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Biomedical subjects

S Ronen

Publications and source records attributed to S Ronen.

At least 19 recordsLinked to original sources
PubMed2006

Scattering length instability in dipolar Bose-Einstein condensates.

We predict a new kind of instability in a Bose-Einstein condensate composed of dipolar particles. Namely, a comparatively weak dipole moment can produce a large, negative two-body scattering length that can collapse the Bose-Einstein condensate. To verify this effect, we validate mean-field solutions to this problem using exact, diffusion Monte Carlo methods. We show that the diffusion Monte Carlo energies are reproduced accurately within a mean-field framework if the variation of the s-wave scattering length with the dipole strength is accounted for properly.

Journal Article↗
PubMed2003

Can the eigenstates of a many-body Hamiltonian be represented exactly using a general two-body cluster expansion?

It is proved that a recent conjecture that the exact ground-state wave function of an arbitrary many-fermion system with one- and two-body interactions may be represented by an exponential cluster expansion employing finite two-body operators, starting from any reference function sufficiently close to the exact eigenfunction, is not valid. We show that the space of initial reference functions which lead to the exact ground state is of dimension equal to the number of two-body operators. If the dimension of the multiparticle space is greater than the number of two-body operators, then the space of good reference functions is of measure zero in it.

Journal Article↗
PubMed1995

Gaucher's disease variant characterised by progressive calcification of heart valves and unique genotype.

Gaucher's disease is the most prevalent sphingolipid storage disease, characterised by substantial genetic and phenotypic variability. Cardiac manifestations are rare. We report 12 Arab Gaucher's disease patients, 2-20 years of age, who presented with oculomotor apraxia but only slight classic signs of the disease. All but the youngest had calcifications of the aortic or mitral valves or both. All these patients were homozygous for the rare point mutation D409H (1342C). Valvular calcifications increased with age and showed progression during 2 years of follow-up. Two of the oldest patients underwent aortic valve replacement, and one sibling had died suddenly at age 16, before this study, Corneal opacities were another common feature. The potentially fatal course of this Gaucher's disease variant, and the availability of a reliable PCR-based method for heterozygote detection, mean that population screening and genetic counselling in the geographic area at risk are important. Affected individuals should be closely monitored by echocardiography to gauge the need for valve replacement. The potential of enzyme replacement to prevent these cardiac complications cannot be ascertained at present, because of the high cost of therapy.

Adolescent↗
PubMed1989

Studies of the metabolism of human breast cancer spheroids by NMR.

Spheroids present a model for tumor behavior in vivo. In NMR studies, a problem of spheroid adhesion occurs. Here, we present a method which overcomes this problem and show the variations in phosphate metabolite concentrations as well as the rate of glucose metabolism as a function of spheroid age.

Adenosine Triphosphate↗
PubMed1988

A metabolic analysis of high myopia and senile macular degeneration.

Abnormal zinc and copper metabolism have been described in several retinal disorders affecting the retinal pigment epithelium. An infrequent presentation of senile macular degeneration in high myopia is well known. We examined the blood for zinc and copper and the urine for copper of three groups of patients, one consisting of high myopia, another with high myopia and primary retinal detachment and the other a group of patients with senile macular degeneration. When comparing the above groups of patients, we found statistically elevated values of serum zinc (p = less than 0.005) in the group of patients with senile macular degeneration. The significance of these findings, and a correlation with the pathogeneses of high myopia and senile macular degeneration is discussed.

Adult↗
PubMed1985

Treatment of ocular inflammation with diclofenac sodium: double-blind trial following cataract surgery.

A controlled trial of diclofenac sodium was carried out in 100 patients undergoing intracapsular cataract extraction. All patients were treated with dexamethasone eyedrops twice daily, plus either diclofenac sodium 50 mg tid or matching placebo tid, started 24 hours before surgery and continued for four weeks. In comparison with those in the placebo group, patients in the diclofenac group showed significant decreases in most signs of ocular inflammation. Diclofenac therapy was well tolerated, except in one patient, and may safely be used to reduce intraocular inflammation.

Aged↗
PubMed1983

Cortical blindness in infancy: a follow-up study.

Clinical data of 6 cases of cortical blindness in infancy were analyzed. The underlying brain damage was a result of hypoxic events occurring in the pre- or perinatal period, or shortly after birth. The long-term follow-up of the children showed that some visual recovery occurred but capacity of recognition remained impaired. Early diagnosis of this entity and adequate education will help the visual and psychomotor development of the child.

Birth Injuries↗
PubMed1983

Globular-like deformities of the cornea in a patient with dwarfism.

A family affected with pituitary dwarfism transmitted probably as an X-linked recessive or autosomal recessive condition, is described. The propositus had globular-like changes in his cornea, this latter as a sequela of endocrine disturbances, is suggested and discussed.

Abnormalities, Multiple↗
PubMed1981

The compressed work week as organizational change: behavioral and attitudinal outcomes.

The results from recent studies on the compressed work week have been compiled and categorized in order to provide some basis for generalizing the effects of the work schedule on employee attitudes and behavior. It appears that attitudes toward the compressed week are favorable, with some generalization to job attitudes. Performance outcomes are ambiguous, although there are no reported decreases; fatigue seems to be the only negative aspect of the longer day. An examination of mediating variables suggests more complex relationships between the implementation of the compressed work week and potential outcomes. These relationships are described and directions are indicated for future research.

Attitude↗
PubMed1981

Functional occlusion of a cilioretinal artery.

Functional occlusion of the cilioretinal artery in the presence of central vein occlusion is difficult to prove. We describe a case of central retinal vein occlusion in which cilioretinal artery occlusion developed after iatrogenic lowering of the blood pressure. Fluorescein angiography showed a peculiar hemodynamic sequence that demonstrated a functional origin to the cilioretinal artery occlusion.

Adult↗
PubMed1981

[Conjunctival ocular myosis (Oesterus ovis) about 3 cases (author's transl)].

Conjunctival lesions are the most frequent expression of ocular myiasis encountered in the Mediterranean region. Presenting typically with inflamed and oedematous eyes, and superficial corneal erosions, these affections are rarely diagnosed as they are excluded from the differential diagnosis. Early, adequate treatment will prevent major complications.

Adult↗
PubMed1980

Ankyloblepharon filiforme adnatum: congenital eyelid-band syndromes.

Three infants had congenital eyelid bands, ankyloblepharon filiforme adnatum (AFA), in association with cleft lip and palate. A review of the literature of all previously reported cases of AFA was performed and a new classification of the various clinical types of AFA is proposed. This new classification should aid in genetic counseling.

Abnormalities, Multiple↗
PubMed1980

Orbital inflammation: an unusual extraintestinal complication of shigellosis. Report of a case.

A case of unilateral exophthalmos with ophthalmoplegia and papilledema which developed 1 week after culture-proven Shigella sonnei dysentery is described. The clinical course with improvement of the patient's eye findings as well as systemic condition on appropriate antibiotic therapy probably demonstrate the relationship between the the dysentery and subsequent orbital inflammation.

Dysentery, Bacillary↗