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Sensitivity Test (sensitivity + test)
Selected AbstractsA Global Sensitivity Test for Evaluating Statistical Hypotheses with Nonidentifiable ModelsBIOMETRICS, Issue 2 2010D. Todem Summary We consider the problem of evaluating a statistical hypothesis when some model characteristics are nonidentifiable from observed data. Such a scenario is common in meta-analysis for assessing publication bias and in longitudinal studies for evaluating a covariate effect when dropouts are likely to be nonignorable. One possible approach to this problem is to fix a minimal set of sensitivity parameters conditional upon which hypothesized parameters are identifiable. Here, we extend this idea and show how to evaluate the hypothesis of interest using an infimum statistic over the whole support of the sensitivity parameter. We characterize the limiting distribution of the statistic as a process in the sensitivity parameter, which involves a careful theoretical analysis of its behavior under model misspecification. In practice, we suggest a nonparametric bootstrap procedure to implement this infimum test as well as to construct confidence bands for simultaneous pointwise tests across all values of the sensitivity parameter, adjusting for multiple testing. The methodology's practical utility is illustrated in an analysis of a longitudinal psychiatric study. [source] The Prospects for Foreign Debt Sustainability in Post-Completion-Point Countries: Implications of the HIPC-MDRI FrameworkDEVELOPMENT POLICY REVIEW, Issue 2 2008Jacinta Nwachukwu The Enhanced HIPC Initiative was launched in 1999 to reduce the Net Present Value (NPV) of foreign debt of the world's poorest countries to a sustainable threshold of 150% of their exports. This article applies a simple growth-with-debt model to 16 post-completion-point HIPCs to assess whether this goal will be met by 2015. Its somewhat optimistic base-case projections suggest that participation in the current Enhanced HIPC-MDRI initiative will only reduce the NPV of their total external debt to 176% of exports by this date. Sensitivity tests which expose these countries to adverse exogenous shocks help draw attention to policies that could ensure that they do not again accumulate unsustainable debt levels. [source] A risk-averse user equilibrium model for route choice problem in signal-controlled networksJOURNAL OF ADVANCED TRANSPORTATION, Issue 4 2010William H.K. Lam Abstract This paper proposes a new risk-averse user equilibrium (RAUE) model to estimate the distribution of traffic flows over road networks with taking account the effects of accident risks due to the conflicting traffic flows (left- and right-turning and through traffic flows) at signalized intersections. It is assumed in the proposed model that drivers consider simultaneously both the travel time and accident risk in their route choices. The accident risk of a route is measured by the potential accident rate on that route. The RAUE conditions are formulated as an equivalent path-based variational inequality problem which can be solved by a path-based solution algorithm. It is shown that the traditional user equilibrium (UE) model is in fact a special case of the proposed model. A numerical example on a grid network is used to illustrate the application of the proposed model and to compare the results with the conventional UE traffic assignment. Numerical results show that the traditional UE model may underestimate the total system travel time and overestimate the system accident rate. Sensitivity tests are also carried out to assess the effects of drivers' preferences, signal control parameters (i.e., green time proportions), and various network demand levels on the route choice problem. Copyright © 2010 John Wiley & Sons, Ltd. [source] Naturally low carbonic anhydrase activity in C4 and C3 plants limits discrimination against C18OO during photosynthesisPLANT CELL & ENVIRONMENT, Issue 9 2000J. S. Gillon ABSTRACT The 18O content of CO2 is a powerful tracer of photosynthetic activity at the ecosystem and global scale. Due to oxygen exchange between CO2 and 18O-enriched leaf water and retrodiffusion of most of this CO2 back to the atmosphere, leaves effectively discriminate against 18O during photosynthesis. Discrimination against 18O (,18O) is expected to be lower in C4 plants because of low ci and hence low retrodiffusing CO2 flux. C4 plants also generally show lower levels of carbonic anhydrase (CA) activities than C3 plants. Low CA may limit the extent of 18O exchange and further reduce ,18O. We investigated CO2,H2O isotopic equilibrium in plants with naturally low CA activity, including two C4 (Zea mays, Sorghum bicolor) and one C3 (Phragmites australis) species. The results confirmed experimentally the occurrence of low ,18O in C4, as well as in some C3, plants. Variations in CA activity and in the extent of CO2,H2O isotopic equilibrium (,eq) estimated from on-line measurements of ,18O showed large range of 0,100% isotopic equilibrium (,eq= 0,1). This was consistent with direct estimates based on assays of CA activity and measurements of CO2 concentrations and residence times in the leaves. The results demonstrate the potential usefulness of ,18O as indicator of CA activity in vivo. Sensitivity tests indicated also that the impact of ,eq< 1 (incomplete isotopic equilibrium) on 18O of atmospheric CO2 can be similar for C3 and C4 plants and in both cases it increases with natural enrichment of 18O in leaf water. [source] Association of epidermal growth factor receptor mutations in lung cancer with chemosensitivity to gefitinib in isolated cancer cells from Japanese patientsEUROPEAN JOURNAL OF CANCER CARE, Issue 3 2007K. NAKATANI md, assistant professor Somatic mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene are reported to be associated with clinical responsiveness of lung cancer to gefitinib, an EGFR tyrosine kinase inhibitor. To elucidate the association between somatic mutations and the pharmacological actions of gefitinib, the chemosensitivity of isolated cancer cells from the lungs of Japanese patients to gefitinib was examined by the collagen gel-droplet embedded culture drug sensitivity test in vitro. In 30 specimens isolated from non-small-cell lung cancer patients, mutations were observed in eight tumour specimens (27%) and chemosensitivity to gefitinib was observed in seven specimens (23%). However, somatic mutations were not predominantly associated with chemosensitivity to gefitinib in vitro. Both mutation and chemosensitivity frequencies in this study were higher than those reported in studies from the United States, indicating a possible ethnic difference. Moreover, both frequencies were much higher in females than in males. Since a gender difference in chemosensitivity to gefitinib was observed in isolated cancer cells in vitro, this suggests that gefitinib works in part through the suppression of EGFR signalling, but that other factors, including sex-related factors, may participate in gefitinib action. [source] Functional MRI of the visual cortex and visual testing in patients with previous optic neuritisEUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2002A. R. Langkilde The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size of the activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated significantly to both the results of the contrast sensitivity test and to the Snellen visual acuity. Our results indicate that fMRI is a useful method for the study of ON, even in cases where the visual acuity is severely impaired. The reduction in activated volume could be explained as a reduced neuronal input; however, the greater asymmetry might point to a cortical reorganization as a consequence of neuronal damage. Future fMRI studies in ON will add to the understanding of the neural adaptive behaviour following ON. [source] Reconstruction of palaeo-burial history and pore fluid pressure in foothill areas: a sensitivity test in the Hammam Zriba (Tunisia) and Koh-i-Maran (Pakistan) ore depositsGEOFLUIDS (ELECTRONIC), Issue 2 2003L. Benchilla Abstract The burial and pore fluid pressure history of fluorite ore deposits is reconstructed: (i) at Hammam Zriba,Djebel Guebli along the eastern margin of the Tunisian Atlas; and (ii) at Koh-i-Maran within the northern part of the Kirthar Range in Pakistan. Both the deposits are hosted by Late Jurassic carbonate reservoirs, unconformably overlain by Late Cretaceous seals. Microthermometric analyses on aqueous and petroleum fluid inclusions with pressure,volume,temperature,composition (PVTX) modeling of hydrocarbon fluid isochores are integrated with kinematics and thermal 2D basin modeling in order to determine the age of mineralization. The results suggest a Cenozoic age for the fluorite mineralization and a dual fluid migration model for both ore deposits. The PVTX modeling indicates that the initial stage of fluorite cementation at Hammam Zriba occurred under fluid pressures of 115 ± 5 bars and at a temperature close to 130°C. At Koh-i-Maran, the F3 geodic fluorite mineralization developed under hydrostatic pressures of 200 ± 10 bars, and at temperatures of 125,130°C. The late increase in temperature recorded in the F3 fluorites can be accounted for by rapid rise of hotter fluids (up to 190°C) along open fractures, resulting from hydraulic fracturing of overpressured sedimentary layers. [source] A minipig model of high-fat/high-sucrose diet-induced diabetes and atherosclerosisINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2004Shoumin Xi Summary Type 2 diabetes is a major risk factor of the development of atherosclerosis in humans. However, studies examining mechanisms underlying diabetes-accelerated atherosclerosis have been limited by the lack of suitable humanoid animal models. Pigs have a cardiovascular system that is very similar to that of humans and is useful as a model for human physiology and pathophysiology. In this study, we established a new miniature pig model for studying dyslipidaemia and atherosclerosis in diabetes. Chinese Guizhou minipigs were fed a normal control diet or a high-fat/high-sucrose diet (HFSD) for 6 months. Plasma total cholesterol (TC), high-density lipoprotein cholesterol, triglyceride (TG), insulin and glucose were quantified at monthly intervals. The induction of insulin resistance and dysfunction of the pancreatic ,-cell were assessed by oral glucose tolerance test and insulin sensitivity test. The aortic fatty streak lesions were quantified following lipid staining with Sudan IV. During the feeding period, mild high plasma TC and TG were induced. At the end of 6 months, in HFSD-fed animals, the adipocytes were hypertrophic, fat deposit in the liver was observed, loss of pancreatic ,-cells was observed, and the aortic fatty streak lesions were clearly present in the animals' aortas. Our study established that miniature pigs that were fed a HFSD without adding dietary cholesterol developed insulin resistance, mild diabetes and atherosclerotic lesions. HFSD-fed miniature pigs may be good animal models for research on the treatment of diabetic dyslipidaemia complicated with atherosclerosis. [source] Discordant influence of amphotericin B on epirubicin cytotoxicity in primary hepatic malignant cells collected by a new primary culture techniqueJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 2 2006ZU-YAU LIN Abstract Background:, The purpose of this prospective study was to investigate whether amphotericin B (AmB) had any potential role in the systemic chemotherapy of primary hepatic malignancy using cancer cells collected by the authors' method of primary culture. Methods:, The specimens obtained by ultrasound-guided fine-needle aspiration biopsy (22 G) from 15 patients with hepatocellular carcinoma (HCC) and one with cholangiocarcinoma were plated into culture flask without disaggregation by trypsin-ethylenediamine tetra-acetic acid solution. Six patients with HCC and one patient with cholangiocarcinoma (7/16, 44%) had successful culture and the cancer cells at the 4th passage were continuously exposed to therapeutic ranges of epirubicin (0, 0.5, 1.0, 1.5, 2.0 µg/mL) with or without the combination of 2.5 µg/mL AmB for 24 h. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to evaluate the effects of the drugs. A human HCC cell line (HA 22T/VGH) was studied for comparison. Results:, Addition of AmB showed no influence on epirubicin cytotoxicity in two patients (one partial resistant HCC and one epirubicin-sensitive cholangiocarcinoma; 25%), augmentation of the epirubicin cytotoxicity in two patients (one total resistant HCC, partial resistant HA 22T/VGH cell line and one epirubicin-sensitive HCC; 37.5%), and decrease of epirubicin cytotoxicity in the remaining three (one partial resistant and two epirubicin-sensitive HCC; 37.5%). Conclusions:, Amphotericin B has a discordant influence on epirubicin cytotoxicity in primary cultured hepatic malignant cells. Application of AmB in the systemic chemotherapy of primary hepatic malignancy should be limited to patients with positive AmB effect evaluated by an in vitro sensitivity test such as the present method. [source] A case of suspected contact dermatitis in a juvenile cynomolgus monkey (Macaca fascicularis)JOURNAL OF MEDICAL PRIMATOLOGY, Issue 2008Joanne Morris Abstract Background, A 2-year-old male cynomolgus monkey (Macaca fascicularis) presented with vesicular dermatitis exhibiting freshly ruptured blisters, crusts, and papules on the extremities and face. Methods, Complete blood count, serum chemistry, skin biopsy, skin scrape, and culture of a fresh blister were initially submitted for diagnostics. Results, Skin biopsy of the affected area revealed a non-suppurative eosinophilic dermatitis with mild thickening of the epidermis. Serum chemistry showed a marked eosinophilia (1.74 × 103/,l, 17.4%). All other results were within normal limits. Initial differentials included contact dermatitis, immune-mediated disease such as pemphigus or psoriasis. Repeated blood work and skin biopsies were collected as well as serum for allergen-specific IgE latex and food allergy testing. Herpes B virus was added to the differential list after an oral lesion was noted upon repeated physical examination and samples were collected for testing. Repeat blood work maintained a marked eosinophilia and food allergy testing was within normal limits. Serum IgE for latex was equivocal and a follow-up latex sensitivity test was performed and was within normal limits. Repeated skin biopsies were consistent with acute eosinophilic spongiotic dermatitis with vesicles most likely due to contact dermatitis. No therapy was initiated during the diagnostic period and no etiology was confirmed. Conclusions, Over time the dermatitis and eosinophilia resolved spontaneously. The animal is currently free of any lesions and maintains an eosinophil count within normal limits. [source] A double-blind, randomized controlled trial of cystometry using saline versus 0.3 M potassium chloride infusion in women with overactive bladder syndrome,,NEUROUROLOGY AND URODYNAMICS, Issue 1 2007Joe Philip Abstract Aim To evaluate the effect of 0.3 M potassium chloride on cystometric parameters by comparing it with normal saline as a filling solution in women with overactive bladder (OAB). Patients and Methods Twenty-three women with significant OAB symptoms underwent consecutive cystometrograms (CMGs) using 0.9% normal saline (NS) and 0.3 M potassium chloride (KCl), the order of which was randomized for each patient. Individual CMGs were performed by separate investigators and both patients and investigators were blinded to the order in which each solution was given and to the results of the other CMG. Results Regardless of the nature of the filling solution, the order in which the CMGs were performed had little influence on either first desire to void (FDV, mean 83.5 ml vs. 117.8 ml for first and second CMGs respectively, P,=,0.10) or on maximum cystometric capacity (Cmax, mean 265.0 ml vs. 264.4 ml, P,=,0.98). KCl produced a significant (24%) reduction in mean Cmax compared to NS (mean 228.6 ml vs. 300.8 ml, P,=,0.001), irrespective of the order of infusion. Conclusion This comparative study using 0.3 M KCl versus NS as filling solutions suggests that intravesical potassium may not simply act on urothelial sensory nerve endings; it may also stimulate detrusor muscle contraction. These findings may influence the interpretation of the potassium sensitivity test in patients with OAB symptoms, particularly in those suspected of having interstitial cystitis. Neurourol. Urodynam. © 2006 Wiley-Liss, Inc. [source] Vision status of children with oculocutaneous albinismOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2002A. O. Oduntan Purpose:, Black South African children with oculocutaneous (OCA) albinism were examined optometrically to establish the level of vision improvement that could be achieved following optical correction. Methods:, The children (N = 153) (males 50.3%; females 49.7%), aged 7,17 years (mean = 10.76 ± 2.25 years) were examined with a logMAR VA chart, cover tests, retinoscopy (dry), subjective refraction, Vistech contrast sensitivity test, ophthalmoscopy, Randot stereotest, Ishihara and Farnsworth Panel D-15 tests. Results:, Many (34.6%) of the children had strabismus, 2,25 prism dioptres. Uncorrected distance VAs were: OD: Finger counting (FC) to 6/7.5 , 2, OS: 6/7.5 + 2 to 6/7.5 , 3, OU: 6/60 , 1 to 6/7.5. Most (67.6%) of the children had myopia. Others (30.8%) had hyperopia or emmetropia (1.7%). Astigmatism was present in 92.25% of the children. The nearest equivalent spherical powers were: OD: ,12.00 to +2.75 D (mean = ,1.48 ± 2.28 D) and OS: ,8.00 to +5. 75 D (mean = 1.36 ± 2.18 D). Following optical correction, VA improvement ranged from one to three lines in 71.2% of the children. The corrected VAs were, OD FC to 6/6 , 1, OS 6/7.5 + 2 to 6/6 , 1, and OU 6/60 to 6/6. Many (84.3%) of the children had corrected VA worse than 6/18 in the better eye and were therefore classified as partially sighted or blind (VA worse than 3/60). Stereoacuity was poor (500,70 sec arc) in most (89.5%) of the children, whilst others could not perceive the minimum 500 sec arc on the test. Contrast sensitivity was poor, maximum spatial frequency being 18 cpd with peak sensitivity at 3 cpd. Many (83%) of the children, however, had normal colour vision. Conclusion:, These children with OCA had poor VA, which could be improved significantly with optical correction. Their poor contrast sensitivity and depth perception, however, were not improved. Most of the children with OCA had normal colour vision. [source] Phase II trial of CoQ10 for ALS finds insufficient evidence to justify phase III,ANNALS OF NEUROLOGY, Issue 2 2009Petra Kaufmann MD Objective Amyotrophic lateral sclerosis (ALS) is a devastating, and currently incurable, neuromuscular disease in which oxidative stress and mitochondrial impairment are contributing to neuronal loss. Coenzyme Q10 (CoQ10), an antioxidant and mitochondrial cofactor, has shown promise in ALS transgenic mice, and in clinical trials for neurodegenerative diseases other than ALS. Our aims were to choose between two high doses of CoQ10 for ALS, and to determine if it merits testing in a Phase III clinical trial. Methods We designed and implemented a multicenter trial with an adaptive, two-stage, bias-adjusted, randomized, placebo-controlled, double-blind, Phase II design (n = 185). The primary outcome in both stages was a decline in the ALS Functional Rating Scale-revised (ALSFRSr) score over 9 months. Stage 1 (dose selection, 35 participants per group) compared CoQ10 doses of 1,800 and 2,700mg/day. Stage 2 (futility test, 75 patients per group) compared the dose selected in Stage 1 against placebo. Results Stage 1 selected the 2,700mg dose. In Stage 2, the pre-specified primary null hypothesis that this dose is superior to placebo was not rejected. It was rejected, however, in an accompanying prespecified sensitivity test, and further supplementary analyses. Prespecified secondary analyses showed no significant differences between CoQ10 at 2,700mg/day and placebo. There were no safety concerns. Interpretation CoQ10 at 2,700mg daily for 9 months shows insufficient promise to warrant Phase III testing. Given this outcome, the adaptive Phase II design incorporating a dose selection and a futility test avoided the need for a much larger conventional Phase III trial. Ann Neurol 2009;66:235,244 [source] New paediatric contrast test: Hiding Heidi low-contrast ,face' testCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 5 2003Clinical Research ABSTRACT Background:,The Hiding Heidi low-contrast ,face' test is a new paediatric contrast test to evaluate the ability to detect objects with low contrast. The purpose of the present study was to compare the Hiding Heidi low-contrast ,face' test (HH) with the Pelli,Robson contrast sensitivity test (PR) and the functional acuity contrast test (FACT) in the low-contrast assessment. Methods:,Thirty university students participated in the present study. The contrast ability was evaluated by using three different methods: HH, PR and FACT. The HH was repeated on two separate occasions to test the repeatability. Results:,There was a significant positive correlation between HH and PR (r = 0.65, P < 0.01); between HH and FACT at 6 cycles per degree (c.p.d.; r = 0.64, P < 0.01); between HH and FACT at 3 c.p.d. (r = 0.91, P < 0.01); and between HH and FACT at 1.5 c.p.d. (r = 0.56, P < 0.01). The paired t -test showed a significant difference between HH and PR (t = ,6.05, P < 0.01); between HH and FACT at 6 c.p.d. (t = ,11.16, P < 0.01); between HH and FACT at 3 c.p.d. (t = ,8.35, P < 0.01); and between HH and FACT at 1.5 c.p.d. (t = ,5.64, P < 0.01). They had good agreement. The HH had a high repeatability. Conclusions:,The HH had a positive correlation but produced significantly different readings when compared with FACT and PR. The features and role of HH in clinical contrast sensitivity assessment are discussed. [source] The assessment of insulin resistance in manDIABETIC MEDICINE, Issue 7 2002T. M. Wallace Abstract Background Insulin resistance exists when a normal concentration of insulin produces a less than normal biological response. The ability to measure insulin resistance is important in order to understand the aetiopathology of Type 2 diabetes, to examine the epidemiology and to assess the effects of intervention. Methods We assess and compare methods of measurement and have undertaken a literature review from 1966 to 2001. Results Quantitative estimates of insulin resistance can be obtained using model assessments, clamps or insulin infusion sensitivity tests. There is considerable variation in the complexity and labour intensity of the various methods. The most well-established methods are the euglycaemic clamp, minimal model assessment and homeostatic model assessment (HOMA). No single test is appropriate under all circumstances. Conclusions There are a number of well-established tests used to measure insulin resistance: the choice of method depends on the size and type of study to be undertaken. Although the so-called ,gold-standard' test, the euglycaemic clamp, is useful for intensive physiological studies on small numbers of subjects, a simpler tool such as HOMA is more appropriate for large epidemiological studies. It is important to be aware that most techniques measure stimulated insulin resistance whereas HOMA gives an estimate of basal insulin resistance. Caution should be exercised when making comparisons between studies due to variations in infusion protocols, sampling procedures and hormone assays used in different studies. [source] Parental Separation and Children's Educational Attainment: A Siblings Analysis on Swedish Register DataECONOMICA, Issue 292 2006ANDERS BJÖRKLUND This paper analyses whether the commonly found negative relationship between parental separation in childhood and educational outcomes is causal or due mainly to selection. We use data on about 100,000 Swedish full biological siblings, born in 1948,63, and perform cross-section and sibling-difference estimations. Outcomes are measured as educational attainment in 1996. Our cross-section analysis shows the expected negative and significant relationship, while the relationship is not significant, though precisely estimated, in the sibling-difference analysis. This finding was robust to the sensitivity tests performed and is consistent with selection, rather than causation, being the explanation for the negative relationship. [source] Theoretical investigation of an energetic fullerene derivativeJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2010Bisheng Tan Abstract A self-consistent estimation method for the thermochemical properties of N -methyl-3-(2,,4,,6,-trinitrobenzene)-fulleropyrrolidine (MTNBFP) is presented. This method is based on enthalpy of formation (,fH) and enthalpy of combustion obtained from BLYP/DNP calculations of the total energies and frequencies for MTNBFP. The enthalpy of formation was calculated by an optimized set of isodesmic reactions given the available experimental ,fH of relative compounds. MTNBFP has a high enthalpy of formation, 2782.2 kJ/mol. Detonation velocity and detonation pressure were also presented in terms of Kamlet and Jacobs equations. Drop hammer impact sensitivity tests and blasting point per 5 s tests indicate MTNBFP may be a potential candidate primary explosive. To understand the test results well, we proposed a series of chemical reaction mechanisms and interpreted the relationship between impact sensitivity and electronic structures from the viewpoint of nitro group charge, electrostatic potential, and vibrational modes. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Relationship Between RDX Properties and SensitivityPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2008Abstract An interlaboratory comparison of seven lots of commercially available RDX was conducted to determine what properties of the nitramine particles can be used to assess whether the RDX has relatively high or relatively low sensitivity. The materials chosen for the study were selected to give a range of HMX content, manufacturing process and reported shock sensitivity. The results of two different shock sensitivity tests conducted on a PBX made with the RDX lots in the study showed that there are measurable differences in the shock sensitivity of the PBXs, but the impact sensitivity for all of the lots is essentially the same. Impact sensitivity is not a good predictor of shock sensitivity for these types of RDX. Although most RDX that exhibits RS has low HMX content, that characteristic alone is not sufficient to guarantee low sensitivity. A range of additional analytical chemistry tests were conducted on the material; two of these (HPLC and DSC) are discussed within. [source] R&D Intensity and Acquisitions in High-Technology Industries: Evidence from the US Electronic and Electrical Equipment IndustriesTHE JOURNAL OF INDUSTRIAL ECONOMICS, Issue 1 2000Bruce A. Blonigen Theory suggests R&D intensity and acquisition activity may be either directly or inversely related. However, we know relatively little about which firms are responsible for acquisition activity in high-technology industries, which are not only R&D-intensive, but also have substantial acquisition activity in the United States. Using a panel of 217 US electronic and electrical equipment firms from 1985,93 and limited dependent variable estimation techniques, we find a substantial negative correlation between R&D-intensity and a firm's propensity to acquire. This result is surprisingly robust to numerous sensitivity tests and is significant in both the ,within' and ,between' dimensions of our data. [source] Application of SSM/I satellite data to a hurricane simulationTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 598 2004Shu-hua Chen Abstract The impact of Special Sensor Microwave/Imager (SSM/I) data on simulations of hurricane Danny is assessed. The assimilation of SSM/I data is found to increase the atmospheric moisture content over the Gulf of Mexico, strengthen the low-level cyclonic circulation, shorten the model spin-up time, and significantly improve the simulation of the storm's intensity. Two different approaches for assimilating SSM/I data, namely assimilating retrieved products and assimilating raw measurements, are further compared. The data-assimilation analyses from these two approaches give different moisture distributions in both the horizontal and vertical directions in the storm's vicinity, which may potentially affect the simulated storm's development; however, the simulated storm intensities are considered comparable for the Danny case. From sensitivity tests performed in this study, it is also found that the choice of the observational error variances could be potentially important to the model simulations. Copyright © 2004 Royal Meteorological Society. [source] FASTEX IOP 18: A very deep tropopause fold.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 577 2001I: Synoptic description, modelling Abstract The life cycle of a very deep tropopause fold (820 hPa) is documented with aircraft and ship observations during the Intensive Observing Period 18 of the Fronts and Atlantic Storm-Track EXperiment (FASTEX). The initial setting involves a coherent tropopause disturbance and an associated Arctic tropopause fold. The confluence episode that results from the phasing up of the tropopause disturbance and a southern ridge, ends in the formation of an intense jet streak, the dynamics of which are associated with the development of a polar tropopause fold. A diagnostic analysis suggests that the final dramatic stratospheric intrusion is the consequence of the vertical superposition of the Arctic and polar tropopause folds. The Mesoscale Non-Hydrostatic (Meso-NH) model is used to discuss this hypothesis. Mixing of the passive stratospheric tracer within the marine boundary layer is investigated with sensitivity tests which unplug, in turn, the model physical parametrizations. Finally, upper-level forcings associated with the development of the tropopause fold are investigated in detail in a companion paper. [source] GM3 synthase gene is a novel biomarker for histological classification and drug sensitivity against epidermal growth factor receptor tyrosine kinase inhibitors in non-small cell lung cancerCANCER SCIENCE, Issue 10 2007Mariko Noguchi Expression of gangliosides and alterations in their composition have been observed during cell proliferation and differentiation and in certain cell cycle phases, brain development and cancer malignancy. To investigate the characteristics of GM3 synthase, SAT-I mRNA and ganglioside GM3 expression levels in lung cancer, we examined the expression levels of SAT-I mRNA as well as GM3 in 40 tumor tissues surgically removed from non-small cell lung cancer patients. Adenocarcinoma tissues expressed SAT-I mRNA levels that were significantly higher than those of squamous and other carcinomas (P < 0.0001). Moreover, the SAT-I mRNA levels were high in the bronchioalveolar carcinoma subtype and low in the solid and mucin subtypes of adenocarcinomas (P = 0.049, 0.049 and 0.013, respectively). To clarify the relationship between SAT-I mRNA and epidermal growth factor receptor (EGFR)-tyrosine kinase (TK) inhibitor sensitivity, we carried out drug sensitivity tests for the EGFR-TK inhibitors gefitinib and AG1478 using eight adenocarcinoma cell lines expressing no EGFR mutations. The IC50 values for gefitinib and AG1478 decreased dramatically with increasing SAT-I mRNA levels (R2 = 0.81 and 0.59, respectively), representing a wide range of drug sensitivities among adenocarcinoma cell lines. To explore a possible mechanism of how GM3 could enhance the sensitivity to EGFR-TK inhibitors, the SAT-I gene was introduced stably into a GM3-negative clone of murine 3LL lung cancer cells to produce GM3-reconstituted clones. We found an increase in EGFR protein levels and gefitinib sensitivity in GM3-reconstituted cells, suggesting the involvement of GM3 in the turnover of EGFR protein. Therefore, it is highly expected that, by measuring the expression levels of SAT-I mRNA in lung biopsy samples from non-small cell lung cancer patients, enhanced pathological identification and individualized chemotherapeutic strategies can be established for the appropriate use of EGFR-TK inhibitors. (Cancer Sci 2007; 98: 1625,1632) [source] | ||||||||||||||||||||||