Current-mode integrator for voltage-controllable low frequency continuous-time filters

A novel differential current-mode integrator (CMI) for voltage-controllable low frequency continuous-time filters is presented. An example fifth-order lowpass filter using the proposed CMI and on-chip capacitors was implemented in an AMI 1.2 /spl mu/m CMOS process, and it achieved -3 dB cutoff frequencies ranging from 160 Hz to 5.6 kHz, by changing a single control voltage.     

Electrochemical oxidation of adsorbed alkenoic acids as a function of chain length at Pt(111) electrodes. Studies by cyclic voltammetry,EELS and Auger spectroscopy

Studies of the electrochemical oxidation of a series of straight-chain terminal alkenoic acids adsorbed at a Pt(111) electrode surface are reported. Compounds adsorbed were: propenoic acid (acrylic acid, PPA); 3-butenoic acid (vinylacetic acid, 3BTA); 4-pentenoic acid (allylacetic acid, 4PTA); 6-heptenoic acid (6HPA); and 10-undecenoic acid (10UDA). Vibrational spectra of adsorbed layers were obtained by use of electron energy-loss spectroscopy (EELS). Molecular packing densities were measured by use of Auger spectroscopy. Electrochemical oxidation of each adsorbed layer was explored by means of cyclic voltammetry in aqueous inert electrolyte (KF/HF). As the analogous aliphatic acids are not chemisorbed at Pt under the same conditions, the alkenoic acids evidently adsorb at Pt(111) predominantly through the C=C double bond. Molecular packing densities indicate that the carboxylic acid moiety is in contact with the Pt surface only in the case of PPA. EELS spectra also indicate that the carboxylate groups (other than in PPA) are present as pendants. The carboxylic acid O-H stretching bands of most of the adsorbed acids are red-shifted and broadened, evidently due to extensive intermolecular hydrogen bonding; the exceptions are PPA, for which the interaction is primarily with the Pt surface, and 3BTA, for which intermolecular interaction between the carboxylic acid pendants is apparently prevented by steric considerations. The surface-attached carboxylic acid moieties react with KOH solution, leading to retention of K⁺ ions, detected by Auger spectroscopy, and to changes in the vibrational spectra indicative of carboxylate anions; reactivity toward KOH decreases with chain length. Adsorbed alkenoic acids at Pt(111) surfaces are stable in water and in vacuum. Oxidation of the adsorbed short-chain acids PPA and 3BTA proceeds to completion, forming CO₂ as the principal product. Oxidation of the adsorbed long-chain acids converts the C=C moiety to 2CO₂, and transforms the remainder of the molecule to an unadsorbed diacid (likely possibilities are malonic acid from 4PTA; glutaric acid from 6HPA; and heptane-1,7-dioic acid from 10UDA).     

Survival in patients with cryptogenic fibrosing alveolitis: a population-based cohort study

STUDY OBJECTIVES: To determine the median survival of patients with cryptogenic fibrosing alveolitis, in comparison to that expected of individuals of the same age and sex from the general population. To estimate the effect of survival bias incurred by studying both incident and prevalent cases. To identify factors associated with survival. DESIGN: Cohort study. SETTING: Nine hospitals from the Trent Region of England. PATIENTS: Two hundred forty-four cases of cryptogenic fibrosing alveolitis: 168 patients were alive on day 1 of the study (prevalent cases), and 76 patients had newly diagnosed conditions over a prospective 18-month period of patient recruitment (incident cases). MEASUREMENTS: Age, sex, date of diagnosis, lung function at presentation, and details of treatment prescribed were extracted from hospital clinical records. Data on lifetime smoking habits were collected by postal questionnaire. Vital status was established from the general practitioner. The expected survival of each case was extracted from the English life tables. RESULTS: Median survival for incident cases was 2.9 years and for prevalent cases 9 years, compared to expected values of 10 and 13 years, respectively. Incident cases had significantly worse survival than prevalent cases, even after adjustment for the effects of age, sex, smoking history, lung function at presentation, and treatment (hazard ratio, 4.53 [95% confidence interval, 2.71 to 7.56]; p<0.001). Lower FVC at presentation and the use of corticosteroid treatment were both associated with worse survival. CONCLUSIONS: The inclusion of prevalent cases leads to significant overestimation of the median survival for patients with cryptogenic fibrosing alveolitis. In newly diagnosed cases of cryptogenic fibrosing alveolitis, median survival is only 2.9 years, and expected life span is reduced by approximately 7 years.     

Impact of employee mobility and employee performance on the allocation of rewards under conditions of constraint.

We advanced and tested a multiple-motive model of resource allocation. In this model we identified importance instrumental, social-emotional, and group maintenance goals, and asserted that rational managers will sometimes allocate reduced rewards to employees with constrained mobility. Consistent with predictions, managers allocated greater salary funds to more deserving employees: those with high competence and dedication. However, allocations also differed as a function of employee mobility. This effect was strongest among competent employees, whose membership was most desirable. Furthermore, the tendency to allocate lesser rewards to low-mobility employees was particularly pronounced under conditions of low reward availability and low labor availability. These effects were not mediated by changes in perceptions of the competence of low-mobility employees. These findings are discussed as a form of rational selective exploitation: The rational manager's need to attend to employee mobility, particularly under conditions of reward or labor constraint, may erode equity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

TINUVIN XT 833在PVC防水卷材中的应用

对Tinuvin XT 833改善聚氯乙烯防水卷材的耐候性能方面进行了研究，并与Chimassorb 81和Tinuvin 329进行了比较。结果表明，Tinuvin XT 833在软质聚氯乙烯拉伸断裂伸长率的保持率方面比Chimassorb 81和Tinuvin 329更加有效，与传统的光稳定剂相比，它能大幅度地延长聚氯乙烯防水卷材的使用寿命，应用在不同的配方体系，都能将聚氯乙烯防水卷材的使用寿命提高一倍以上，并能适用于许多户外使用的聚氯乙烯软制品。     

A practical approach to evaluating test results

The author describes the procedure used at NCR Corporation to evaluate the data collected during usability tests. He points out that it can be overwhelming to face a mass of data to be compiled, categorized, analyzed, and evaluated at the end of a test, with limited time available for producing a report. This situation is avoided by defining, before a test, the tools that will be used to collect the test data and the process by which the results will be evaluated, and then performing the preliminary evaluation of data in a process parallel with the test itself. At the end of the test, an evaluation meeting is held at which the cumulative results are reviewed and solutions to the problems that have been identified are defined     

Leucocyte and endothelial cell adhesion molecule expression in porcine histiocytic leiomyofibrosarcoma

A histiocytic sarcoma was present at birth in a pig. On the basis of ultra-structure and structural-protein composition (presence of alpha-smooth-muscle actin but not keratin), the sarcoma component was identified as a leiomyofibrosarcoma. Lipid-laden macrophages (histiocytes), which permeated the tumour in an apparently random fashion, were somewhat atypical in that they were negative for some macrophage markers; they gave a reaction, however, for CDw14. Despite its aggressive metastatic capacity, this tumour occurred almost exclusively in the subcutis, dermis and skeletal muscle. The tumour was extensively vascularized with many small capillaries which did not express E-selectin (CD69E), MHC class II or the L-selectin (CD69L) ligand, markers characteristic of inflamed (activated) endothelial cells in pig skin. Significant numbers of the histiocytes were positive for the integrins CD18 and VLA-4 (CD49d), indicating involvement of integrin pathways in the spread or growth, or both, of the leiomyofibrosarcoma. Most of the fibrous sarcoma cells also had extensive reactivity with an antibody to the standard variant form of CD44 (CD44s).     

Role of glial filaments in cells and tumors of glial origin: a review

In the adult human brain, normal astrocytes constitute nearly 40% of the total central nervous system (CNS) cell population and may assume a star-shaped configuration resembling epithelial cells insofar as the astrocytes remain intimately associated, through their cytoplasmic extensions, with the basement membrane of the capillary endothelial cells and the basal lamina of the glial limitans externa. Although their exact function remains unknown, in the past, astrocytes were thought to subserve an important supportive role for neurons, providing a favorable ionic environment, modulating extracellular levels of neurotransmitters, and serving as spacers that organize neurons. In immunohistochemical preparations, normal, reactive, and neoplastic astrocytes may be positively identified and distinguished from other CNS cell types by the expression of the astrocyte-specific intermediate filament glial fibrillary acidic protein (GFAP). Glial fibrillary acidic protein is a 50-kD intracytoplasmic filamentous protein that constitutes a portion of, and is specific for, the cytoskeleton of the astrocyte. This protein has proved to be the most specific marker for cells of astrocytic origin under normal and pathological conditions. Interestingly, with increasing astrocytic malignancy, there is progressive loss of GFAP production. As the human gene for GFAP has now been cloned and sequenced, this review begins with a summary of the molecular biology of GFAP including the proven utility of the GFAP promoter in targeting genes of interest to the CNS in transgenic animals. Based on the data provided the authors argue cogently for an expanded role of GFAP in complex cellular events such as cytoskeletal reorganization, maintenance of myelination, cell adhesion, and signaling pathways. As such, GFAP may not represent a mere mechanical integrator of cellular space, as has been previously thought. Rather, GFAP may provide docking sites for important kinases that recognize key cellular substrates that enable GFAP to form a dynamic continuum with microfilaments, integrin receptors, and the extracellular matrix.     

Unilateral nasal allergen challenge leads to bilateral release of prostaglandin D2

BACKGROUND: Multiple mediators including prostaglandin D2 and leukotriene B4 have been shown to increase in nasal secretions during the early response to nasal challenge with antigen. OBJECTIVE: Our objective was to investigate the time course of prostanoid and leukotriene B4 release into nasal secretions on both the ipsilateral and contralateral side after a unilateral nasal allergen challenge. METHODS: We performed a controlled, randomized trial. Six volunteers were challenged unilaterally with antigen or diluent in a randomized order and discs were used to collect nasal secretions from both nostrils at 2 min intervals for 20 min after the challenge. Prostanoids and leukotriene B4 (LTB4) in recovered nasal secretions were measured by combined capillary gas chromatography-negative ion chemical ionization mass spectrometry (GC/MS). RESULTS: Nasal allergen challenge resulted in a significant and immediate increase in symptoms and sneezing. PGD2 was significantly elevated above diluent values (0.6 +/- 0.6 pg) 30 s after removal of the allergen disc (P < 0.05), reached its peak (423.2 +/- 182.4 pg) at 2 min and then slowly decreased. PGD2 also increased on the contralateral side after unilateral allergen challenge, reaching peak values about six times lower than on the ipsilateral side (70.8 +/- 21.7 pg at 6 min). Levels of 9a, 11b-PGF2 after antigen provocation became significantly higher than after diluent (0 +/- 0 pg) on the ipsilateral side at 2 min (17.2 +/- 5.9 pg), and reached peak levels at 4 min (25.1 +/- 8.0 pg). LTB4 also increased significantly on the side of challenge. For the other prostanoids measured (PGF2, PGF2 alpha, TxB2, 6kPGF1 alpha), no significant changes in either ipsilateral or contralateral secretions were observed after allergen challenge. CONCLUSIONS: Our study described the kinetics of PGD2 and LTB4 release as well as the contralateral release of PGD2.