Optimal test-times for intermittent faults

Su et al. (1978) considered continuous and repetitive tests for a continuous-parameter Markov model with intermittent faults. Periodic tests for intermittent faults are scheduled at times k·T (k=1, 2,...). This paper presents a simple algorithm to compute the optimal time to minimize the mean cost until detection when the test model is imperfect. First an upper bound is found for the optimal time. Then a bisection-algorithm is used to minimize the cost of detecting faults for a system in which faults are intermittent and unpredictable. Using this algorithm, the solution of example 1 is better than that of Nakagawa and Yasui (1989) by at least 10%. This algorithm can be more useful than the Newton-Raphson method to locate an optimum because Newton-Raphson involves the first derivative whereas the bisection method does not     

Peripheral airways obstruction on high-resolution computed tomography in chronic severe asthma

BACKGROUND: An association between fats and colorectal carcinoma has been suggested, but the epidemiologic evidence by type of dietary fat is far less clear. Colorectal carcinoma rates have been relatively low in Mediterranean countries compared with most other Western countries, but the components of the Mediterranean diet responsible for this favorable pattern are unclear. METHODS: The relationship between various added (seasoning) fats and colorectal carcinoma risk was investigated using data from a case-control study conducted between January 1992 and June 1996 in six Italian areas. Cases were 1953 patients with incident, histologically confirmed colorectal carcinoma (1225 of the colon and 728 of the rectum) admitted to the major teaching and general hospitals in the study areas. Controls were 4154 subjects with no history of cancer who were admitted to hospitals in the same catchment areas for acute, nonneoplastic diseases unrelated to the the digestive tract and requiring no long term modifications of diet. Dietary habits were investigated using a validated food frequency questionnaire including 78 items. Lipid intake was estimated by taking into account the content of seasoning lipids in different dishes, the frequency of consumption and portion size of each dish, and individual fat intake patterns. RESULTS: The odds ratios (OR) for successive tertiles of olive oil intake, compared with the lowest one, were 0.87 (95% confidence interval [CI], 0.75-1.01) and 0.83 (95% CI, 0.70-0.99) (chi2trend = 4.49, P = 0.03) when colorectal carcinoma was analyzed as a whole, 0.82 (95% CI, 0.68-0.98) and 0.81 (95% CI, 0.66-0.99) (chi2trend = 4.05, P = 0.04) for colon carcinoma, and 0.96 (95% CI, 0.77-1.19) and 0.88 (95% CI, 0.66-1.12) for rectal carcinoma. For specific seed oils (including sunflower, maize, peanut, and soya), the OR for colorectal carcinoma was 0.91 in the highest tertile of intake, and the corresponding values were 1.01 for mixed seed oils and 0.93 for butter. None of these estimates was significantly different from the unity. Allowance for vegetable intake attenuated the apparent protection from olive oil consumption (OR, 0.94 for colon and 0.97 for rectum for the highest tertile), which still was apparent in younger subjects (OR, 0.82 for colon and 0.69 for rectum). CONCLUSIONS: In this study, seasoning fats did not appear to increase the risk of colorectal carcinoma, and there was little evidence for a differential effect by fat type. If such a differential effect exists, it is minor and could favor olive oil.     

Survival of Taenia solium cysticerci in carcasses of pigs kept at 4 C

In the present study, the survival of cysticerci of Taenia solium in carcasses of 1 Small-Ear-Miniature and 2 Landrace Small-Ear-Miniature pigs kept in a refrigerator at 4 C was determined. The viability of the cysticerci was determined by observing evagination and active movement of the scolex under a fluorescent light after digestion in pig bile. Although no viable cysticerci were found after day 30, 58.8% cysticerci survived between day 26 and day 30. Moreover, more than 80% of the cysticerci were viable between day 1 and day 25. These findings indicate that taeniasis solium can be transmitted through eating raw or undercooked pork or viscera of pigs following refrigeration at 4 C for less than 30 days.     

Ferroic Phase Transitions in (Na1/2Bi1/2)TiO3 Crystals

The ferroic phase-transition behavior of two (Na_1/2Bi_1/2)TiO₃(NBT) crystals grown by flux and by the Czochralski method has been investigated in the present study. Although both the tetragonal and the rhombohedral phases of NBT are expected to be ferroelastic, these crystals exhibit different ferroelastic behavior. The two NBT crystals also show differences in the amount of temperature hysteresis and the thermal expansion coefficients. These differences can be attributed to nonstoichiometry and structural variations dependent on the growing method. The present investigation has revealed a second maximum at −450°C in dielectric constant (( T )) curves, which could indicate that the intermediate tetragonal phase is either polar or antipolar. This maximum, however, originates from space-charge polarization and interaction between the charge carrier and the electrode, such that the tetragonal phase, in fact, is para-electric. The diffuse phase transition (DPT) of the NBT crystal, therefore, is from a paraelectric and ferroelastic tetragonal phase to a ferroelectric and ferroelastic rhombohedral phase. The crystallographic supergroup-subgroup relationships in the ferroic phase transitions of NBT crystals are discussed.     

Activation of the genetically defined m1 muscarinic receptor potentiates N-methyl-D-aspartate (NMDA) receptor currents in hippocampal pyramidal cells

Evidence suggests that cholinergic input to the hippocampus plays an important role in learning and memory and that degeneration of cholinergic terminals in the hippocampus may contribute to the memory loss associated with Alzheimer's disease. One of the more prominent effects of cholinergic agonists on hippocampal physiology is the potentiation of N-methyl-D-aspartate (NMDA)-receptor currents by muscarinic agonists. Here, we employ traditional pharmacological reagents as well as m1-toxin, an m1 antagonist with unprecedented selectivity, to demonstrate that this potentiation of NMDA-receptor currents in hippocampal CA1 pyramidal cells is mediated by the genetically defined m1 muscarinic receptor. Furthermore, we demonstrate the colocalization of the m1 muscarinic receptor and the NR1a NMDA receptor subunit at the electron microscopic level, indicating a spatial relationship that would allow for physiological interactions between these two receptors. This work demonstrates that the m1-muscarinic receptor gene product modulates excitatory synaptic transmission, and it has important implications in the study of learning and memory as well as the design of drugs to treat neurodegenerative diseases such as Alzheimer's.     

Plasma from women with preeclampsia increases endothelial cell nitric oxide production

In preeclampsia, a factor in the maternal circulation alters endothelial function via a reduction in nitric oxide synthesis. We measured the in vitro effects of 2% plasma from women with preeclampsia, compared with 2% plasma from normotensive pregnant women, on cultured endothelial cell nitrite production and nitric oxide synthase activity. On finding differential effects, we measured the effects on cellular viability (assessed by lactate dehydrogenase levels) and performed a time course study. Endothelial cell nitrite production was found to be higher after exposure to plasma from the preeclamptic group than the normotensive pregnant group. The effects of long-term exposure (120 hours) were similar to those of short-term exposure (24 hours). In addition, nitric oxide synthase activity was significantly greater after exposure to preeclamptic plasma than after exposure to normotensive pregnant plasma. No differential effect on cellular viability was found. Contrary to our hypothesis, exposure of endothelial cells to preeclamptic plasma resulted in increased nitric oxide production and nitric oxide synthase activity.     

Microwave properties of traveling-wave electrodes in LiNbO3 electrooptic modulators

The microwave characteristics of a traveling-wave electrode in electrooptic modulators on z-cut LiNbO₃ crystals with buffer layers with various dielectric constants are calculated by a quasi-TEM analysis. The theoretical results are compared with the measured results on z-cut crystals for coplanar waveguide (CPW) electrodes. The agreement between the calculated and the measured results is good     

Adoptive immunotherapy for leukemia: donor lymphocytes transduced with the herpes simplex thymidine kinase gene for remission induction. HGTRI 0103

This study will evaluate the safety and efficacy of allogenic donor lymphocyte infusions in patients who have relapsed hematologic malignancies after allogeneic bone marrow transplantation (BMT). Donor lymphocyte transfusions have resulted in the cure of some patients with relapsed leukemia or lymphoproliferative disorder after allogeneic BMT, but has been complicated by the development of graft versus host disease (GvHD). We hypothesize that a retroviral vector containing the Herpes simplex thymidine kinase (HStk) gene will allow for retention of the anti-leukemia response of transfused donor lymphocytes while allowing for the adverse effects of GVHD to be mitigated. Patients with relapsed hematologic malignancies after allogeneic BMT will be infused with ex vivo gene modified donor lymphocytes. The Herpes Simplex thymidine kinase (HStk) gene will be transduced into the cells ex vivo using LTKOSN. 1 vector supernate. Insertion of the HStk gene into lymphocytes confers a sensitivity to the anti-herpes drug ganciclovir (GCV). This selective destruction of donor lymphocytes in situ will be used to abrogate the effect of graft versus host disease, if it develops.