42,275 research outputs found

    Multi-rate relaying for performance improvement in IEEE 802.11 WLANs

    Get PDF
    It is well known that the presence of nodes using a low data transmit rate has a disproportionate impact on the performance of an IEEE 802.11 WLAN. ORP is an opportunistic relay protocol that allows nodes to increase their effective transmit rate by replacing a low data rate transmission with a two-hop sequence of shorter range, higher data rate transmissions, using an intermediate node as a relay. ORP differs from existing protocols in discovering relays experimentally, by optimistically making frames available for relaying. Relays identify themselves as suitable relays by forwarding these frames. This approach has several advantages compared with previously proposed relay protocols: Most importantly, ORP does not rely on observations of received signal strength to infer the availability of relay nodes and transmit rates. We present analytic and simulation results showing that ORP improves the throughput by up to 40% in a saturated IEEE 802.11b network

    Existence of a Condorcet winner when voters have other-regarding preferences

    Get PDF
    In standard political economy models, voters are ‘self-interested’ i.e. care only about ‘own’ utility. However, the emerging evidence indicates that voters often have ‘other-regarding preferences’ (ORP), i.e., in deciding among alternative policies voters care about their payoffs relative to others. We extend a widely used general equilibrium framework in political economy to allow for voters with ORP, as in Fehr- Schmidt (1999). In line with the evidence, these preferences allow voters to exhibit ‘envy’ and ‘altruism’, in addition to the standard concern for ‘own utility’. We give sufficient conditions for the existence of a Condorcet winner when voters have ORP. This could open the way for an incorporation of ORP in a variety of political economy models. Furthermore, as a corollary, we give more general conditions for the existence of a Condorcet winner when voters have purely selfish preferences.Redistribution; other regarding preferences; single crossing property

    The use of redox potential to estimate free chlorine in fresh produce washing operations : possibilities and limitations

    No full text
    Maintaining free chlorine (FC) residual at appropriate pH values is a control approach used to prevent pathogen cross-contamination during tomato dump tank handling and fresh-cut produce washing operations. Oxidation reduction potential (ORP) is a rapid measurement of oxidant-based sanitizer strength, and has been used to estimate FC residual. However, factors, in addition to FC and pH, which influence ORP are not fully understood. This study examined the relationship between ORP and FC under chlorine demand (CLD) free conditions and during fresh produce washing. An equation predictive of FC was developed in the form logFC = f(ORP, ORP2, ORP.pH). A good correlation between ORP and logFC was maintained when other variables changed, but the resulting ORP-logFC curve changed (slope, intercept). A decrease in pH or temperature led to an increase in ORP. Using tap water to wash the produce instead of distilled water significantly changed the ORP. For different types of tested produce, i.e., fresh-cut carrot, onion, romaine and iceberg lettuce, and for whole tomatoes, increasing the product-to-water ratio (i.e., increasing the organics transferred into the water) led to a decrease in ORP for a specific FC residual. The choice of acidulant during washing also influenced ORP. Overall, the correlation of ORP with logFC is more reliable at the lower end (5 mg/L FC) than at the higher end (100 mg/L FC) of the FC range used in fresh produce washing. However, since the ORP in fresh produce wash water is affected significantly in multiple ways by the wash water and process conditions, the predicted FC values with ORP under certain fresh-cut produce washing conditions cannot be generalized for other conditions

    OBJECTIVES, PERFORMANCES, RESULTS – VIEWS ON THEIR USE IN THE PUBLIC ORGANIZATIONS FROM ROMANIA

    Get PDF
    The pre sent paper focuses on the management associated with relatively common concepts: objective, result and performance (ORP). The study is important because in the Romania of the year 2011, a “state reform” is being planned, which will substantiate into the reorganization of public institutions, as the improvement of their activity is set forth by utilizing the set of tools associated with the aforementioned concepts. The study represents an analysis related to the use of the set of management tools associated with the aforementioned concepts within the Romanian public organizations. The study is concerned with a qualitative estimation involving the translation of the existing theory into the practice of the present moment. The review of the specialized literature is aimed at selecting the most common theoretical milestones, in order to increase the probability to retrieve them from the practice of the organizations. The works of Drucker represent the first theoretical system of reference. The way the ORP concepts have been utilized within the American organizations generate the guiding elements of the present study. The research presents a longitudinal segmentation, the frontier between the two parts being the present moment. The current state of facts is studied by means of an inductive approach. The hypothesis related to the ORP management in the near future is actually built on the grounds provided by the estimation of this state of facts. Its deductive approach starts from evaluating the pragmatic premises, involving the support of the process that will utilize the ORP in the near future, according to the theoretical percepts. The analysis is qualitative in nature. The identification of the cases that represented “the exception” was taken into account. The analysis focused on public institutions considered a priori as more transparent: the university, the hospital and the town hall. Even if in the case of the university there are regulations that facilitate the strategic planning, the utilization of objectives according to the MBO precepts is absent. The same situation is to be found in the case of hospitals and town halls. The use of primary and secondary information sources prove that the ORP has not been utilized. It was ascertained that the premises for utilizing the ORP are the same for the near future, a fact that implies the same results. The main implication is associated with the “myth or reality?” question. The result has a demystifying impact, showing that a reliable estimation on the ORP basis related to the activities of or people working in these organizations cannot be developed nowadays - in 2011. The present study aims at a realistic analysis related to the discrepancy between words and facts within the management of the Romanian public organizations. The fact that the aforementioned organizations represent the object of the “management of shallow labels content” is signaled and demonstrated.objectives, MBO, results, performance, public organization

    Unsuitability of the Oxidation-Reduction Potential Measurement for the Quantification of Fecal Redox Status in Inflammatory Bowel Disease

    Get PDF
    Oxidative stress is a key pathophysiological process associated with the development and progression of inflammatory bowel disease (IBD). Biomarkers for oxidative stress, however, are scarce, as are diagnostic tools that can interrogate an individual’s gut redox status. This proof- of-concept study aimed to evaluate the potential utility of an oxidation-reduction potential (ORP) measurement probe, to quantify redox status in the feces of both patients with IBD and healthy controls. Previous studies using this ORP measurement probe demonstrated promising data when comparing ORP from severely malnourished individuals with that of healthy controls. To date, ORP analyses have not been performed in the context of IBD. We hypothesized that measuring the ORP of fecal water in patients with IBD might have diagnostic value. The current study, however, did not show significant differences in ORP measurement values between patients with IBD (median [IQR] 46.5 [33.0–61.2] mV) and healthy controls (25 [8.0–52.0] mV; p = 0.221). Additionally, ORP measurements were highly unstable and rapidly fluctuated throughout time, with ORP values varying from +24 to +303 mV. Due to potential biological processes and limitations of the measuring equipment, this study was unable to reliably measure ORP. As a result, our findings indicate that ORP quantification may not be a suitable method for assessing fecal redox status and, therefore, does not currently support further exploration as a diagnostic or monitoring tool

    Optimization of a Diagnostic Platform for Oxidation-Reduction Potential (ORP) Measurement in Human Plasma and Exploration of ORP after Trauma

    Get PDF
    Oxidation-reduction potential (ORP) measurement has demonstrated oxidative stress in patients with severe illness/injury. A new ORP diagnostic platform using disposable sensors (Supplemental Figure 1) has been validated by comparison to mass spectrometry, but the response of ORP to experimental positive and negative control conditions has not been determined. Furthermore, optimal methods of sample handling for ORP measurement have not been studied. We sought to optimize ORP measurement in human plasma, under controlled conditions. We hypothesized that freeze-thawing of the sample, storage of the sample for up to one month, and the method of sample anticoagulation would influence ORP levels. Furthermore, we hypothesized that ORP can detect incremental experimental changes that either increase or decrease redox state. Finally, we hypothesized that trauma injuries cause increased levels of reactive oxygen species (ROS) in the circulating bloodstream, and therefore would reflect higher ORP signals in plasma measurements in both human and mouse subjects. We enrolled healthy human volunteers in a prospective observational study and measured ORP in plasma prepared with heparin or citrate anticoagulants directly after blood draw and up to 28 days later. Additionally, we evaluated the platform’s ability to detect an exogenous increase and decrease in ORP by performing both positive and negative control titrations using six different concentrations of hydrogen peroxide (H2O2) and two different concentrations of ascorbic acid respectively. Lastly, we compared human trauma plasma samples in an uncontrolled emergency room setting with healthy human plasma and then mimicked this experiment in a more controlled mouse model experiment. We found that fresh plasma better retains the ORP signal as compared to freeze-thaw samples measured on subsequent days. We also found that the platform can detect exogenous, concentration-dependent oxidations with H2O2 and reductions with ascorbic acid. Furthermore, plasma prepared with heparin is more sensitive than using citrate anticoagulant when measuring ORP. Also, human trauma patients’ plasma (of varying degrees of trauma) samples were characterized by significantly higher ORP signals than healthy controls when measured in heparin anticoagulant, whereas mouse ORP signals did not change following a controlled, moderate traumatic brain injury. These data indicate that the diagnostic platform is capable of detecting exogenous increases and decreases in ORP signal from plasma samples with validity and is sensitive to different concentrations of positive and negative controls. We also show that plasma should be collected and centrifuged in heparin anticoagulant tubes and can be analyzed fresh or frozen for optimal results

    POLA PERUBAHAN K-VALUE dan ORP IKAN CAKALANG (Katsuwonus pelamis) PADA PENYIMPANAN SUHU RENDAH ( +11 0C )

    Get PDF
    ABSTRAK Kesegaran ikan merupakan hal yang sangat penting dalam menentukan keseluruhan mutu daripada suatu produk perikanan. K-value dan ORP merupakan salah satu metode penentu kesegaran secara kimia dan fisiko kimia. Kecepatan ikan membusuk terutama dipengaruhi suhu. Penelitian ini bertujuan untuk mengetahui perubahan K-value dan ORP serta pola perubahannya pada penyimpanan suhu rendah (+ 110C) menggunakan refrigerator dari Ikan Cakalang. Penelitian dilaksanakan di Laboratorium Teknologi Hasil Perikanan FPIK Universitas Diponegoro Semarang dan Pusat Antar Universitas Pangan dan Gizi UGM Yogyakarta. Materi yang digunakan dalam penelitian adalah Ikan Cakalang segar. Metode penelitian adalah eksperimental laboratorisyang bersifat deskriptif eksploratif. Penentuan K-value menggunakan metode Ion Exchange Chromatografi yang dibaca dengan spektrofotometri. Oksidasi Reduksi Potensial (ORP) diukur berdasar metode Okouchi et al ( 1965 ) dengan menggunakan elektrometer (pH meter TPX 90I) dimana memiliki dua elektrode yaitu elektroda platinum untuk mengukur ORP dan elektroda glass untuk mengukur pH. Hasil penelitian menunjukkan K-value awal pada penyimpanan suhu rendah (+ 110C) Ikan Cakalang 21.90 % . K-value Ikan Cakalang turun pada hari ke-10 yaitu dari 51,58 % menjadi 43,73 %. Pada penyimpanan suhu rendah nilai ORP Ikan Cakalang naik dari kondisi awal yaitu 0.22 Volt menjadi 0,25 dan 0,26 volt pada penyimpanan hari ke-2 dan ke-3 kemudian turun menjadi 0,24 hingga – 0,23 volt pada hari ke-10. Nilai ORP negatif dicapai Ikan Cakalang pada hari ke-8. Nilai pH Ikan Cakalang di bawah netral (7) pada semua pengukuran. Pada penyimpanan suhu rendah Ikan Cakalang mempunyai pH awal 5,8 dan pH akhir 6,42. Pola Hubungan K-value dan ORP pada penyimpanan suhu rendah ORP naik kemudian turun bersamaan dengan kenaikan K-value. Kata kunci : Suhu penyimpanan, K-value, ORP, Ikan Cakalang (Katsuwonus pelamis

    Effect of salt concentration on the properties of electrolyzed reducing water (ERW) and electrolyzed oxidizing water (EOW): an empirical correlation study

    Get PDF
    This research aimed to examine the effect of NaCl concentration on the pH and Oxidation Reduction Potential (ORP) values of both EOW and ERW products. The experiment was conducted using distilled water. The electrolysis apparatus consisted of anode and cathode chambers. The chambers were connected by a tube filled with a cotton (or a fabric). Both electrodes (anode and cathode) were made of titanium and formed as a spiral. Electrolysis was performed for 780 minutes, and the pH and ORP values of both EOW and ERW were measured every time. Sodium chloride concentration was varied for 0, 100, and 200 ppm. Experimental results revealed that the higher the NaCl concentration, the higher ERW’s pH rise and the lower the EOW’s pH. Similar results were found for ORP. ERW’s ORP was lowered while EOW’s ORP rose with the increase in NaCl concentration. This study could also generate a mathematical model that correlates pH and time during the electrolysis process. The model was developed by connecting with a simple polynomial. A similar approach was used to develop the model that correlates pH and ORP value

    Oxidation–reduction potential and sperm DNA fragmentation, and their associations with sperm morphological anomalies amongst fertile and infertile men

    Get PDF
    Objective: To assess seminal oxidation–reduction potential (ORP) and sperm DNA fragmentation (SDF) in male infertility and their relationships with sperm morphology in fertile and infertile men. Patients and methods: Prospective case-control study comparing the findings of infertile men (n = 1168) to those of men with confirmed fertility (n = 100) regarding demographics and semen characteristics (conventional and advanced semen tests). Spearman rank correlation assessed the correlation between ORP, SDF, and different morphological indices. Means of ORP and SDF were assessed in variable levels of normal sperm morphology amongst all participants. Results: Infertile patients had a significantly lower mean sperm count (32.7 vs 58.7 × 10 6 sperm/mL), total motility (50.1% vs 60.4%), and normal morphology (5.7% vs 9.9%). Conversely, infertile patients had significantly higher mean head defects (54% vs 48%), and higher ORP and SDF values than fertile controls. ORP and SDF showed significant positive correlations and significant negative correlations with sperm head defects and normal morphology in infertile patients, respectively. ORP and SDF were significantly inversely associated with the level of normal sperm morphology. Using receiver operating characteristic curve analysis, ORP and SDF threshold values of 1.73 mV/10 6 sperm/mL and 25.5%, respectively, were associated with 76% and 56% sensitivity and 72% and 72.2% specificity, respectively, in differentiating <4% from ≄4% normal morphology. Conclusion: A direct inverse relationship exists between seminal ORP and SDF with various levels of normal sperm morphology. Using ORP and SDF measures in conjunction with standard semen morphology analysis could validate the result of the fertility status of patients. © 2017 Arab Association of UrologyScopu
    • 

    corecore