A total least squares proximal support vector classifier for credit risk evaluation

In this paper, a total least squares (TLS) version of proximal support vector machines (PSVM) is proposed for credit risk evaluation. The formulation of this new model is different from the original PSVM model, so a novel iterative algorithm is proposed to solve this model. A simulation test is first implemented on a classic two-spiral dataset, and then an empirical experiment is conducted on two publicly available credit datasets. The experimental results show that the proposed total least squares PSVM (TLS-PSVM) is at least comparable with PSVM and better than other models including standard SVM model.     

枞树型核电轮槽精铣刀制造技术优化设计

以枞树型叶根精铣刀为例,阐述了可换硬质合金型线刀体和刀片精铣刀的优化设计、制造工艺、建模及优化设计,进行切削过程加工策略优化和加工过程模拟,设计制造了锥柄专用工装及检测环规、磨削刀片后角专用工装,采用NUMROTO软件编制刀片加工工步。该项目研制的可换刀片精铣刀型线精度完全能达到进口铣刀水平,能满足大部分轮槽与叶根加工对型线精度的要求,可以大幅度节约刀具费用。     

Progress in CdZnTe substrate producibility and critical drivers of IRFPA yield originating with CdZnTe substrates

With the goal of maximizing the yield of infrared focal plane arrays (IRFPAs), Santa Barbara Research Center’s (SBRC) Infrared Materials Producibility Program (IRMP) has focused on assessing and improving the quality, yield, and throughput of CdZnTe substrates. A baseline detector lot was fabricated to identify the critical drivers of IRFPA yield coming from the substrates and to evaluate the quality and yield of the current vendor base for CdZnTe substrates. Substrate induced defects and impurities that can potentially affect device performance and operability were carefully mapped out in detail on 44 × 67 mm² size substrates, received from IRMP substrate vendors as well as SBRC. This paper will report on the correlations found between this substrate characterization data base and the IRFPA level defect distributions. Key results from these correlation studies are: (1) extended defects found on the substrates with the Nakagawa etch correlated well with responsivity reduction in the final IRFPA; (2) cross-hatch patterns that were evident in the responsivity map correlated well with similar features seen by x-ray topography on LPE double layers; and (3) a possible correlation of device performance (leakage current at 78K) with copper and lithium impurities in the substrate. Recent initiatives toward improving the quality and yield of the substrate growth process have focused on improving purity in the pre-growth charge preparation, modification of growth parameters to reduce defects and scaling up of the vertical Bridgman growth process from its current 67 mm diameter boule size to 92 mm diameter boules. Promising initial results from the large diameter boule growth process will be shown. The 92 mm diameter CdZnTe boule (6 kg charge) shows two predominant single crystal grains encompassing 75% of boule volume. Defect characterization of boules grown under baseline and modified conditions is discussed.     

Development of a Highly Selective,Sensitive, and Fast Response Upconversion Luminescent Platform for Hydrogen Sulfide Detection

Hydrogen sulfide (H₂S) has been recognized as one of most important gaseous signaling molecules mediated by a variety of physiological and pathological processes. Yet, its functions remain largely elusive due to the lack of potent monitoring methods. Hereby this issue is addressed with a powerful new platform—dye‐assembled upconversion nanoparticles (UCNPs). A series of chromophores with different absorption bands and fast responses towards H₂S is combined with UCNPs and results in a library of H₂S sensors with responsive emission signals ranging from the visible to the near‐infrared (NIR) region. These nanoprobes demonstrate highly selective and rapid responses to H₂S in vitro and in cells. Furthermore, H₂S levels in blood can be detected using the developed nanoprobes. Hence the reported H₂S sensing platform can serve as a powerful diagnostic tool to research H₂S functions and to investigate H₂S‐related diseases.     

己二酸的清洁催化氧化合成研究进展

综述了近年来以环己烯、环己酮、环己醇或环己烷等作原料,以过氧化氢或氧气等为氧源,采用不同的催化体系清洁合成己二酸的新进展.指出:在这些方法中,改性的分子筛及负载型催化剂-双氧水体系将是今后己二酸清洁合成的重点研究方向.     

Continuous analysis of dissolved gaseous mercury (DGM) and mercury flux in two freshwater lakes in Kejimkujik Park,Nova Scotia: evaluating mercury flux models with quantitative data

Diurnal patterns for dissolved gaseous mercury (DGM) concentration, mercury flux, several water variables (pH, oxidation reduction potential (ORP), water temperature), and meteorological variables (wind speed, air temperature, % relative humidity, solar radiation) were measured in two lakes with contrasting dissolved organic carbon (DOC) concentrations in Kejimkujik Park, Nova Scotia. A continuous analysis system made it possible to measure quick changes in DGM over time. Consistently higher DGM concentrations were found in the high DOC lake as compared to the low DOC lake. An examination of current mercury flux models using this quantitative data indicated some good correlations between the date and predicted flux (r ranging from 0.27 to 0.83) but generally poor fit (standard deviation of residuals ranging from 0.97 to 3.39). Cross-correlation analysis indicated that DGM dynamics changed in response to solar radiation with lag-times of 65 and 90 min. This relationship with solar radiation was used to develop new predictive models of DGM and mercury flux dynamics for each lake. We suggest that a generalized approach using time-shifted solar radiation date to predict DGM can be incorporated into existing mercury flux models. It is clear from the work presented that DOC and wind speed may also play important roles in DGM and mercury flux dynamics, and these roles have not been adequately accounted for in current predictive models.     

In vitro availability of starch in heat‐treated potatoes as related to genotype,weight and storage time

The objective of the study was to determine the influence of potato variety, weight and storage time after lifting on the glycaemic index (GI) and resistant starch (RS) content predicted from measurement of the rate and extent of in vitro starch hydrolysis, respectively. The potatoes were either boiled, or boiled and subjected to different heat‐cycling conditions selected to promote retrogradation of amylose or amylopectin, respectively. The hydrolysis indices (HI) and predicted GIs of all 19 potato products were high and fell within narrow ranges of 122–144 and 118–138, respectively. No correlation between average weight of the potato tuber and HI was found. Furthermore, there was no difference in HI between potatoes stored for 1–3 or 8–10 months, nor between varieties of new potato and winter potato. However, the HI was significantly lowered by temperature cycling at conditions known to promote retrogradation of amylopectin (6 °C, 48 h) compared with 6 °C for 24 h followed by 70 °C for 24 h. RS content was already substantial in boiled potatoes, 4.5 g 100 g^?1 (starch basis), and could be increased further by temperature cycling, the highest yield obtained, 9.8 g 100 g^?1 (starch basis), following heat treatment at 6 °C for 24 h followed by 70 °C for 24 h; that is at conditions known to favour amylose retrogradation. Copyright © 2004 Society of Chemical Industry     

O6-alkylguanine-DNA alkyltransferase inactivation by ester prodrugs of O6-benzylguanine derivatives and their rate of hydrolysis by cellular esterases

To modulate the bioavailability and perhaps improve the tumor cell selectivity of O6-alkylguanine-DNA alkyltransferase (AGT) inactivators, pivaloyloxymethyl ester derivatives of O6-benzylguanine (BG) were synthesized and tested as AGT inactivators and as substrates for cellular esterases. The potential prodrugs examined were the 7- and 9-pivaloyloxymethyl derivatives of O6-benzylguanine (7- and 9-esterBG), and of 8-aza-O6-benzylguanine (8-aza-7-esterBG and 8-aza-9-esterBG) and the 9-pivaloyloxymethyl derivative of 8-bromo-O6-benzylguanine (8-bromo-9-esterBG). The benzylated purines were all potent inactivators of the pure AGT and of the AGT activity in HT29 cells and cell extracts. Each ester was at least 75 times less potent than the corresponding benzylated purine against the pure human AGT. In contrast, the activities of esters and their respective benzylated purine were similar in crude cell extracts and in intact cells. The increase in potency of esters in cellular extracts could be explained by a conversion of the respective prodrug to the more potent benzylated purine in the presence of cellular esterases. The apparent catalytic activity (Vmax/Km) of liver microsomal esterase for 8-azaBG ester prodrugs was 70-130 times greater than for BG prodrugs and 10-20 times greater than for 8-bromo-9-esterBG. Tumor cell hydrolysis of the esters varied considerably as a function of cell type and prodrug structure. These data suggest that these or related prodrugs may be advantageous for selective AGT inactivation in certain tumor types.     

Five days of oral topotecan (Hycamtin), a phase I and pharmacological study in adult patients with solid tumours

Topotecan is a specific inhibitor to topoisomerase I. An oral formulation of topotecan is available with a bioavailability of 32-44% in humans. A phase I and pharmacological study of the oral formulation of topotecan administered daily for 5 days every 21 days was performed in adult patients with solid tumours to determine the maximum tolerated dose (MTD). Adult patients with a WHO performance status < or = 2 adequate haematological, hepatic and renal functions, with malignant solid tumours refractory to standard forms were entered into the study. Pharmacokinetics were performed on days 1 and 4 of the first course using a validated high performance liquid chromatographic assay. 29 patients entered the study, all patients were evaluable for toxicity and response. The doses studied in the 29 patients were 1.2, 1.8, 2.3, 2.7 mg/m2/day and a fixed dose of 4 mg/day without surface area adjustment. A total of 109 courses were given. Dose limiting toxicity (DLT) was reached at a dose of 2.7 mg/m2/day and consisted of CTC (NCI-Common Toxicity Criteria) grade IV granulocytopenia. The regimen was well tolerated. Non-haematological toxicities were mild, including fatigue, anorexia, nausea, vomiting and diarrhoea. A significant correlation was observed between the percentage decrease in white blood cells versus the area under the curve (AUC(t)) of topotecan lactone (R = 0.76 P < 0.01) which was modelled by a sigmoidal Emax function. The correlation coefficient between the absolute topotecan dose administered and the AUC(t) was R = 0.52 (P = 0.04). Pharmacokinetics of the fixed dose of 4 mg/day were comparable to the 2.3 mg/m2/day dose. DLT in this phase I study of five daily doses of oral topotecan every 21 days was granulocytopenia. The recommended dose for phase II studies is 2.3 mg/m2/day or alternatively, a fixed dose of 4 mg/day.     

Long-term outcome after marrow transplantation for severe aplastic anemia

We reviewed the records and reevaluated 212 patients with aplastic anemia transplanted at the Fred Hutchinson Cancer Research Center (FHCRC) between 1970 and 1993 who survived >/=2 years and who have been followed for up to 26 years. Parameters analyzed included hematopoietic function, chronic graft-versus-host disease (GVHD), skin disease, cataracts, lung disease, skeletal problems, posttransplant malignancy, depression, pregnancy/fatherhood, and the return to work or school, as well as patient self-assessment of physical and psychosocial health, social interactions, memory and concentration, and overall severity of symptoms. Survival probabilities at 20 years were 89% for patients without (n = 125) and 69% for patients with chronic GVHD (n = 86) (the status was uncertain in 1 surviving patient). All patients had normal hematopoietic parameters. Skin problems occurred in 14%, cataracts in 12%, lung disease in 24%, and bone and joint problems in 18% of patients. Eleven patients (12%) developed a solid tumor malignancy and 19% of patients experienced depression. Chronic GVHD was the dominant risk factor for late complications. Seventeen patients died at 2.5 to 20.4 years posttransplant; 13 of these had chronic GVHD and related complications. At 2 years, 83% of patients had returned to school or work; the proportion increased to 90% by 20 years. At least half of the patients preserved or regained the ability to become pregnant or father children. Patients rated their quality of life as excellent and symptoms as minimal or mild. In conclusion, marrow transplantation in patients with aplastic anemia established long-term normal hematopoiesis. No new hematologic disorders occurred. The major cause of morbidity and mortality was chronic GVHD. However, the majority of patients who survived beyond 2 years returned to a fully functional life.