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Biomedical subjects

Y Silberberg

Publications and source records attributed to Y Silberberg.

18 recordsLinked to original sources
PubMed2003

Observation of mutually trapped multiband optical breathers in waveguide arrays.

Multiphoton fluorescence is used for the direct observation of a new class of breathers in waveguide arrays, which are a coherent superposition of Floquet-Bloch solitons of different bands. These Floquet-Bloch breathers oscillate along their spatial propagation axis, and possess several novel properties. Some behavior of these breathers is readily understood intuitively in terms of the band structure of the waveguide array and the properties of discrete solitons.

Journal Article↗
PubMed2003

Interactions of discrete solitons with structural defects.

We investigated the interaction of discrete solitons with defect states fabricated in arrays of coupled waveguides. We achieved attractive and repulsive defects by decreasing and increasing, respectively, the spacing of one pair of waveguides in an otherwise uniform array. Linear and nonlinear propagation in the same samples show distinctly different properties. The role of the Peierls-Nabarro potential in the interaction of the soliton with the defect is discussed.

Journal Article↗
PubMed2001

Kerr spatiotemporal self-focusing in a planar glass waveguide.

We observed simultaneous focusing in both space and time for light pulses propagating in a planar waveguide. In particular, 60 fs pulses with a width of 170 microm were injected into a planar glass waveguide in the anomalous dispersion regime. Output pulses as short as 30 fs and as narrow as 20 microm were measured. The results suggest that multiphoton absorption and intrapulse stimulated Raman scattering arrest the spatiotemporal contraction. The results were compared to the pulse evolution in zero and normal dispersion regimes and were shown to be significantly different. All of the experimental results were reproduced by a numerical model.

Journal Article↗
PubMed2001

Self-focusing and defocusing in waveguide arrays.

We show that two regimes of diffraction exist in arrays of waveguides, depending upon the input conditions. At higher powers, normal diffraction leads to self-focusing and to the formation of bright solitons through the nonlinear Kerr effect. By slightly changing the input conditions, light experiences anomalous diffraction and is nonlinearly defocused. For the first time, self-focusing and self-defocusing have been achieved for the same medium, structure, and wavelength.

Journal Article↗
PubMed2001

Transform-Limited Pulses Are Not Optimal for Resonant Multiphoton Transitions.

Maximizing nonlinear light-matter interactions is a primary motive for compressing laser pulses to achieve ultrashort transform limited pulses. Here we show how, by appropriately shaping the pulses, resonant multiphoton transitions can be enhanced significantly beyond the level achieved by maximizing the pulse's peak intensity. We demonstrate the counterintuitive nature of this effect with an experiment in a resonant two-photon absorption, in which, by selectively removing certain spectral bands, the peak intensity of the pulse is reduced by a factor of 40, yet the absorption rate is doubled. Furthermore, by suitably designing the spectral phase of the pulse, we increase the absorption rate by a factor of 7.

Journal Article↗
PubMed2000

Diffraction management

By using the diffraction properties of waveguide arrays, we propose a scheme to produce structures with designed diffraction. We fabricated arrays with reduced, canceled, and even reversed diffraction. Results of experiments with such waveguides are presented and compared with the predictions made by coupled-mode theory.

Journal Article↗
PubMed1990

Evaluation of a cancer prevention and detection continuing education program for nurses.

To stay relevant and continue to meet the needs it was created to meet, a 15-year-old continuing education program in cancer prevention and detection for nurses has found change a constant. The process it has followed in evaluation--identifying goals, gathering and analyzing data, and reporting the results--can be compared with the nursing process in which feedback prompts changes and initiates the evaluation process all over again. The most recent part of the program's ongoing evaluation involved 70 nurses enrolled in a three-week continuing education program in which the nurses were pretested and posttested to measure cognitive gain in nine content areas covered in classroom and clinical instruction. Paired t test scores showed overall that students' scores improved significantly, increasing a mean of 18% across all categories. These results indicate that students are gaining knowledge, and measures of skills, improving on those already in place, are being added in what is only the latest modification of a program shaped by feedback from students, faculty, and research.

Clinical Competence↗
PubMed1988

AIDS education.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Evaluation of fellowship and residency programs in a comprehensive cancer center.

A Dental Oncology residency and fellowship program was evaluated annually from 1980-1984 by each trainee. Nineteen training program variables were assessed on an Exit from Training Questionnaire using 0-100 mm linear scales. The five annual scores for each variable were subjected to trend analysis. Implication of the results to the training program are discussed. The evaluation method may be used to establish a departmental training program benchmark in relation to which future performance can be measured and as a guide to program modification. The method may be applied to all departmental training programs and, when combined, to the institution as a whole.

Cancer Care Facilities↗
PubMed1983

At the Developmental Therapeutics Clinic of a comprehensive cancer centre: cancer information needs of "visitors".

The survey of 150 "visitors" to the Developmental Therapeutics Clinic of the M.D. Anderson Hospital and Tumor Institute revealed that this population is composed of three distinct subpopulations, not only in terms of status in the clinic but also in terms of cancer information needs. New patients information needs vary greatly from those of patients familial with the clinic. Relatives and/or friends accompanying patients to the clinic present a set of information needs distinctly different from those of the other two groups. The three subpopulations are also different from each other along several other study dimensions. Among these are clarity of the tests and examinations performed, understanding cancer metastasis, fear of the tests, effects of discussion of the disease, and need for counseling. All three groups desire more communication with social workers and with chaplains rank second and third. Most participants in the study desire cancer information in pamphlets, while private discussions and films or television programmes are next on the priority list. When planning a hospital-based cancer education programme, careful attention must be paid to the differential needs of the population visiting various clinics. To better understand these needs, similar studies in other clinics are recommended.

Adolescent↗
PubMed1983

Attitudes and practices of families of children in treatment for cancer. A cross-cultural study.

A follow-up study was made of the prevalence of the use of unproven treatment methods by families of children being treated for cancer at UT M.D. Anderson Hospital. Information was also obtained about parental attitudes toward conventional and alternative treatments and their understanding of them, as well as the physicians' awareness of the use of alternative treatments. Cross-cultural comparisons were made to assess the differences between Hispanics and Anglos in their perceptions of treatment. Sixty-six parents responded to questionnaires (34 Anglo, 30 Hispanic, and two others), and the results in terms of prevalence of use were comparable to those obtained in an earlier study (less than 10%) at the same institution, as well as to those recently reported by investigators at another institution in northwestern U.S. No parents reported the use of Laetrile. Significant differences were found between the Anglos and Hispanics in their perceptions of the treatment administered at the hospital. A significant number of parents expressed a desire for more information from their physicians about all types of treatment. This study serves as a pilot project for a nationwide, multihospital study to be conducted in 1982.

Adult↗
PubMed1982

Information preferences of cancer patients ages 11-20 years.

This study investigates by written questionnaire the information sources preferred by 63 adolescent cancer patients. Physicians were the most common source. Over half preferred private discussions with a health professional over other formats, and 68% indicated physicians as the health professional of choice. Sixty-eight percent wanted parents included. Only 35% indicated that additional information would be personally helpful, while 42% and 45%, respectively, stated that families and friends should have more information. No relationship between diagnosis or sex and the patients' responses was found. Newly diagnosed patients were less likely to perceive physicians as their main information sources or want additional information. Patients in active illness phases were also less desirous of additional information. Younger patients were more likely to prefer information only from parents, to avoid group discussions, and to negate wanting friends to receive additional information. Hispanics were most likely to want parents to have additional information and to request parental inclusion in discussions.

Adolescent↗
PubMedDate not supplied

Sources of information about cancer as perceived by adolescent patients, parents, and physicians.

As survival time has been extended for young cancer patients, their informational needs have also increased. Using written questionnaires, we surveyed 63 adolescent patients, 60 parents, and 53 physicians to compare their perceptions of patient-communication patterns and current and preferred information sources. Physicians were the main current and preferred information sources noted by all three groups. Group discussions with patients the same age, films and television programs, and books were ranked as acceptable but less preferable sources by more than half of each group. More than 90% of the patients were usually accompanied by a parent. Patients most frequently sought their parents to discuss general concerns and cited parents as their second most frequently used source of disease-related information. Adolescents qualified their parental discussions more than was perceived by their parents (P less than 0.01) and viewed themselves as discussion initiators more frequently than did their parents (P less than 0.05). Parents were more likely than patients to prefer physicians as their child's information source (P less than 0.05). Physicians consistently underestimated their own and the parents' importance, believing instead that the patients relied more on peers. Fewer physicians than patients or parents favored including parents in discussion with health professionals (P less than 0.001).

Adolescent↗