1,731 research outputs found

    Phase Distribution and Phase Correlation of Financial Time Series

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    Scaling, phase distribution and phase correlation of financial time series are investigated based on the Dow Jones Industry Average (DJIA) and NASDAQ 10-minute intraday data for a period from Aug. 1 1997 to Dec. 31 2003. The returns of the two indices are shown to have nice scaling behaviors and belong to stable distributions according to the criterion of Levy's alpha stable distribution condition. A novel approach catching characteristic features of financial time series based on the concept of instantaneous phase is further proposed to study phase distribution and correlation. The analysis of phase distribution concludes return time series fall into a class which is different from other non-stationary time series. The correlation between returns of the two indices probed by the distribution of phase difference indicates there was a remarkable change of trading activities after the event of 911 attack, and this change persisted in later trading activities.Phase Distribution, High Frequency Data, Scaling Analysis, Levy Distribution, Stock Market, Frequency Variant

    Low Polarization Voltage and High Sensitivity CMOS Condenser Microphone Using Stress Relaxation Design

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    AbstractIn this paper, a CMOS condenser microphone with high sensitivity and low polarization voltage was designed, simulated and fabricated. Due to CMOS process temperature variant and lattice defects, the poly-membrane would be invoked normal stress and gradient stress. These two residual stresses would deform the membrane and increase the membrane's rigidity. For these concerns, an interlace slots design is utilized to reduce the normal stress up to 90%, and the annealing process is applied to decrease the gradient stress. The acoustical sensitivity was increased considerably to -45dBV at 2.7V bias voltage, and, the noise level is -85dBV at 1KHz

    Evaluation of Risk Factors for Asthma in Taipei City

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    BackgroundAsthma has rarely been studied by evaluating all of its trigger factors in 1 study population. Thus, correlations between the concentration of allergen immunoglobulin (Ig) E antibodies and airway limitation or asthma severity remain unclear.MethodsFive hundred and seventy-nine asthmatic patients were enrolled, and serum specific IgE antibodies to allergens were analyzed. All suspected trigger factors were assessed by questionnaire, case histories over a 4-year period, and diary card recordings; possible trigger factors were then re-evaluated.ResultsAntibodies to the following allergens were found: Dermatophagoides pteronyssinus (59.8% of patients), D. microceras (58.8%), D. farinae (56.8%), cockroach (38.3%), dog dander (26.3%), Candida albicans (13.3%), cat dander (10%), and Cladosporium herbarum (6.6%). A greater prevalence of allergy to dog and cat dander was found than previously. Younger patients were more often positive for mite allergens, and had higher titers of antibodies against such allergens, than older patients. Further, females had a lower concentration of mite allergen antibodies than males. No correlation between the concentration of allergen antibodies and forced expiratory volume in 1 second (FEV1), or the ratio of FEV1:forced vital capacity (FEV1:FVC), was found. In addition, there was no significant change in antibody titers with varying asthma severity. Non-allergenic trigger factors were irritant air inhalants (94.6% of patients), respiratory infection (92.2%), exercise (75.2%), emotional factors (58.8%), drugs and chemical substances (16%).ConclusionThere are multiple trigger factors in asthma. Allergenic trigger factors are more common in younger than older patients, whereas non-allergenic trigger factors are more common in older patients. There was no linear correlation between the concentration of specific IgE antibodies and asthma severity or airway limitation; therefore, to prevent asthma attacks in individual asthmatic patients, greater attention should be paid to avoiding all potential trigger factors, and not just house dust mite allergens

    Areca Users in Combination with Tobacco and Alcohol Use Are Associated with Younger Age of Diagnosed Esophageal Cancer in Taiwanese Men

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    BACKGROUND: Whether the habitual use of substances (tobacco, alcohol, or areca nut (seed of the Areca palm)) can affect the age of esophageal squamous cell carcinoma (ESCC) presentation has rarely been examined. METHODS: The study subjects were those who were males and the first time to be diagnosed as ESCC (ICD-9 150) and who visited any of three medical centers in Taiwan between 2000 and 2009. A standardized questionnaire was used to collect substance uses and other variables. RESULTS: Mean age (±SD) at presentation of ESCC was 59.2 (±11.3) years in a total of 668 cases. After adjusting for other covariates, alcohol drinkers were 3.58 years younger to have ESCC than non-drinkers (p = 0.002). A similar result was found among areca chewers, who were 6.34 years younger to have ESCC than non-chewers (p<0.0001), but not among cigarette smokers (p = 0.10). When compared to the group using 0-1 substances, subjects using both cigarettes and alcohol were nearly 3 years younger to contract ESCC. Furthermore, those who use areca plus another substance were 7-8 years younger. Subjects using all three substances had the greatest age difference, 9.20 years younger (p<0.0001), compared to the comparison group. CONCLUSION: Our findings suggest that habitually consuming tobacco, alcohol, and areca nut can influence the age-onset of ESCC. Since the development of ESCC is insidious and life-threatening, our observation is worthy to be reconfirmed in the large-scale and long-term follow-up prospective cohort studies to recommend the screening strategy of this disease

    A huge traumatic pulmonary pseudocyst

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    AbstractTraumatic pulmonary pseudocyst (TPP) is a rare complication following blunt trauma. We report a 26-year-old male patient who presented to the emergency room with internal bleeding and shock. Huge TPP (14 cm in diameter) was seen on whole-body computed tomography scan and complicated with bronchial bleeding. He deteriorated to respiratory failure soon after arriving at the emergency room. TPPs imply high-energy impact on the chest region and frequently complicated with pulmonary contusions, hemo- and pneumo-thorax, multiple rib fractures, flail chest, and concurrent with abdominal injuries. Emergency physicians should be aware of such rare entity and manage correctly

    Exploring the Impacts of Web-Based e-Procurement on Organizational Performance

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    Web-enabled applications for business-to-business (B2B) procurement are not only expected to reduce the cost of purchasing process but also to alter the activities of purchasing, transform the purchasing process from an operational into a strategic activity, and provide opportunities for improving market coordination by reducing asset specificity and by making additional partners available. From organizational and inter-organizational perspectives, this study proposes a performance impact model of implementing Web-based e-procurement system for direct procurement. In the performance impact model, the strategic dimension is about partner relationship, and the operational efficiency dimension includes supplier performance, buyer performance, process integration, and process automation. Based on a survey of Taiwanese manufacturing firms, the results of this study show that the electronic execution of purchasing activities improves both of the operational efficiency dimension and the strategic dimension. The results demonstrate implementing Web-based e-procurement system not only could enhance the performance of the buyer organization but also could enhance the performance of the supplier organization and improve partner relationship management

    Spontaneous Dissecting Aneurysm of the Renal Artery: A Case Report

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    Primary dissecting aneurysms of the renal artery are exceedingly rare. The triad of flank pain, hematuria, and hypertension of acute onset in the absence of urinary obstruction should suggest this rare condition. We report a case of spontaneous dissecting aneurysm of the renal artery treated using conservative medical treatment. The diagnosis, therapeutic management, and outcome are discussed
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