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Showing papers by "Ben-Gurion University of the Negev published in 2000"


Journal ArticleDOI
TL;DR: In this study, consumers recognized differences in size and reputation among Internet stores, and those differences influenced their assessments of store trustworthiness and their perception of risk, as well as their willingness to patronize the store.
Abstract: The study reported here raises some questions about the conventional wisdom that the Internet creates a “level playing field” for large and small retailers and for retailers with and without an established reputation. In our study, consumers recognized differences in size and reputation among Internet stores, and those differences influenced their assessments of store trustworthiness and their perception of risk, as well as their willingness to patronize the store. After describing our research methods and results, we draw some implications for Internet merchants.

2,751 citations


Journal ArticleDOI
TL;DR: The results resemble those found by social psychologists regarding the effect of physical attractiveness on the valuation of other personality attributes and stress the importance of studying the aesthetic aspect of human–computer interaction (HCI) design and its relationships to other design dimensions.

1,260 citations


Book
01 Jan 2000
TL;DR: A formal impossibility proof shows that, in order to ensure the correct behavior of the system, less than one-third of the processors may be of the Byzantine type; that is, to design the system as if there were no (yesterday) past history—a system that can be started in any possible state of its state space.
Abstract: AULT tolerance and reliability are important issues for flight vehicles such as aircraft, space-shuttles, and satellites. A self-stabilizing system recovers automatically following disturbances that force the system to an arbitrary state. The self-stabilization concept is an essential property of any autonomous control/computing system. Important branches of distributed computing theory were initiated because of the need for fault-tolerance of aircraft computing devices. The Byzantine fault model, for example, was a creation of the NASA SIFT project of more than a couple of decades ago. The Byzantine fault model is an elegant abstraction of faults where it is assumed that faulty parts behave as adversaries. The idea is to use redundancy—for instance, in the number of processors—in order to overcome the behavior of faulty processors. This line of thinking fits the common practice in engineering in which the design of critical parts is done independently by several design teams to make sure that there is no mistake in the calculations. Analogously, in the Byzantine fault model, some processors are simultaneously computing the same calculations for implementing a robust flight controller; thus the flight controller can function well in spite of the faulty behavior of several of the processors. Faulty behavior cannot be anticipated, the most severe behavior is therefore assumed—one that is reminiscent of the behavior of an adversary in the Byzantine court, in which backstabbing was common. A formal impossibility proof shows that, in order to ensure the correct behavior of the system, less than one-third of the processors may be of the Byzantine type. The task examined is the agreement, or consensus, for which processors need to decide on the same output, which is the input of one of the processors. The decision can be viewed as choosing the common result among the results of the design teams in the engineering example. The intuition behind the impossibility result is as follows: assume you have met two persons, Alice and Bob, one of which is honest while the other is not. You may try to decide what to do by speaking with each of them. Because you do not know which of the two is honest, you have to find this out. You may try a direct question to Alice asking who among them is not honest; Alice will answer Bob, and Bob, if asked, will obviously answer Alice. Each of them may also describe the conversations he/she had with the other, knowing that no one listened to the communication between them. This symmetry in the weights of the answers of Alice and Bob make it impossible to decide. It is possible to formally prove that agreement can be achieved if, and only if, less than one-third of the processors are Byzantine (e.g. Ref. 7). Systems that tolerate Byzantine faults are designed for flight devices, which need to be extremely robust. In such a device, the assumptions made for reaching agreement can be violated: Is it reasonable to assume that, during any period of the execution, less than one-third of the processors are faulty? What happens if, for a short period, more than a third are faulty, or perhaps experience a weaker fault than a Byzantine fault (say, caused by a transient electric spark)? What happens if messages sent by non-faulty processors are lost in one instant of time? Seven years prior to the introduction of the Byzantine fault model, Edsger W. Dijkstra suggested an important fundamental fault tolerance property called self-stabilization; 3 that is, to design the system as if there were no (yesterday) past history—a system that can be started in any possible state of its state space. It would therefore not be assumed that consistency was maintained from the fixed initial state by always executing steps according to the program of the processors. Self-stabilizing systems thus overcome transient faults. Temporary violations of the assumptions made by the algorithm designer can be viewed as leaving the system in an arbitrary initial state from which the system resumes. Self-stabilizing systems work correctly when started in any initial system state. Thus, even if the system loses its consistency due to an unexpected temporary violation of the assumptions made, it converges to legal behavior once the assumptions start to hold again. Self-stabilization is a strong fault tolerance property for systems; it ensures automatic recovery once faults stop occurring. A self-stabilizing system is designed to start in any possible state where its components—e.g., processors, processes, communication links, communication buffers—are in an arbitrary state; i.e., arbitrary variable values,

1,163 citations


Journal ArticleDOI
TL;DR: Participants switched between two randomly ordered, two-choice reaction-time (RT) tasks, where an instructional cue preceded the target stimulus and indicated which task to execute and switching cost was sharply reduced.

581 citations


Journal ArticleDOI
TL;DR: After implantation into the infarcted myocardium, the biografts stimulated intense neovascularization and attenuated LV dilatation and failure in experimental rats compared with controls, suggesting alginate scaffolds provide a conducive environment to facilitate the 3D culturing of cardiac cells.
Abstract: Background—The myocardium is unable to regenerate because cardiomyocytes cannot replicate after injury. The heart is therefore an attractive target for tissue engineering to replace infarcted myocardium and enhance cardiac function. We tested the feasibility of bioengineering cardiac tissue within novel 3-dimensional (3D) scaffolds. Methods and Results—We isolated and grew fetal cardiac cells within 3D porous alginate scaffolds. The cell constructs were cultured for 4 days to evaluate viability and morphology before implantation. Light microscopy revealed that within 2 to 3 days in culture, the dissociated cardiac cells form distinctive, multicellular contracting aggregates within the scaffold pores. Seven days after myocardial infarction, rats were randomized to biograft implantation (n=6) or sham-operation (n=6) into the myocardial scar. Echocardiography study was performed before and 65±5 days after implantation to assess left ventricular (LV) remodeling and function. Hearts were harvested 9 weeks afte...

580 citations


Journal ArticleDOI
TL;DR: The results suggest that astaxanthin synthesis proceeds via cantaxanth in Haematococcus and that this exceptional stress response is mediated by reactive oxygen species (ROS) through a mechanism which is not yet understood.
Abstract: The unicellular green alga Haematococcus pluvialis Flotow has recently aroused considerable interest due to its capacity to amass large amounts of the ketocarotenoid astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4′-dione), widely used commercially to color flesh of salmon. Astaxanthin accumulation in Haematococcus is induced by a variety of environmental stresses which limit cell growth in the presence of light. This is accompanied by a remarkable morphological and biochemical ‘transformation’ from green motile cells into inert red cysts. In recent years we have studied this transformation process from several aspects: defining conditions governing pigment accumulation, working out the biosynthetic pathway of astaxanthin accumulation and questioning the possible function of this secondary ketocarotenoid in protecting Haematococcus cells against oxidative damage. Our results suggest that astaxanthin synthesis proceeds via cantaxanthin and that this exceptional stress response is mediated by reactive oxygen species (ROS) through a mechanism which is not yet understood. The results do not support in vivo chemical quenching of ROS by the pigment, although in vitro it was shown to quench radicals very efficiently. The finding that most of the pigment produced is esterified and deposited in lipid globules outside the chloroplast further supports this assumption. We have suggested that astaxanthin is the by-product of a defense mechanism rather than the defending substance itself, although at this stage one cannot rule out other protective mechanisms. Further work is required for complete understanding of this transformation process. It is suggested that Haematococcus may serve as a simple model system to study response to oxidative stress and mechanisms evolved to cope with this harmful situation.

532 citations


Journal ArticleDOI
TL;DR: Results of numerical calculation for nonlinear steady state convection, developing from the respective instability, are reported along with those for a slightly wavy membrane and also the results of recent experiments with modified membranes.
Abstract: The paper is concerned with convection at an ion exchange electrodialysis membrane induced by nonequilibrium electro-osmosis in the course of concentration polarization under the passage of electric current through the membrane. Derivation of nonequilibrium electro-osmotic slip condition is recapitulated along with the linear stability analysis of quiescent electrodiffusion through a flat ion exchange membrane. Results of numerical calculation for nonlinear steady state convection, developing from the respective instability, are reported along with those for a slightly wavy membrane. Besides these results, we report those of time dependent calculations for periodic and chaotic oscillations, resulting from instability of the respective steady state flows, and also the results of recent experiments with modified membranes. These latter rule in favor of electro-osmotic versus bulk electroconvective origin of overlimiting conductance through ion exchange membranes.

498 citations


Journal ArticleDOI
TL;DR: The results suggest that NR2E3 has a role in determining photoreceptor phenotype during human retinogenesis, and may be due to abnormal cone cell fate determination during retinal development.
Abstract: Hereditary human retinal degenerative diseases usually affect the mature photoreceptor topography by reducing the number of cells through apoptosis, resulting in loss of visual function1. Only one inherited retinal disease, the enhanced S-cone syndrome (ESCS), manifests a gain in function of photoreceptors. ESCS is an autosomal recessive retinopathy in which patients have an increased sensitivity to blue light; perception of blue light is mediated by what is normally the least populous cone photoreceptor subtype, the S (short wavelength, blue) cones2,3,4,5,6,7,8. People with ESCS also suffer visual loss, with night blindness occurring from early in life, varying degrees of L (long, red)- and M (middle, green)-cone vision, and retinal degeneration. The altered ratio of S- to L/M-cone photoreceptor sensitivity in ESCS may be due to abnormal cone cell fate determination during retinal development7. In 94% of a cohort of ESCS probands we found mutations in NR2E3 (also known as PNR), which encodes a retinal nuclear receptor recently discovered to be a ligand-dependent transcription factor9. Expression of NR2E3 was limited to the outer nuclear layer of the human retina. Our results suggest that NR2E3 has a role in determining photoreceptor phenotype during human retinogenesis.

461 citations


Journal ArticleDOI
TL;DR: A quantitative model is suggested that participants dynamically control response accuracy by selective attention, in the particular paradigm being used, by controlling stimulus representation, and are less efficient in dynamically controlling response representation.
Abstract: This article describes a quantitative model, which suggests what the underlying mechanisms of cognitive control in a particular task-switching paradigm are, with relevance to task-switching performance in general. It is suggested that participants dynamically control response accuracy by selective attention, in the particular paradigm being used, by controlling stimulus representation. They are less efficient in dynamically controlling response representation. The model fits reasonably well the pattern of reaction time results concerning task switching, congruency, cue-target interval and response-repetition in a mixed task condition, as well as the differences between mixed task and pure task conditions.

416 citations


Journal ArticleDOI
TL;DR: Several culturally specific practical considerations should inform social work interventions with ethnic Arab peoples in Arab countries or in Western nations, taking into account gender relations, individuals' places in their families and communities, patterns of mental health services use, and the client's level of acculturation.
Abstract: Several culturally specific practical considerations should inform social work interventions with ethnic Arab peoples in Arab countries or in Western nations. These include taking into account gender relations, individuals' places in their families and communities, patterns of mental health services use, and, for practice in Western nations, the client's level of acculturation. Such aspects provide the basis for specific guidelines in working with ethnic Arab mental health clients. These include an emphasis on short-term, directive treatment; communication patterns that are passive and informal; patients' understanding of external loci of control and their use of ethnospecific idioms of distress; and, where appropriate, the integration of modern and traditional healing systems.

415 citations


Journal ArticleDOI
01 Sep 2000
TL;DR: This work investigates the suitability of a fully automated, simple, objective, quantitative and reproducible method that can be used in the automatic assessment of models in the upcoming CAFASP2 experiment and concludes that MaxSub is a suitable method for the automatic evaluation of models.
Abstract: Motivation: Evaluating the accuracy of predicted models is critical for assessing structure prediction methods. Because this problem is not trivial, a large number of different assessment measures have been proposed by various authors, and it has already become an active subfield of research (Moultet al., 1999). The CASP (Moult et al., 1997, 1999) and CAFASP (Fischeret al., 1999) prediction experiments have demonstrated that it has been difficult to choose one single, ‘best’ method to be used in the evaluation. Consequently, the CASP3 evaluation was carried out using an extensive set of especially developed numerical measures, coupled with humanexpert intervention. As part of our efforts towards a higher level of automation in the structure prediction field, here we investigate the suitability of a fully automated, simple, objective, quantitative and reproducible method that can be used in the automatic assessment of models in the upcoming CAFASP2 experiment. Such a method should (a) produce one single number that measures the quality of a predicted model and (b) perform similarly to humanexpert evaluations. Results: MaxSub is a new and independently developed method that further builds and extends some of the evaluation methods introduced at CASP3. MaxSub aims at identifying the largest subset of Cα atoms of a model that superimpose ‘well’ over the experimental structure, and produces a single normalized score that represents the quality of the model. Because there exists no evaluation method for assessment measures of predicted models, it is not easy to evaluate how good our new measure is. Even though an exact comparison of MaxSub and the CASP3 assessment is not straightforward, here we use a test

Journal ArticleDOI
TL;DR: The correlation between the proposed WDD measure and the MOS test measure (MOS/sub error/) was found superior to the correlation betweenThe popular PRD measure andThe MOS/ sub error/.
Abstract: In this paper, a new distortion measure for electrocardiogram (ECG) signal compression, called weighted diagnostic distortion (WDD) is introduced. The WDD measure is designed for comparing the distortion between original ECG signal and reconstructed ECG signal (after compression). The WDD is based on PQRST complex diagnostic features (such as P wave duration, QT interval, T shape, ST elevation) of the original ECG signal and the reconstructed one. Unlike other conventional distortion measures [e.g. percentage root mean square (rms) difference, or PRD], the WDD contains direct diagnostic information and thus is more meaningful and useful. Four compression algorithms were implemented (AZTEC, SAPA2, LTP, ASEC) in order to evaluate the WDD. A mean opinion score (MOS) test was applied to test the quality of the reconstructed signals and to compare the quality measure (MOS/sub error/) with the proposed WDD measure and the popular PRD measure. The evaluators in the WIGS test were three independent expert cardiologists, who studied the reconstructed ECG signals in a blind and a semiblind tests. The correlation between the proposed WDD measure and the MOS test measure (MOS/sub error/) was found superior to the correlation between the popular PRD measure and the MOS/sub error/.

Journal ArticleDOI
TL;DR: HRV analysis demonstrates significant differences in autonomic regulation of PTSD and PD patients compared to each other and to control subjects, and may augment biochemical studies of peripheral measures in these disorders.
Abstract: Power spectral analysis (PSA) of heart rate variability (HRV) offers reliable assessment of cardiovascular autonomic responses, providing a 'window' onto the interaction of peripheral sympathetic and parasympathetic tone Alterations in HRV are associated with various physiological and pathophysiological processes, and may contribute to morbidity and mortality Previous studies of posttraumatic stress disorder (PTSD) found lower resting HRV in patients compared to controls, suggesting increased sympathetic and decreased parasympathetic tone This article describes the analysis of HRV at rest and after psychological stress in panic disorder (PD) patients, in an enlarged sample of PTSD patients, and in healthy control subjects Standardized heart rate (HR) analysis was carried out in 14 PTSD patients, 11 PD patients and 25 matched controls ECG recordings were made while subjects were resting ('rest 1'), while recalling the trauma implicated in PTSD, or the circumstances of a severe panic attack, as appropriate ('recall'), and again while resting ('rest 2') Controls were asked to recall a stressful life event during recall While both patient groups had elevated HR and low frequency (LF) components of HRV at baseline (suggesting increased sympathetic activity), PTSD patients, unlike PD patients and controls, failed to respond to the recall stress with increases in HR and LF HRV analysis demonstrates significant differences in autonomic regulation of PTSD and PD patients compared to each other and to control subjects HRV analysis may augment biochemical studies of peripheral measures in these disorders

Journal ArticleDOI
TL;DR: The studies show that alginate sponges can provide a conducive environment to facilitate the performance of cultured hepatocytes by enhancing their aggregation.
Abstract: A potential approach to facilitate the performance of implanted hepatocytes is to enable their aggregation and re-expression of their differentiated function prior to implantation. Here we examined the behavior of freshly isolated rat adult hepatocytes seeded within a novel three-dimensional (3-D) scaffold based on alginate. The attractive features of this scaffold include a highly porous structure (sponge-like) with interconnecting pores, and pore sizes with diameters of 100-150 microm. Due to their hydrophilic nature, seeding hepatocytes onto the alginate sponges was efficient. DNA measurements showed that the total cell number within the sponges did not change over 2 weeks, indicating that hepatocytes do not proliferate under these culture conditions. Nearly all seeded cells maintained viability, according to the MTT assay. Within 24 h post-seeding, small clusters of viable cells, were seen scattered within the sponge. More than 90% of the seeded cells participated in the aggregation; the high efficiency is attributed to the non-adherent nature of alginate. The spheroids had smooth boundaries and by day 4 in culture reached an average diameter of 100 microm, which is at the same magnitude of the sponge pore size. The cells appeared to synthesize fibronectin which was deposited on the spheroids. No laminin or collagen type IV were detected in the deposit. The 3-D arrangement of hepatocytes within the alginate sponges promoted their functional expression; within a week the cells secreted the maximal albumin secretion rate of 60 microg albumin/10(6) cells/day. Urea secretion rate did not depend on cell aggregation and was similar to that obtained when hepatocytes were cultured on collagen type I coated dishes (100 microg/10(6) cells/day). Our studies show that alginate sponges can provide a conducive environment to facilitate the performance of cultured hepatocytes by enhancing their aggregation.

Journal ArticleDOI
TL;DR: In this article, a modified polyethersulfone (PES) ultrafiltration membrane was characterized by FTIR-ATR spectroscopy to detect chemical changes during modification.

Journal ArticleDOI
TL;DR: The basal autonomic state of patients with FM is characterized by increased sympathetic and decreased parasympathetic tones, which may have implications regarding the symptomatology, physical and psychological aspects of health status.

Journal ArticleDOI
TL;DR: In this article, the authors raise a number of broad questions about the communicative paradigm and claim for its theoretical dominance and point out alternative analytical positions that focus on issues of power, of the state, and of political economy.
Abstract: During the last decade or so, many planning theorists have taken a so-called communicative turn, to the point where somiie have declared the emergence of a dominant new paradigm supported by increasing consensus among theorists. We wish to raise a number of broad questions about the communicative paradigm and claims for its theoretical dominance. We point to alternative analytical positions that focus on issues of power, of the state, and of political economy, in ways that are often underplayed in the communicative literature and that demonstrate a healthy diversity in the field. We offer six critical propositions about communicative planning theory as a contribution to the ongoing debates, in theory and practice, about the conitested nature of planning, its practices and effects.

Journal ArticleDOI
TL;DR: These results help to define specific personality features reproducibly associated with 5-HTTLPR genotype, enhancing the attractiveness of the five-factor personality model in genetic research on complex behavioral dimensions.
Abstract: The serotonin transporter (5-HTT) regulates serotonergic neurotransmission and is thought to influence emotion. A 5-HTT-linked polymorphic region (5-HTTLPR) has two common variants, short (s) and long (l). We previously found population and within-family associations between the lower-expressing s allele and neuroticism, a trait related to anxiety, hostility, and depression, on a standard measure (the NEO Personality Inventory, Revised [NEO-PI-R]) in a primarily male population (n=505), and that the s allele was dominant. We investigated this association in a new sample (n=397, 84% female, primarily sib-pairs). The results robustly replicated the 5-HTTLPR neuroticism association, and the dominance of the s allele. Combined data from the two studies (n=902) showed a highly significant association between the s allele and higher NEO Neuroticism both across individuals and within families. Association between genotype and a related measure, Anxiety on the 16PF inventory, was replicated in the new population and within families in the combined sample. Association to another trait, estimated TPQ Harm Avoidance, was not replicated in the new sample but found only within the combined sibship group. Another association found in our original study, between the s allele and lower scores on NEO-PI-R Agreeableness, was also replicated and was more robust in the current and the combined samples. Associations between the functional 5-HTTLPR polymorphism were similar in women and men. These results help to define specific personality features reproducibly associated with 5-HTTLPR genotype. Such associations were strongest for traits defined by the NEO, enhancing the attractiveness of the five-factor personality model in genetic research on complex behavioral dimensions. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:202–216, 2000. Published 2000 Wiley-Liss, Inc.

Journal ArticleDOI
TL;DR: Data suggest that the inhibitory effects of lycopene on MCF7 cell growth are not due to the toxicity of the carotenoid but, rather, to interference in IGF-I receptor signaling and cell cycle progression.
Abstract: Recent studies have shown that high insulin-like growth factor I (IGF-I) blood level is a risk factor in breast and prostate cancer. The aim of this study was to determine whether the mitogenic activity of IGF-I in mammary cancer cells can be reduced by the dietary carotenoid lycopene. The anticancer activity of lycopene, the major tomato carotenoid, has been suggested by in vitro, in vivo, and epidemiological studies. Growth stimulation of MCF7 mammary cancer cells by IGF-I was markedly reduced by physiological concentrations of lycopene. The inhibitory effects of lycopene on MCF7 cell growth were not accompanied by apoptotic or necrotic cell death, as determined by annexin V binding to plasma membrane and propidium iodide staining of nuclei in unfixed cells. Lycopene treatment markedly reduced the IGF-I stimulation of tyrosine phosphorylation of insulin receptor substrate 1 and binding capacity of the AP-1 transcription complex. These effects were not associated with changes in the number or affinity of IGF-I receptors, but with an increase in membrane-associated IGF-binding proteins, which were previously shown in different cancer cells to negatively regulate IGF-I receptor activation. The inhibitory effect of lycopene on IGF signaling was associated with suppression of IGF-stimulated cell cycle progression of serum-starved, synchronized cells. Moreover, in cells synchronized by mimosine treatment, lycopene delayed cell cycle progression after release from the mimosine block. Collectively, the above data suggest that the inhibitory effects of lycopene on MCF7 cell growth are not due to the toxicity of the carotenoid but, rather, to interference in IGF-I receptor signaling and cell cycle progression.

Journal ArticleDOI
TL;DR: It is concluded that serum IL- 6 is increased in obese patients, and the highest IL-6 levels were found in the patients with OHS.
Abstract: Objective: Obese patients demonstrate a variety of biochemical, metabolic, and pulmonary abnormalities. Inflammatory mediators such as tumor necrosis factor-α and interleukin-6 (IL-6) may have a direct effect on glucose and lipid metabolism. Hypoxemia in itself induces release of IL-6. The aim of this study was to examine the relationship between IL-6 levels in healthy volunteers (control group) and three different groups of obese patients: patients without obstructive sleep apnea syndrome (OSAS), patients with OSAS, and patients with obesity hypoventilation syndrome (OHS) (daytime baseline oxygen saturation of <93%). Research Methods and Procedures: We measured serum IL-6 levels in 25 obese patients (body mass index of >35 kg/m2) and 12 healthy women. Results: The results demonstrate statistically significant differences in serum IL-6 levels between the control group (1.28 ± 0.85 pg/mL) and obese patients without OSAS (7.69 ± 5.06 pg/mL, p < 0.05) and with OSAS (5.58 ± 0.37 pg/mL, p < 0.0005). In the patients with OHS, IL-6 concentrations were highest (43.13 ± 24.27 pg/mL). Discussion: We conclude that serum IL-6 is increased in obese patients. The highest IL-6 levels were found in the patients with OHS.

Journal ArticleDOI
TL;DR: ALCAR is reported in double-blind controlled studies to have beneficial effects in major depressive disorders and Alzheimer's disease (AD), both of which are highly prevalent in the geriatric population.
Abstract: Acetyl-L-carnitine (ALCAR) contains carnitine and acetyl moieties, both of which have neurobiological properties. Carnitine is important in the beta-oxidation of fatty acids and the acetyl moiety can be used to maintain acetyl-CoA levels. Other reported neurobiological effects of ALCAR include modulation of: (1) brain energy and phospholipid metabolism; (2) cellular macromolecules, including neurotrophic factors and neurohormones; (3) synaptic morphology; and (4) synaptic transmission of multiple neurotransmitters. Potential molecular mechanisms of ALCAR activity include: (1) acetylation of -NH2 and -OH functional groups in amino acids and N terminal amino acids in peptides and proteins resulting in modification of their structure, dynamics, function and turnover; and (2) acting as a molecular chaperone to larger molecules resulting in a change in the structure, molecular dynamics, and function of the larger molecule. ALCAR is reported in double-blind controlled studies to have beneficial effects in major depressive disorders and Alzheimer's disease (AD), both of which are highly prevalent in the geriatric population.

Journal ArticleDOI
TL;DR: AHP/DEA ranking does not replace the DEA classification model, rather it furthers the analysis by providing full ranking in the DEA context for all units, efficient and inefficient.

Journal ArticleDOI
TL;DR: The FIMP proved very successful in supporting continuous cultures of the tested species of photoautotrophs, addressing the major criteria involved in design optimization of photobioreactors, and resulting in record volumetric and areal output rates of Monodus subterraneus, Anabana siamensis, and Spirulina platensis.
Abstract: A flat inclined modular photobioreactor (FIMP) for mass cultivation of photoautotrophic microorganisms is described. It consists of flat glass reactors connected in cascade facing the sun with the proper tilt angles to assure maximal exposure to direct beam radiation. The optimal cell density in reference to the length of the reactor light path was evaluated, and the effect of the tilt angle on utilization of both direct beam as well as diffuse sunlight was quantitatively assessed. The mixing mode and extent were also optimized in reference to productivity of biomass. The FIMP proved very successful in supporting continuous cultures of the tested species of photoautotrophs, addressing the major criteria involved in design optimization of photobioreactors: Made of fully transparent glass, inclined toward the sun and endowed with a high surface-to-volume ratio, it combines an optimal light path with a vigorous agitation system. The maximal exposure to the culture to solar irradiance as well as the substantial control of temperature facilitate, under these conditions, a particularly high, extremely light-limited optimal cell density. The integrated effects of these growth conditions resulted in record volumetric and areal output rates of Monodus subterraneus, Anabana siamensis, and Spirulina platensis. (c) 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this paper, the authors present a conceptual infrastructure for the reinvigoration of the study of vocational exploration, with a particular emphasis on the means by which individuals can internalize exploratory attitudes and activities.

Journal ArticleDOI
TL;DR: The results of a study conducted among 388 working tourists in Israel demonstrated that the higher the intensity of the social relationship between hosts and working tourists, the more favorable were the tourists' feelings towards their hosts, and the more positive was the change in attitudes towards hosts and the destination as discussed by the authors.

Journal ArticleDOI
TL;DR: Here, it is sought to determine whether such ultrasound facilitates the outward transport of analytes present in the interstitial fluid, thereby allowing noninvasive extraction of clinically useful analytes 12.
Abstract: 1, including implantable sensors 2‐4 , minimally invasive skin microporation approaches involving laser or miniaturized lancets 5 and noninvasive technologies such as near-infrared spectroscopy 5 , transdermal permeation enhancers 6 or reverse iontophoresis 7,8 . However, none are used in routine clinical practice 5 . One of the fundamental problems in noninvasive transdermal diagnostics is obtaining sufficient quantities of analyte for detection. Ultrasound, particularly at low frequencies, enhances transdermal delivery of drugs (sonophoresis) 9‐11 . Here, we sought to determine whether such ultrasound facilitates the outward transport of analytes present in the interstitial fluid, thereby allowing noninvasive extraction of clinically useful analytes 12

Journal ArticleDOI
TL;DR: It is demonstrated that it may be possible to use a sequential anaerobic-aerobic process to completely degrade TBBPA in contaminated soils.
Abstract: Tetrabromobisphenol A (TBBPA) is a flame retardant that is used as an additive during manufacturing of plastic polymers and electronic circuit boards. Little is known about the fate of this compound in the environment. In the current study we investigated biodegradation of TBBPA, as well as 2,4,6-tribromophenol (TBP), in slurry of anaerobic sediment from a wet ephemeral desert stream bed contaminated with chemical industry waste. Anaerobic incubation of the sediment with TBBPA and peptone-tryptone-glucose-yeast extract medium resulted in a 80% decrease in the TBBPA concentration and accumulation of a single metabolite. This metabolite was identified by gas chromatography-mass spectrometry (GC-MS) as nonbrominated bisphenol A (BPA). On the other hand, TBP was reductively dehalogenated to phenol, which was further metabolized under anaerobic conditions. BPA persisted in the anaerobic slurry but was degraded aerobically. A gram-negative bacterium (strain WH1) was isolated from the contaminated soil, and under aerobic conditions this organism could use BPA as a sole carbon and energy source. During degradation of BPA two metabolites were detected in the culture medium, and these metabolites were identified by GC-MS and high-performance liquid chromatography as 4-hydroxybenzoic acid and 4-hydroxyacetophenone. Both of those compounds were utilized by WH1 as carbon and energy sources. Our findings demonstrate that it may be possible to use a sequential anaerobic-aerobic process to completely degrade TBBPA in contaminated soils.

Journal ArticleDOI
01 Jul 2000-Catena
TL;DR: In this article, the role of soil crusts in infiltration processes in three contrasting environments in the Northern, Central, and Central-Western Negev, Israel was examined, and it was shown that removal of a thin cyanobacterial-dominant crust from a sandy dune at Nizzana in the Central-western Negesv and of a well-developed lichendominant and a cyanobacteriadominant soil from a loess-covered hillslope at Sayeret Shaked in the northern Negesa resulted in three to fivefold increases in sorpt
Abstract: We examined the role of soil crusts in infiltration processes in three contrasting environments in the Northern, Central, and Central-Western Negev, Israel. The removal of a thin cyanobacterial-dominant crust from a sandy dune at Nizzana in the Central-Western Negev and of a well-developed lichen-dominant and a cyanobacterial-dominant crust from a loess-covered hillslope at Sayeret Shaked in the Northern Negev resulted in three to fivefold increases in sorptivity and steady-state infiltration under both ponding and tension. The removal of a depositional crust colonised by cyanobacteria from a loess floodplain at Sede Zin in the Central Negev resulted in an increased infiltration under tension, but had no significant effect under ponding. We attribute the lack of effect under ponding to exposure of surface silts to water, which resulted in the clogging of matrix pores and surface sealing. The removal of the crusts in all three landscapes influences resource flows, particularly the redistribution of runoff water, which is essential for the maintenance of desert soil surface patterning. It would also have marked effects on germination, establishment and survival of vascular plants and soil biota, leading ultimately to desertification.

Proceedings ArticleDOI
01 Sep 2000
TL;DR: Two methods for fingerprint image enhancement are proposed using a unique anisotropic filter for direct grayscale enhancement and show some improvement in the minutiae detection process in terms of either efficiency or time required.
Abstract: Extracting minutiae from fingerprint images is one of the most important steps in automatic fingerprint identification and classification. Minutiae are local discontinuities in the fingerprint pattern, mainly terminations and bifurcations. In this work we propose two methods for fingerprint image enhancement. The first one is carried out using local histogram equalization, Wiener filtering, and image binarization. The second method use a unique anisotropic filter for direct grayscale enhancement. The results achieved are compared with those obtained through some other methods. Both methods show some improvement in the minutiae detection process in terms of either efficiency or time required.

Journal ArticleDOI
TL;DR: The pH-sensitive hydrogel poly(HEMA-co-DMAEMA) can be manipulated to produce glucose-responsive insulin release system that is effective in reducing blood glucose levels.