Showing papers by "Ben-Gurion University of the Negev published in 1999"

Non‐destructive optical detection of pigment changes during leaf senescence and fruit ripening

Abstract: Reflectance spectra in the visible and near infra-red range of the spectrum, acquired for maple (Acer platanoides L.), chestnut (Aesculus hippocastanum L.), potato (Solanum tuberosum L.), coleus (Coleus blumei Benth.), leaves and lemon (Citrus limon L.) and apple (Malus domestica Borkh.) fruits were studied. An increase of reflectance between 550 and 740 nm accompanied senescence-induced degradation of chlorophyll (Chl), whereas in the range 400-500 nm it remained low, due to retention of carotenoids (Car). It was found that both leaf senescence and fruit ripening affect the difference between reflectance (R) near 670 and 500 nm (R 678 -R 500 ), depending on pigment composition. The plant senescing reflectance index in the form (R 678 - R 500 )/R 750 was found to be sensitive to the Car/Chl ratio, and was used as a quantitative measure of leaf senescence and fruit ripening. The changes in the index were followed during leaf senescence, and natural and ethylene-induced fruit ripening. This novel index can be used for estimating the onset, the stage, relative rates and kinetics of senescence/ripening processes.

Information Fusion in the Context of Multi-Document Summarization

Abstract: We present a method to automatically generate a concise summary by identifying and synthesizing similar elements across related text from a set of multiple documents. Our approach is unique in its usage of language generation to reformulate the wording of the summary.

Four-wave mixing with matter waves

Abstract: The advent of the laser as an intense source of coherent light gave rise to nonlinear optics, which now plays an important role in many areas of science and technology. One of the first applications of nonlinear optics was the multi-wave mixing1,2 of several optical fields in a nonlinear medium (one in which the refractive index depends on the intensity of the field) to produce coherent light of a new frequency. The recent experimental realization of the matter-wave ‘laser’3,4—based on the extraction of coherent atoms from a Bose–Einstein condensate5—opens the way for analogous experiments with intense sources of matter waves: nonlinear atom optics6. Here we report coherent four-wave mixing in which three sodium matter waves of differing momenta mix to produce, by means of nonlinear atom–atom interactions, a fourth wave with new momentum. We find a clear signature of a four-wave mixing process in the dependence of the generated matter wave on the densities of the input waves. Our results may ultimately facilitate the production and investigation of quantum correlations between matter waves.

Cerebrospinal cytokine levels in patients with acute depression.

Abstract: There is increasing evidence for an association between the alteration of cytokine concentrations in blood and the pathophysiology of depressive disorders. Studies in humans have not investigated CSF

Reasoning with conditional ceteris paribus preference statements

Abstract: In many domains it is desirable to assess the preferences of users in a qualitative rather than quantitative way. Such representations of qualitative preference orderings form an important component of automated decision tools. We propose a graphical representation of preferences that reflects conditional dependence and independence of preference statements under a ceteris paribus (ali else being equal) interpretation. such a representation is often compact and arguably natural. We describe several search algorithms for dominance testing based on this representation; these algorithms are quite effective, especially in specific network topologies, such as chain- and treestructured networks, as well as polytrees.

Modified CTAB Procedure for DNA Isolation from Epiphytic Cacti of the Genera Hylocereus and Selenicereus (Cactaceae)

Abstract: We present a simple protocol for DNA isolation from climbing cacti, genera Hylocereus and Selenicereus. The abundant polysaccharides present in Hylocereus and Selenicereus species interfere with DNA isolation, and DNA extracts, rich in polysaccharides, are poor templates for amplification using polymerase chain reaction (PCR). We used roots as the source tissue due to the lower viscosity of the extracts relative to that of other tissues. The extraction and isolation procedure we devised consists of the following steps: (1) three washes of ground tissue with the extraction buffer to remove the polysaccharides; (2) extraction with high-salt (4 M NaCl) cetyltrimethylammonium bromide (CTAB) buffer to remove the remaining polysaccharides; (3) removal of RNA by RNase; (4) phenol:chloroform extraction to remove proteins; (5) chloroform extraction to remove remaining phenols. The yields ranged from 10 to 20 μg DNA/g fresh roots. DNA samples prepared by our method were consistently amplifiable in the RAPD reaction and gave reproducible profiles.

Detection of Brucellae in Blood Cultures

Abstract: Brucellae are small gram-negative nonmotile coccobacilli which can be isolated as part of the normal flora of the genitourinary tract of a variety of wild and domestic animals including cows, goats, sheep, pigs, and dogs ([22][1],[34][2]). The organism is strictly aerobic, nonencapsulated, and

Inhibition of return in spatial attention: direct evidence for collicular generation.

Abstract: Visuomotor pathways in the vertebrate midbrain mediate rapid, reflexive orienting to abrupt changes. Using the 'inhibition of return' (IOR) mechanism, the attentional system favors novel spatial locations by inhibiting already scanned ones1. In a rare patient with a unilateral lesion restricted to the dorsal midbrain, we demonstrate that IOR is generated within the midbrain superior colliculus.

Orchestrating Rent Seeking Contests

Abstract: Contests have different, sometimes quite complex, organisational structures In particular, while most of the existing literature focusses on simultaneous contests, multistage contests are also quite frequently encountered This paper seeks to provide a rationale for the latter by endogenising the choice of a contest structure, which is made by an organiser of a contest interested in maximising the efforts expended by the contenders

Changes in pigments profile in the green alga Haeamtococcus pluvialis exposed to environmental stresses

Abstract: Haematococcus green culture starved for either nitrogen or phosphate accumulated astaxanthin up to 4% cell dry wt (2.6 g l−1). While under nitrogen starvation astaxanthin accumulation was faster (maximum achieved after 8 days in comparison to 14 days in the phosphate-starved culture) and accompanied by a drop in the chlorophyll content per cell down to 50% of its original value (30 pg cell−1); in the phosphate-starved culture this parameter did not change. HPLC profiles of carotenoids monitored along the starvation process revealed that astaxanthin esters accounted for more than 99% of total carotenoids at the end of the exposure period at both starvations.

The use of fibrin tissue adhesive to reduce blood loss and the need for blood transfusion after total knee arthroplasty. A prospective, randomized, multicenter study.

Abstract: Background: Total knee arthroplasty is associated with major postoperative blood loss of approximately 800 to 1200 milliliters, and blood transfusion is frequently required. With the increased concern about the risks of blood transfusion, various methods of blood conservation in orthopaedic surgery have been studied. The most appropriate solution, however, is to reduce the loss of blood during and after an operation. The present prospective, controlled, randomized study was designed to evaluate the hemostatic efficacy of the use of fibrin tissue adhesive in patients managed with total knee arthroplasty. Methods: Fifty-eight patients who were scheduled to have a total knee arthroplasty were randomly divided into two groups: a control group, in which the standard means of hemostasis were applied, and a treatment group, in which the standard means to control local bleeding were applied and a fibrin tissue adhesive was sprayed on the internal aspects of the operative field before skin closure. All operations were performed in a bloodless field with use of a pneumatic tourniquet. All patients received low-molecular-weight heparin as thromboprophylaxis twelve hours before the operation and every twelve hours postoperatively. Blood loss during the operation was evaluated by measuring the volume in the suction apparatus and by estimating the amount of lost blood in the swabs at the end of the operation. The apparent postoperative lost blood was determined by measuring the volume in the suction-drain bottles. All blood transfusions were recorded. Results: The mean apparent postoperative blood loss (and standard deviation) in the fibrin-tissue-adhesive group was 360 ± 287.7 milliliters compared with 878 ± 403.0 milliliters in the control group, with a mean difference of 518 milliliters (p < 0.001). The decrease in the level of hemoglobin was 25 ± 10 grams per liter in the treatment group compared with 37 ± 12 grams per liter in the control group (p < 0.001). Sixteen patients (55 percent) in the control group required a blood transfusion and eight (28 percent) required two units of blood, whereas only five (17 percent) of the patients in the fibrin-tissue-adhesive group required a blood transfusion and only one (3 percent) required two units (p = 0.004). The number of adverse events was comparable between the two groups. None of the adverse events were considered to be related to the use of fibrin tissue adhesive. One death, which was due to massive pulmonary embolism, was reported in the control group. No seroconversion was reported at three and six months after the operation. Conclusion: The use of fibrin tissue adhesive in total knee arthroplasty seems to be an effective and safe means with which to reduce blood loss and blood-transfusion requirements. Furthermore, the importance of these findings was enhanced by a significant reduction in blood loss, in the postoperative decrease in the level of hemoglobin, and in blood-transfusion requirements despite preoperative thromboprophylaxis with low-molecular-weight heparin.

Finding families for genomic ORFans.

Abstract: ‘Why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms?’ Charles Darwin, in The Origin of Species, Chapter 6: Difficulties in Theory The complete sequences of over a dozen microbial genomes are now known. At first glance roughly one-third of the protein encoding regions (ORFs) in each genome have no detectable sequence similarity to proteins of other genomes. Why, if proteins in different organisms have descended from common ancestral proteins by duplication and adaptive variation, do so many today show no similarity to each other? In this commentary we refer to these orphan ORFs as ‘ORFans’ and ask why there are so many, and how they can be assigned to known protein families. As a first step in solving the puzzle of why there are so many genomic ORFans, we have investigated some trivial explanations.

‘Ethnocracy’: The Politics of Judaizing Israel/Palestine

Abstract: During Israel’s fiftieth year of independence (1997-98), the country’s High Court of Justice was grappling with an appeal known as Qa'adan Vs Katzir. It was lodged by a Palestinian-Arab citizen who was prevented from leasing state land in the suburban locality of Katzir – built entirely on state lands -on grounds of not being a Jew.2 The court deferred decision on the case as much as it could. Its President, Justice Aharon Barak, known widely as a champion of civil rights, noted that this case has been among the most strenuous in his legal career, and pressured the sides to settle out of court. In March 2000 the court ruled in favor of Qa'adan, and noted that Israel's policies towards the Arab minority were discriminatory and illegal. Yet, the court did not issue an order to Katzir to let Qa'adan lease the land, and was very careful to limit the ruling to this specific case, so as not to create a precedent. In addition, the local Jewish community continued to raise administrative and social obstacles and frustrate Qa'adan's plans to join the locality. By mid 2005 the family has not moved as yet to Katzir. The fact that in Israel’s fiftieth year, the state’s highest legal authority still finds it difficult to protect a basic civil right such as equal access of all citizens to state land, provides a telling starting point for pursuing the goals of this paper. In the pages below I wish to offer a new conceptual prism through which the formation of Israel’s regime and its ethnic relations can be explained. A theoretical and empirical examination of the Israeli regime leads me to argue that it should be classified as an ‘ethnocracy’. The paper begins with a theoretical account of ethnocratic regimes, which are neither authoritarian nor democratic. Such regimes are states that maintain a relatively open government, yet facilitate a non-democratic seizure of the country and polity by one ethnic group. A key conceptual distinction is elaborated in the paper between ethnocratic and democratic regimes. Ethnocracies, despite exhibiting several democratic features, lack a democratic structure. As such, they tend to breach key democratic tenets, such as equal citizenship, the existence of a territorial political community (demos), universal suffrage, and protection against the tyranny of the majority. Following the theoretical discussion, the paper traces the making of the Israeli ethnocracy, focussing on the major Zionist project of Judaizing Israel/Palestine. The predominance of the Judaization project has spawned an institutional and political structure that undermines the common perception that Israel is both Jewish and democratic.3 The Judaization process is also a major axis along which relations between various Jewish and Arab ethno-classes can be explained. The empirical

Lycopene and 1,25-dihydroxyvitamin D3 cooperate in the inhibition of cell cycle progression and induction of differentiation in HL-60 leukemic cells.

Abstract: Lycopene, the major tomato carotenoid, has been found to inhibit proliferation of several types of cancer cells, including those of breast, lung, and endometrium. By extending the work to the HL‐60 promyelocytic leukemia cell line, we aimed to evaluate some mechanistic aspects of this effect. Particularly, the possibility was examined that the antipro‐liferative action of the carotenoid is associated with induction of cell differentiation. Lycopene treatment resulted in a concentration‐dependent reduction in HL‐60 cell growth as measured by [3H]thymidine incorporation and cell counting. This effect was accompanied by inhibition of cell cycle progression in the G0/G1 phase as measured by flow cytometry. Lycopene alone induced cell differentiation as measured by phorbol ester‐dependent reduction of nitro blue tetrazolium and expression of the cell surface antigen CD14. Results of several recent intervention studies with β‐carotene, which have revealed no beneficial effects of this carotenoid, sugge...

Hybrid fold recognition: combining sequence derived properties with evolutionary information.

Abstract: Recent assessments of structure prediction have demonstrated that (i) although fold recognition methods can often identify remote similarities when standard sequence search methods fail, the score of the top-ranking fold is not always significant enough to allow a confident prediction; (ii) the use of structural information such as secondary structure increases recognition accuracy; (iii) modern sequence-based methods incorporating evolutionary information from neighboring sequences can often identify very remote similarities; (iv) there is no one single method that is superior to other methods when evaluated over a wide range of targets, and (v) extensive human-expert intervention is usually required for the most difficult prediction targets. Here, I describe a new, hybrid fold recognition method that incorporates structural and evolutionary information into a single fully automated method. This work is a first attempt towards the automation of some of the processes that are often applied by human predictors. The method is tested with two cases that are often applied by human predictors. The method is tested with two fold-recognition benchmarks demonstrating a superior performance. The higher sensitivity and selectivity enable the applicability of this method at genomic scales.

Dopamine D4 receptor (D4DR) and serotonin transporter promoter (5-HTTLPR) polymorphisms in the determination of temperament in 2-month-old infants.

Abstract: We and others have previously shown that the dopamine D4 exon III repeat (D4DR) and the serotonin-transporter promoter region (5-HTTLPR) polymorphisms are not only associated with adult personality traits1-7 but also with temperament in 2-week-old neonates.8 We now report the results of a second study of these infants and their temperament at 2 months using Rothbart's Infant Behavior Questionnaire (IBQ).9 There were significant negative correlations between neonatal orientation and motor organization as measured by the Neonatal Behavioral Assessment Scale (NBAS)10 at 2 weeks and negative emotionality, especially distress in daily situations, at 2 months of age. There were significant main effects for negative emotionality and distress when the infants were grouped by the D4DR and the 5-HTTLPR polymorphisms. Infants with long D4DR alleles had significantly lower scores on Negative Emotionality (F[1, 72] = 8.50, P = 0.005) and Distress to Limitations (F[1,72] = 4.93, P = 0.03) than infants with short D4DR alleles. In contrast, infants with the short homozygous (s/s) 5-HTTLPR genotype had higher scores on Negative Emotionality (F[1,72] = 3.88, P = 0.053) and Distress to Limitations (F[1,72] = 4.94, P = 0.029) than infants with the I/s or I/I genotypes. The strongest effects occurred in those infants with the s/s 5-HTTLPR polymorphism who also were lacking long D4DR alleles which in some studies has been linked to adult novelty seeking.1,6 These infants showed most negative emotionality and most distress to daily situations, temperament traits that are perhaps the underpinning of adult neuroticism.

Visualization of membrane domains in Escherichia coli

Abstract: Bacterial membrane and nucleoids were stained concurrently by the lipophilic styryl dye FM 4-64 [N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl) hexatrienyl)pyridinium dibromide] and 4',6-diamidino-2-phenylindole (DAPI), respectively, and studied using fluorescence microscopy imaging. Observation of plasmolysed cells indicated that FM 4-64 stained the inner membrane preferentially. In live Escherichia coli pbpB cells and filaments, prepared on wet agar slabs, an FM 4-64 staining pattern developed in the form of dark bands. In dividing cells, the bands occurred mainly at the constriction sites and, in filaments, between partitioning nucleoids. The FM 4-64 pattern of dark bands in filaments was abolished after inhibiting protein synthesis with chloramphenicol. It is proposed that the staining patterns reflect putative membrane domains formed by DNA-membrane interactions and have functional implications in cell division.

Does the stock market predict real activity? Time series evidence from the G-7 countries

Abstract: This paper extends one aspect of the US stock market study of Fama (1990) and Schwert (1990). We examine the relationship between industrial production (IP) growth rates and lagged real stock returns for the G-7 countries using both in-sample cointegration and error-correction models and the out-of-sample forecast-evaluation procedure of Ashley et al. (1980). The cointegration tests show a long-run equilibrium relationship between the log levels of IP and real stock prices, while the error-correction models indicate a correlation between IP growth and lagged real stock returns for all countries except Italy. The out-of-sample tests show that in several sub-periods the US, UK, Japanese, and Canadian stock markets enhance predictions of future IP. ” 1999 Elsevier Science B.V. All rights reserved.

Scale invariance, new inflation and decaying λ-terms

Abstract: Realizations of scale invariance are studied in the context of a gravitational theory where the action (in the first-order formalism) is of the form $S =\int L_1\Phi d^4 x +\int L_2\sqrt{-g} d^4x$ where Φ is a density built out of degrees of freedom, the "measure fields" independent of gμν and matter fields appearing in L1, L2. If L1 contains the curvature, scalar potential V(ϕ) and kinetic term for ϕ, L2 another potential for ϕ, U(ϕ), then the true vacuum state has zero energy density, when theory is analyzed in the conformal Einstein frame (CEF), where the equations assume the Einstein form. Global scale invariance is realized when V(ϕ)=f1eαϕ and U(ϕ)=f2e2αϕ. In the CEF the scalar field potential energy Veff(ϕ) has, in addition to a minimum at zero, a flat region for αϕ→∞, with nonzero vacuum energy, which is suitable for either a new inflationary scenario for the early universe or for a slowly rolling decaying Λ-scenario for the late universe, where the smallness of the vacuum energy can be understood ...

CAFASP‐1: Critical assessment of fully automated structure prediction methods

Abstract: The results of the first Critical Assessment of Fully Automated Structure Prediction (CAFASP-1) are presented. The objective was to evaluate the success rates of fully automatic web servers for fold recognition which are available to the community. This study was based on the targets used in the third meeting on the Critical Assessment of Techniques for Protein Structure Prediction (CASP-3). However, unlike CASP-3, the study was not a blind trial, as it was held after the structures of the targets were known. The aim was to assess the performance of methods without the user intervention that several groups used in their CASP-3 submissions. Although it is clear that "human plus machine" predictions are superior to automated ones, this CAFASP-1 experiment is extremely valuable for users of our methods; it provides an indication of the performance of the methods alone, and not of the "human plus machine" performance assessed in CASP. This information may aid users in choosing which programs they wish to use and in evaluating the reliability of the programs when applied to their specific prediction targets. In addition, evaluation of fully automated methods is particularly important to assess their applicability at genomic scales. For each target, groups submitted the top-ranking folds generated from their servers. In CAFASP-1 we concentrated on fold-recognition web servers only and evaluated only recognition of the correct fold, and not, as in CASP-3, alignment accuracy. Although some performance differences appeared within each of the four target categories used here, overall, no single server has proved markedly superior to the others. The results showed that current fully automated fold recognition servers can often identify remote similarities when pairwise sequence search methods fail. Nevertheless, in only a few cases outside the family-level targets has the score of the top-ranking fold been significant enough to allow for a confident fully automated prediction. Because the goals, rules, and procedures of CAFASP-1 were different from those used at CASP-3, the results reported here are not comparable with those reported in CASP-3. Nevertheless, it is clear that current automated fold recognition methods can not yet compete with "human-expert plus machine" predictions. Finally, CAFASP-1 has been useful in identifying the requirements for a future blind trial of automated served-based protein structure prediction.