Partitioning the UMLS semantic network

The unified medical language system (UMLS) integrates many well-established biomedical terminologies. The UMLS semantic network (SN) can help orient users to the vast knowledge content of the UMLS metathesaurus (META) via its abstract conceptual view. However, the SN itself is large and complex and may still be difficult to comprehend. Our technique partitions the SN into smaller meaningful units amenable to display on limited-sized computer screens. The basis for the partitioning is the distribution of the relationships within the SN. Three rules are applied to transform the original partition into a second more cohesive partition     

Impact Ionization in GaAs within A Screened Exchange Density Functional Formalism

We present the results of a fully first-principles calculation of impact ionization rates in GaAs within the density functional theory formalism, using a screened-exchange approach and the highly accurate all-electron full-potential linearized augmented plane wave (FLAPW) method. The calculated impact ionization rates show a marked orientation dependence in k space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab-initio calculations of pair production rates in new and more complex materials.     

Evidence that deficient IFN-gamma production is a biological basis of herpes simplex virus type-2 neurovirulence

Although immune response control of herpes simplex virus (HSV) has been well demonstrated, numerous HSV-2 strains are neurovirulent in immunocompetent mice. Using an RNase protection assay and an ELISA, we found that HSV-2-infected mice exhibited a deficient IFN-gamma response, an inability to clear virus, and eventual death. An HSV-based amplicon vector expressing mouse IFN-gamma was constructed and packaged into HSV-1-helper virus (HSV(pIFN-gamma)). In mice treated with HSV(pIFN-gamma), (i) the LD50 of HSV-2(G) increased 5000-fold, (ii) intracerebral IFN-gamma expression increased 10-fold, and (iii) HSV titer rapidly decreased. We suggest that the deficient IFN-gamma response is a basis for HSV-2 neurovirulence in mice.     

Interaction of cholecystokinin and somatostatin with a selective mu-opioid agonist and mu- and kappa-antagonists in thermoregulation

We examined the effects of intracerebroventricular (i.c.v.) injections of cholecystokinin-octapeptide (CCK-8) and somatostatin (SST) and the interactions of these neuropeptides with the selective opioid antagonists, CTAP (mu) and nor-BNI (kappa) and the mu-agonist, PL017, on body temperature (Tb) of the rat at normal ambient temperature (21 +/- 0.5 degrees C). CCK-8 produced short-lasting (15-60 min), dose-related increases in Tb in a dose range of 20 to 900 ng but did not change the Tb at lower doses (0.1-2 ng). Lower doses of SST (1 and 2 micrograms) produced hyperthermia (30-60 min) and a higher dose of SST (10 micrograms) caused hypothermia (30-45 min). PL017 (1 microgram, i.c.v.), alone and in combination with CCK-8, produced hyperthermia. The CCK-8 (300 ng)-induced hyperthermia was blocked by pretreatment of rats with CTAP (1 microgram, i.c.v.), suggesting that the higher doses of CCK-8 increase Tb through the interaction with mu-receptors or the enhancement of release of endogenous opioids acting on the mu-receptor. The hyperthermia elicited by a lower dose of SST (1 microgram) was prevented by pretreatment with CTAP but not with nor-BNI (1 microgram, i.c.v.). Pretreatment with nor-BNI blocked the higher dose (10 micrograms) of SST-induced hypothermia. PL017 or CTAP did not prevent the hypothermic effect of that dose of SST. These results indicate that a lower dose of SST (1 microgram) stimulates the mu-receptor (directly or indirectly) and a higher dose (10 micrograms) interacts with the kappa-receptor in regulation of Tb. Thus, the effects of both CCK-8 and SST on Tb appear to involve the endogenous opioid system.     

Effect of thiourea dioxide on the dynamics of continuous homophase synthesis of fibre-forming copolymers of acrylonitrile,methyl acrylate,and 2-acrylamido-2-methylpropanesulfonic acid

The effect of thiourea dioxide on the dynamics of homophase synthesis of copolymers of acrylonitrile, methyl acrylate, and 2-acrylamido-2-methylpropanesulfonic acid in 51.5% aqueous solution of NaSCN was investigated and its role in decreasing the induction period of the process was demonstrated. The effect of the synergism of 2-acrylamido-2-methylpropanesulfonic acid and thiourea dioxide, which reduces the induction period of synthesis, was established.Translated from Khimicheskie Volokna, No. 6, pp. 31–35, November–December, 1994.     

Numerical investigation of the temperatures and thermal stresses in thermal treatment of metallic articles

An algorithm is proposed for the numerical computation of the temperatures, stresses, and strains in articles during heat treatment. Specific computations are performed for plates from ShKh15 steel.