Memory of incomplete phase transitions from a random squares model.

We present a simple two-dimensional model for a phase transition, then study its predictions, in particular the memory properties. The direct transformation is modeled by randomly placing small squares, "nuclei", on an initially empty surface. Then, the nuclei expand ("grow") up to finite final sizes which are randomly chosen in a given range, while keeping their square shape. An important issue is the "interaction" which forces some squares to remain at smaller sizes if the surrounding squares get in the way of their growth. Interestingly, this naturally leads to quasiequal total area covered by the squares of each size after a complete direct transformation. Next, it is shown that the system "remembers" incomplete ("arrested") reverse transformations taking place in reversed order of the squares sizes. The memory is "encrypted" in the distribution of the squares sizes after a next direct transformation and manifests as a significant imbalance between the areas covered by the "big" and "small" (relative to the arrest size) squares. We are able to also reproduce the so-called "hammer effect" and the memorizing of multiple arrest points. Our model is particularly relevant for the thermal memory effect in shape memory alloys, and we actually borrowed many features from existing thermodynamic models addressing this effect. However, here we eliminate the explicit thermodynamics and end up with a statistical geometry model, presumably easier to reproduce.

Electronic transmittance phase extracted from mesoscopic interferometers.

: The usual experimental set-up for measuring the wave function phase shift of electrons tunneling through a quantum dot (QD) embedded in a ring (i.e., the transmittance phase) is the so-called 'open' interferometer as first proposed by Schuster et al. in 1997, in which the electrons back-scattered at source and the drain contacts are absorbed by additional leads in order to exclude multiple interference. While in this case one can conveniently use a simple two-path interference formula to extract the QD transmittance phase, the open interferometer has also a number of draw-backs, such as a reduced signal and some uncertainty regarding the effects of the extra leads. Here we present a meaningful theoretical study of the QD transmittance phase in 'closed' interferometers (i.e., connected only to source and drain leads). By putting together data from existing literature and giving some new proofs, we show both analytically and by numerical simulations that the existence of phase lapses between consecutive resonances of the 'bare' QD is related to the signs of the corresponding Fano parameters - of the QD + ring system. More precisely, if the Fano parameters have the same sign, the transmittance phase of the QD exhibits a Π lapse. Therefore, closed mesoscopic interferometers can be used to address the 'universal phase lapse' problem. Moreover, the data from already existing Fano interference experiments from Kobayashi et al. in 2003 can be used to infer the phase lapses.

Depressive symptoms as a risk factor for osteoporosis and fractures in older Mexican American women.

INTRODUCTION AND HYPOTHESIS: Despite higher rates of depression, lower hormone replacement therapy (HRT) use, and inadequate knowledge of factors associated with osteoporosis, Mexican Americans have been understudied with regards to the association between depression, osteoporosis, and fractures. We hypothesized that depression increases the risk for osteoporosis and fractures among older Mexican American women. METHODS: Seven years of prospective data (1993-2001) from the Hispanic Established Populations for Epidemiologic Studies of the Elderly were analyzed for 1,350 women in the Southwest United States who had complete data for at least the first follow-up interview. RESULTS: Respondents (mean age:75) were generally poorly educated, had low income, and reported poor or fair health. High levels of depressive symptoms were reported by 31%, while new diagnosis of osteoporosis and new fractures were reported by 18 and 13%, respectively. Logistic regression analyses showed that predictors of newly diagnosed osteoporosis included age, high school (HS) education, ever having been an alcoholic, early menopause, hormone replacement therapy, and high levels of depressive symptoms. Factors predictive of new fractures included age, HS education, diabetes, early menopause, and high levels of depressive symptoms. CONCLUSIONS: Depressive symptoms were associated with increased risk of osteoporosis and new fractures, even after controlling for other predictive factors.

[A study on periodontal implications of the therapy for dento-maxillary anomalies]. / Studiu privind implicatiile parodontale ale terapiei anomaliilor dentomaxilare.

Dento-maxillary anomalies are the results of a deviation of growth processes, or of the development of the dento-maxillary apparatus. From the viewpoint of their frequencies the dento-maxillary anomalies hold the third place in the list of stomatological affections. The great variety of clinical manifestations of dento-maxillary anomalies has determined definition of therapeutical attitudes, in the frame of which therapy with orthodontal devices has an important place. This type of therapy exerts its effects also by implicating the parodontium, and this by at least two different mechanisms:-the induction of changes in the structures of the dento-maxillary apparatus by a direct parodontal mechanisms; as an element in the overall regulation of the growth of the dento-maxillary apparatus. The treatment with orthodontial devices should be conceived in such a way that it will protect the parodontium from the deleterious effects of these devices. The data presented further were obtained from 2 groups of patients and concern the improvement of the efficiency of treatments with orthodontal devices, and the protection of the parodontium during treatment. The first group was investigated in 1988, and criteria for the selection of participants in the second group were established. In the first group a total of 109 subjects were included, aged between 5 and 20 years, in whom stomatologic procedures were started in January 1988. These subjects were followed until the month of November of the same year. The most frequently encountered anomaly was maxillary compression (endalvellia) in 70 subjects. With regard to the condition of the marginal parodontium clinical exploration showed that 57 subjects had not underwent changes.(ABSTRACT TRUNCATED AT 250 WORDS)

[The clinical and technological particularities of using Gaudent "S" and Gaudor alloys in the conjoint treatment of extensive edentation]. / Studiul particularitatilor clinice si tehnologice ale utilizarii aliajelor Gaudent S si Gaudor în terapia conjuncta a edentatiilor întinse.

The present paper forms part of a longitudinal study on prostheses restaurations with Romanian non-noble alloys for establishing the clinical, technological and biological implications of their utilization in mass assistance. The large contact surface with biological structures and the buccal medium of total conjoint restaurations permitted chacking of previous data regarding the biological behaviour of these alloys. In the group of 58 patients with total bridges followed up for 2 to 5 years there were no adverse reactions in which the alloy used could be incriminated. The iatrogenic aspects observed consequent to the application of prostheses were common to the use of any other metal alloy. The surface colour changes in a reduced number of cases depended upon the technologic preparation of the alloys and particularly upon the patient's limited ability to keep the plate under bacterial control. The study demonstrated that casting of a total Gaudent S bridge under present conditions does not give correct adaptation of the cervical limits which means more accurate compliance with the technology and homologation of the specific of this alloy.

[Contribution of immediate orthopedic-orthodontic treatment in maxillo-palatine-labial clefts]. / Aportul tratamentului asociate ortopedico-ortodontic în despicaturile labio-maxilo-palatine.

Labio-maxillo-palatine clefts are pathological conditions accompanied by severe handicaps, congenital malformations of particular interest for medical assistance because of several reasons, including the following: they are the most frequent congenital malformations of the bucco-maxillo-facil region: in certain cases there are other teratologic conditions in other parts of the organism that are associated to these clefts; there are no disturbances from the intellectual viewpoint; there are efficient possibilities for therapy as a result of a multidisciplinary approach, and the progress achieved in each of the fields involved may contribute to continuous improvement of the therapeutical prognosis; because of the therapeutical problems that these pathological conditions may raise, and because of the long duration of the treatment, the pathology involved in labio-maxillo-palatine clefts has a special social character which renders necessary the support of extra-medical factors (special schooling, special conditions for work, etc.). All these aspects explain the world-wide interest for this type of pathology, as it is also reflected in the large number of scientific manifestations dedicated exclusively, or in association to this problem, aimed at achieving a permanent therapeutic progress in this field. In the period between 1986 and 1987 the authors have selected 60 patients out of those hospitalized for this defect in the Clinic. The patients were aged between 2 and 43 years. Orthodontal therapy is the type of therapy which takes the longest time in these patients. This is achieved by the successive application of orthodontal devices, which necessitate a long-term therapeutic strategy. In the course of this therapy a permanent cooperation is necessary between the specialist in orthodontics and the maxillofacial surgeon. A common approach is beneficial for both specialties. The number of specialists in orthodontics involved in the orthodontal therapy of labio-maxillo-palatine clefts is alarmingly low, and thus there is no possibility to evolve a special program for their further special education. Another difficulty is the fact that patients from all over the country demand the services of the same specialist, and a series of aspects evolve from this situation, as follows: the patients (usually accompanied by one of the parents) have to perform long trips, which are also expensive; when incidents occur, in relation with the use of a orthodontal device these patients cannot require immediately the assistance of specialized services, and, as a result, the number of recidives is alarmingly high.(ABSTRACT TRUNCATED AT 400 WORDS)