41 research outputs found

    Gas-Phase Temperature Mapping of Evaporating Microdroplets

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    Evaporation is a ubiquitous and complex phenomenon of importance to many natural and industrial systems. Evaporation occurs when molecules near the free interface overcome intermolecular attractions with the bulk liquid. As molecules escape the liquid phase, heat is removed, causing evaporative cooling. The influence of evaporative cooling on inducing a temperature difference with the surrounding atmosphere as well as within the liquid is poorly understood. Here, we develop a technique to overcome past difficulties encountered during the study of heterogeneous droplet evaporation by coupling a piezo-driven droplet generation mechanism to a controlled micro-thermocouple to probe microdroplet evaporation. The technique allowed us to probe the gas-phase temperature distribution using a micro-thermocouple (50 mu m) in the vicinity of the liquid-vapor interface with high spatial (+/- 10 mu m) and temporal (+/- 100 ms) resolution. We experimentally map the temperature gradient formed surrounding sessile water droplets having varying curvature dictated by the apparent advancing contact angle (100 degrees less than or similar to theta less than or similar to 165 degrees). The experiments were carried out at temperatures below and above ambient for a range of fixed droplet radii (130 mu m less than or similar to R less than or similar to 330 mu m). Our results provide a primary validation of the centuries-old theoretical framework underpinning heterogeneous droplet evaporation mediated by the working fluid, substrate, and gas thermophysical properties, droplet apparent contact angle, and droplet size. We show that microscale droplets residing on low-thermal-conductivity substrates such as glass absorb up to 8x more heat from the surrounding gas compared to droplets residing on high-thermal-conductivity substrates such as copper. Our work not only develops an experimental understanding of the heat transfer mechanisms governing droplet evaporation but also presents a powerful platform for the study and characterization of liquid-vapor transport at curved interfaces wetting and nonwetting advanced functional surfaces

    Measuring downstream supply chain performance using Bayesian networks

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    Increase of costs and complexities in organizations beside the increase of uncertainty and risks have led the managers to use the risk management in order to decrease risk taking and deviation from goals. During the years different methods have been used by researchers in order to manage supply chain risk but most of them are qualitative. On the other hand just in few quantitative models, the effects of risks on each other have been not evaluated. In this paper the risk metrics will be modeled in downstream supply chain which is a part of chain related to sale, distribution and products' costumers. First qualitative assessment will be done by recognizing risk metrics of supply chain model and then by combining qualified and quantified metrics, downstream supply chain performance will be measured and key factors will be recognized. Total cost is the most important factor and production cost is the most important criteria which can affect downstream supply chain performance. Also style change between criteria has the least impact and importance. Finally through a case study example, the performance and validation of proposed model will be presented.</p

    The Use of Data from the Parkinson's KinetiGraph to Identify Potential Candidates for Device Assisted Therapies

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    Device-assisted therapies (DAT) benefit people with Parkinsons Disease (PwP) but many referrals for DAT are unsuitable or too late, and a screening tool to aid in identifying candidates would be helpful. This study aimed to produce such a screening tool by building a classifier that models specialist identification of suitable DAT candidates. To our knowledge, this is the first objective decision tool for managing DAT referral. Subjects were randomly assigned to either a construction set (n = 112, to train, develop, cross validate, and then evaluate the classifier's performance) or to a test set (n = 60 to test the fully specified classifier), resulting in a sensitivity and specificity of 89% and 86.6%, respectively. The classifier's performance was then assessed in PwP who underwent deep brain stimulation (n = 31), were managed in a non-specialist clinic (n = 81) or in PwP in the first five years from diagnosis (n = 22). The classifier identified 87%, 92%, and 100% of the candidates referred for DAT in each of the above clinical settings, respectively. Furthermore, the classifier score changed appropriately when therapeutic intervention resolved troublesome fluctuations or dyskinesia that would otherwise have required DAT. This study suggests that information from objective measurement could improve timely referral for DAT

    Collecting vaginal discharge with or without speculum in diagnosing gynecological infections

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    BackgroundCurrently, with the omission of speculum in vaginal examination, noninvasive methods to diagnose gonorrhea and chlamydia by urine tests are available. It is now possible to diagnose bacterial vaginosis, candidiasis and trichomoniasis by vaginal swabs directly without speculum examination.  PurposeThis quasi-experimental study was conducted to compare the results of two sampling methods with or without speculum of vaginal discharge in diagnosing gynecological infections. Methods100 patients between 18-49 with vaginal discharge and other manifestations of vaginosis referring to gynecology clinic of Taleghani hospital were selected by convenience sampling method. One vaginal swab was used before examination with speculum and one during it to collect the discharge for diagnosing trichomoniasis, candidiasis and bacterial vaginosis. Both samples were observed under microscope by blind method and compared in terms of sensitivity. ResultsSensitivities of discharge collection with and without speculum for diagnosing bacterial vaginosis, trichomoniasis and candidiasis were %81 and %71, 69% and %62.5, and %86 and %77 respectively with no significant difference. Agreements between the two methods for the diagnosis of bacterial vaginosis, trichomoniasis and candidiasis were 0.89, 0.85 and 0.72 respectively. ConclusionGynecological infections can be detected without examination by speculum. This is helpful for those who fear from this type of examination and delay their visits.  Keywords: Gynecological infections, Sexually transmitted disease (STD), Pelvic in flammatory disease (PID), Vaginiti

    The Comparison of Two Methods of Vaginal Discharge with and without Speculum Examination Diagnosis of Trichomonas Infection

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    Background and Aim: Evaluation for STIs requires speculum examination. It is sometimes uncomfortable and rejected by many patients. Speculum examination often is impractical or not available in remote areas. Recently, it is possible to omit the speculum examination and noninvasively diagnose for Chlamydia and gonorrheal infections from urine sample. This comparison study was conducted by collected vaginal specimens directly without performing a speculum examination for the diagnosis of trichomonas infections.The aim of this study was comparison of two methods of vaginal discharge collection with and without speculum examination for diagnosis of the trichomonas infection.Materials and Methods: We examined 100 patients with vaginal discharge to the gynecology clinic of the Taleghani hospital. Two vaginal swab were collected from vaginal discharge of patients before and during speculum examination for diagnosis of trichomoniasis. Both of vaginal specimens were tested with blinded microscopic. Compared collection methods sensitivities, specificity, positive predictive value, negative predictive value and accuracy of both methods was compared.Results: Sensitivities, specificity, positive predictive value, negative predictive value and accuracy of speculum collection methods were 69%, 99%, 92% ,94% and 93% for trichomoniasis respectively. Sensitivities, specificity, positive predictive value, negative predictive value and accuracy of nonspeculum collection methods were 62.5%, 99%, 91%, 93% and 92% for trichomoniasis respectively. The differences between methods was not statistically significant (P= NS). There was a very good agreement between both methods for diagnosis of trichomoniasis (KAPPA= o.85).Conclusions: We have demonstrated the benefit of nonspeculum vaginal specimens for the diagnosis of trichomoniasis. This technique has applicability for studies involving the epidemiology of vaginal infection as well as for home diagnostic testing ,elder and pregnant women respectively

    Simultaneous Spectrophotometric Determination of Amitriptyline Hydrochloride and Chlordiazepoxide in Pharmaceutical Tablets by Multivariate Calibration Method

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    The multivariate calibration method, partial least square regression (PLS) was applied for the simultaneous spectrophotometry determination of amitriptyline hydrochloride (AMT) and chlordiazepoxide (CHL) in their mixtures. The parameters of chemometric technique were optimized and the proposed method was validated with synthetic samples and applied to analyze these drugs in pharmaceutical products with good accuracy and precision. The results were compared with those given by United State Pharmacopoeia method. The square of the correlation coefficients (R2) for predicted AMT and CHL with the proposed method in a test sample were 0.9951 and 0.9897 respectively. The relative standard deviation for commercial tablets in the proposed method and USP standard method were 0.42 and 2.61%, respectively

    Accuracy of Step Count Estimations in Parkinson's Disease Can Be Predicted Using Ambulatory Monitoring.

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    OBJECTIVES: There are concerns regarding the accuracy of step count in Parkinson's disease (PD) when wearable sensors are used. In this study, it was predicted that providing the normal rhythmicity of walking was maintained, the autocorrelation function used to measure step count would provide relatively low errors in step count. MATERIALS AND METHODS: A total of 21 normal walkers (10 without PD) and 27 abnormal walkers were videoed while wearing a sensor [Parkinson's KinetiGraph (PKG)]. Median step count error rates were observed to be <3% in normal walkers but ≥3% in abnormal walkers. The simultaneous accelerometry data and data from a 6-day PKG were examined and revealed that the 5th percentile of the spectral entropy distribution, among 10-s walking epochs (obtained separately), predicted whether subjects had low error rate on step count with reference to the manual step count from the video recording. Subjects with low error rates had lower Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS III) scores and UPDRS III Q10-14 scores than the high error rate counterparts who also had high freezing of gait scores (i.e., freezing of gait questionnaire). RESULTS: Periods when walking occurred were identified in a 6-day PKG from 190 non-PD subjects aged over 60, and 155 people with PD were examined and the 5th percentile of the spectral entropy distribution, among 10-s walking epochs, was extracted. A total of 84% of controls and 72% of people with PD had low predicted error rates. People with PD with low bradykinesia scores (measured by the PKG) had step counts similar to controls, whereas those with high bradykinesia scores had step counts similar to those with high error rates. On subsequent PKGs, step counts increased when bradykinesia was reduced by treatment and decreased when bradykinesia increased. Among both control and people with PD, low error rates were associated with those who spent considerable time making walks of more than 1-min duration. CONCLUSION: Using a measure of the loss of rhythmicity in walking appears to be a useful method for detecting the likelihood of error in step count. Bradykinesia in subjects with low predicted error in their step count is related to overall step count but when the predicted error is high, the step count should be assessed with caution

    The Level of Islamic Religiosity of the Local Community and Corporate Environmental Responsibility Disclosure: Evidence from Iran

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    The purpose of this paper is to examine the relationship between the Islamic religiosity of the local community and the level of corporate environmental responsibility disclosure (CERD) in Iran, an example of an Islamic country. This paper also examines the moderating role of firm size, family ownership, and state ownership. This study is conducted using a sample of 952 observations across firms listed on the Tehran Stock Exchange. The results indicate that CERD increases with an increase in the level of Islamic religiosity of the province where the firm is located. Also, findings reveal that firm size and family ownership strengthen the aforementioned relationship. However, we provide evidence suggesting that state ownership weakens the positive relationship between the Islamic religious atmosphere and CERD. The results of this research present a new insight suggesting that the Islamic values governing a local community can significantly affect executives’ decisions regarding disclosures, particularly resulting in a decrease in executives’ selfishness and encouraging them to disclose more information about environmental responsibilities
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