposed as a common final pathway in cell death. Thus the aims of our study were to determine if ceramides cause hepatocellular death by necrosis and not apoptosis as confirmed by morphology and the absence of internucleosomal DNA cleavage. Ceramide-mediated hepatocyte necrosis was acyl chain-length, concentration, and time-dependent. Ceramides induced cell necrosis was associated with adenosine triphosphate (ATP) depletion and mitochondrial depolarization suggesting that ceramides caused mitochondrial dysfunction. In isolated mitochondria, ceramides induced the cyclosporine A-sensitive MMPT in an acyl chain-length and concentration dependent manner. Ceramide toxicity was specific as the less potent dihydro form did not induce cell necrosis, significant ATP depletion, mitochondrial depolarization nor the MMPT. In conclusion, ceramide induced cell death is acyl-chain length dependent and mediated by the MMPT. These data show for the first time that ceramide acts as a mediator of hepatocyte necrosis by causing mitochondrial failure.     

Atypical squamous cells of undetermined significance in the pediatric population. Implications for management and comparison with the adult population

OBJECTIVE: To determine the significance of an atypical squamous cells of undetermined significance (ASCUS) diagnosis in patients 18 years or younger. STUDY DESIGN: From June 1994 to June 1995, 630 cervicovaginal smears were performed on patients 18 years or younger (mean age 16.4, range 14-18) at University Hospitals of Cleveland. Of these patients, 69 (10.9%) were diagnosed with ASCUS or ASCUS with a qualifying statement. Follow-up cervicovaginal smears, biopsies and charts were reviewed for a 12-18-month period following the initial diagnosis of ASCUS. RESULTS: The study population was sexually active: 63% were gravid, 21% were multigravid, 68% had a history of sexually transmitted diseases (STDs), and 32% had multiple STDs. Follow-up cervicovaginal smears or biopsies were obtained on 46 patients (32 cervicovaginal smears and 14 biopsies/endocervical curettage cases). Mild to moderate dysplasia was identified in 21.6% of patients (10.8% on cervicovaginal smears and 10.8% on biopsies), and a repeat diagnosis of ASCUS was given in 37%. In patients with a repeat diagnosis of ASCUS, a follow-up cervicovaginal smear or biopsy revealed dysplasia in an additional 13%. The overall rate of dysplasia was 34.7%. CONCLUSION: Regardless of age, the diagnosis of ASCUS in a sexually active patient population has significant implications. Furthermore, we recommend that these patients be managed the same way as high-risk adult patients.     

Computer-aided measurement of Q-factor with application toquasi-optical open resonators

A technique for automated measurement of Q based on the observation of resonator response at a set of points near resonance is presented. The resonance curve, suitably corrected for noise and the presence of unwanted modes, is transformed into a linear graph. On the basis of this transformation, an analysis of error in the measurement of Q is carried out. An example of measurement on an open resonator at 97 GHz, with an accuracy of about 1% in the evaluation of Q is included     

An efficient implementation of adjoint sensitivity analysis for optimal control problems

In this paper an efficient implementation of design sensitivity analysis techniques is presented for nonlinear optimal control problems using the adjoint variable method. Techniques for functionals (integrals) and dynamic response (or pointwise) constraints are developed. Emphasis is placed on the proper choice of numerical techniques which exploit the structure of the problem to achieve efficiency. Numerical results for two optimal control examples show great improvement over previous implementations. Unlike previous results the computational effort required for DSA is shown to increase only linearly with the number of discretization points used and is a much smaller percentage of total CPU time.