bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Effects of Faith-Based Coping on Physical and Mental Fatigue in Middle-Aged and Older Cardiac Patients
Authors: Al Amy L. , Peterson Christopher , Tice Terrence N. , Rodgers Willard , Seymour E. Mitchell , Bolling Steven F.
Published: February 2007

Purpose:

This analysis investigated the effect of faith-based coping used by cardiac patients undergoing surgery on physical and mental fatigue, symptoms which have significant prognostic implications for mortality. Particularly, we explored whether this faith effect is independent or explained by positive mediators.

Methods:

Two weeks preoperatively, 481 patients (male, 58%; mean age=62 years) were recruited for three sequential interviews. Among them, 426 completed the second interview, and 335 completed the post-operative follow-up. Cross-clamp and bypass time were obtained from patients' charts. Plasma interlukin-6 (IL-6) was used as a correlate of age-associated diseases and frailty.

Results:

Hierarchical multiple regression analyses showed that pre-operative positive religious coping styles and optimism contributed to reduced physical fatigue, controlling for post-operatively confirmed prayer coping and such covariates as severe injury. Depression and lower-back problems contributed to mental fatigue. No potential mediators explained these effects.

Conclusion:

Faith-based coping and optimism are independent predictors of physical fatigue.
Reifying Human Difference: The Debate on Genetics, Race, and Health
Authors: Braun Lundy
Published: February 2007

The causes of racial and ethnic inequalities in health and the most appropriate categories to use to address health inequality have been the subject of heated debate in recent years. At the same time, genetic explanations for racial disparities have figured prominently in the scientific and popular press since the announcement of the sequencing of the human genome. To understand how such explanations assumed prominence, this essay analyzes the circulation of ideas about race and genetics and the rhetorical strategies used by authors of key texts to shape the debate. The authority of genetic accounts for racial and ethnic difference in disease, the author argues, is rooted in a broad cultural faith in the promise of genetics to solve problems of human disease and the inner truth of human beings that is intertwined with historical meanings attached to race. Such accounts are problematic for a variety of reasons. Importantly, they produce, reify, and naturalize notions of racial difference, provide a scientific rationale for racially targeted medical care, and distract attention from research that probes the complex ways in which political, economic, social, and biological factors, especially those of inequality and racism, cause health disparities.
African-American Retention within a Community College: Differences in Orientation Course Enrollment
Authors: Derby Dustin C. , Watson Lemuel W.
Published: February 2007

Investigation of orientation programs and African-American student retention, particularly within the community college sector, has long been neglected. This study specifically investigates the differences between an orientation course and student retention measures, for African-American student retention. Chi-square analysis revealed significant differences for orientation course enrollment, student retention, and persistence.
Racial Differences in Attitudes toward Euthanasia
Authors: Wasserman Jason , Clair Jeffrey Michael , Ritchey Ferris J.
Published: February 2007

This article examines racial differences in attitudes toward euthanasia. Many researchers assert distrust of medicine as a substantive explanation for less favorable attitudes toward euthanasia among African Americans, although quantitative measurement has been unsuccessful in showing this. In this article, spiritual meaning, perceived capacity for discrimination (distrust), individual experiences with physicians, and access to healthcare are hypothesized as intervening variables in the relationship between race and attitudes toward euthanasia. With a distinction between individual and collective experiences with discrimination we use path analysis to test previous assertions that African American distrust of medicine leads to more negative attitudes toward euthanasia. Results indicate that while African Americans exhibit higher levels of distrust of medicine, this is not related to attitudes toward euthanasia, which seem predominantly to be a spiritual matter. Our findings have implications for legislative policy, treatment interventions, doctor-patient relations, and sociological understanding of the interaction of race, spirituality, experience, and attitudes.
Variables Affecting Patient Satisfaction in Breast Surgery: A Cross-Sectional Sample of Turkish Women with Breast Cancer
Authors: Noyan M. Aysin , Sertoz Ozen Onen , Elbi Hayriye , Kayar Ragip , Yilmaz Rasih
Published: February 2007

Objective:

In Turkey, despite the fact that breast cancer accounts for 24.1% of all cancer in women, a very small number of these patients receive breast reconstruction. This low percentage would seem to indicate that there are several factors affecting the decision of which surgical procedure should be selected. The aim of this study was to establish the demographical, medical, and psychological factors associated with the breast cancer patient's decision-making process, and assess their satisfaction with the type of surgery received.

Method:

We assessed long-term satisfaction with the type of surgery received; satisfaction with the information process by which the surgery decision is taken; feelings of ambivalence or regret regarding the type of surgery received in both mastectomy ( n = 50) and breast reconstruction patients ( n = 25). Additionally, breast cancer survivors were compared with age-matched healthy control volunteers ( n = 50) in terms of demographics, body image and self-esteem, which could be expected to affect their preferences. We administered a demographical and medical information form, Structured Clinical Interview for DSM-IV, Clinical Version (SCID-I), the Body Cathexis Scale (BCS); and the Rosenberg Self-Esteem Scale (RSE).

Results:

In both groups, women with a low income and less education were more likely to experience decision regret or low satisfaction. Moreover, total mastectomy-alone patients had lower self-esteem compared to reconstructive surgery patients and healthy women.

Conclusion:

Early stage breast cancer is a chronic disease and patients have to live with the consequences of their decision for many years. At the same time, the type of surgery is decided on when patients are in an acute phase and under intense pressure. Therefore, the decision making process needs to be explored more, especially breast cancer patients with less education and low income need better assistance and more detailed explanation of their options.
Explaining Paralysis in Chile's Health Sector, 1990–2000
Authors: Pushkar
Published: February 2007

This article looks at the health sector in Chile between 1990 and 2000 to examine the obstacles that policymakers face in implementing reforms. Given that the health sector is highly politicized, it is important to pay attention not only to what kind of reforms are needed but even more to how the desired reforms may be implemented. The author identifies the key actors in the Chilean health sector and shows how the given politico-institutional context allowed them to obstruct reforms. As a result, the health sector came to be characterized by paralysis, despite widespread recognition that reforms were needed, and despite an awareness that large numbers of Chileans were more concerned about health than political issues.
Ruminating about Symbolic Conflict through Imagined Interactions
Authors: Allen Terre H. , Berkos Kristen M.
Published: February 2007

Functional theory, as conceptualized by Dance and Larson [1], provided the framework for examining how individuals utilize imagined interactions to link conflict episodes. Proactive and retroactive functions of imagined interactions were conceptualized as a vehicle through which the mentation function of communication is accomplished. As such, the current study sought to determine the amount of conflict participants reported in their imagined interactions, the reported interaction partners, the amount of conflicts that were linked to one another, the level of the conflict, use of verbally aggressive messages in the imagined interactions, and the amount of physical aggression reported in participants' imagined interactions. Overall, results indicated that behavioral, normative, and personal level conflicts are routinely experienced, symbolically, through imagined interactions. Conflict partners included a variety of individuals, but mainly significant others, friends, and bosses. Moreover, results indicated that individuals use proactive and retroactive imagined interactions to link conflict episodes, and conflictual imagined interactions are characterized, to some degree, by verbally aggressive messages and to a lesser extent by incidents of physical violence.
Measurement of Importance in a Student Satisfaction Questionnaire: Comparison of the Direct and Indirect Methods for Establishing Attribute Importance
Authors: Roszkowski Michael J. , Ricci Raymond
Published: February 2007

Student dissatisfaction with certain aspects of college has been linked to attrition. Some developers of satisfaction surveys contend that in addition to satisfaction ratings, the questionnaire should contain an importance scale because dissatisfaction with the less important aspects of college is not as problematic as dissatisfaction with the more important aspects. Critics of importance ratings argue that they are unnecessary because respondents implicitly consider the importance of an attribute when formulating their satisfaction judgment. It may be possible to keep the length of the questionnaire shorter and still infer the importance of the attributes by examining the correlations between attributes and the measure of overall satisfaction. The attributes with the higher correlations with overall satisfaction are thought to be more important than attributes with low correlations with overall satisfaction. Questions remain about whether the relationship between importance and satisfaction exists and whether it is linear or non-linear in nature. The purpose of this study was to determine: 1) the type of relationship that exists between satisfaction and importance in a student satisfaction survey; and 2) the interchangeability of the direct and the inferred means of assessing attribute importance. It was found that in a student satisfaction survey, the relationship between satisfaction and importance is nonlinear. Attributes with very high or very low satisfaction are rated as more important than attributes with middle levels of satisfaction. The direct method of measuring importance was compared to three indirect methods (i.e., based on satisfaction). The three indirect methods differed in terms of how the overall satisfaction was determined (single item rating of general satisfaction, sum score of 25 attributes, and a question about whether the student would enroll at the same institution if given the chance to do it over again). The correlations between the direct and the indirect methods for determining attribute importance were at best only moderate. The indirect method most similar to the direct approach was the one-item general satisfaction question, but common method variance may be a factor in this. It was concluded that the direct and indirect methods should not be considered interchangeable. We recommended that future research determine which method is most valid by considering the relationship of each method to actual attrition.
The Effects of Web-Based Reading Curriculum on Children's Reading Performance and Motivation
Authors: Cole Juanita Mclean , Hilliard Veleshia Rhonda
Published: February 2007

This study investigated the benefits of using a Web-based reading curriculum program featuring music and video, on struggling readers' performance and motivation. A sample of 36 third grade students from low socioeconomic backgrounds was randomly assigned to receive Web-based or traditional reading instruction. Analyses of performance indicated basic reading skills improved significantly higher for students who received Web-based rather than traditional instruction. Results also showed a significant correlation between reading performance and motivation among struggling readers. Qualitative differences in motivation and engagement were observed across ethnicity among students who received Web-based instruction. The results and educational implications are discussed in relation to the cultural relevance of computer and non-computer-based learning environments.
The Effect of Exercise on Hippocampal Integrity: Review of Recent Research
Authors: Kiraly Michael A. , Kiraly Stephen J.
Published: February 2007

Objectives:

To review salient basic research regarding physical exercise as a major protective factor against hippocampal degradation and to emphasize its relevance to humans.

Method:

Recent mammalian and human research literature search and theoretical discussion.

Results:

The cascade of cellular damages from oxidative stress, nitrosative stress and gluco-corticoid effects are cumulative and age related. Exercise training reduces oxidative stress, nitro-sative stress and improves neuroendocrine autoregulation which counteracts damages from stress- and age-related neuronal degeneration, brain ischemia and traumatic brain injury. Conversely, lack of exercise and motility restrictions are associated with increased vulnerability from oxidative stress, nitrosative stress and glucocorticoid excesses, all of which precede amyloid deposition and are fundamental in the cascade of events resulting in neuronal degradation, especially in the hippocampi.

Conclusions:

Despite the paucity of human research, basic animal models and clinical data overwhelmingly support the notion that exercise treatment is a major protective factor against neurodegeneration of varied etiologies. The final common pathway of degradation is clearly related to oxidative stress, nitrosative stress, glucocorticoid dysregulation, inflammation and amyloid deposition. We conclude that people prone to chronic distress, brain ischemia, brain trauma, and the aged are at increased risk for neurodegenerative diseases such as Alzheimer's. Exercise training may be a major protective factor but without clinical guidelines, its prescription and success with treatment adherence remain elusive.
The School-to-College Transition in the Context of Educational Reform: Student Retention and the State Policy Process
Authors: Welsh John F. , Petrosko Joseph , Taylor Hal
Published: February 2007

This study examines the impact of state-level educational reform in Kentucky on college student retention. By tracking the educational progress of students who graduated from high school in a large school district and who subsequently enrolled in a research university in the same metropolitan area, the study reveals that the accountability measures and policy tools embedded in the educational reform effort contribute little to the prediction of student retention. The analysis questions the viability of state-driven reforms to improve the retention of students transitioning from high school to college in Kentucky and suggests that high schools and colleges may be able to improve student retention through the development of student information systems that are based on concept of “supply chain management.”
Multimodal Therapy of Treatment Resistant Depression: A Study and Analysis
Authors: Bannan Noreen
Published: February 2007

Objective:

To demonstrate through the use of a case study, the application of cognitive psychotherapy in the treatment of resistant depression.

Method:

The case of a woman with an 18-month history of resistant depression associated with low self-esteem, guilt and shame, who failed to respond to three therapeutic trials of antidepressants is described. A detailed description of a CBT intervention over 12 sessions is given.

Result:

Clear improvements on assessments of mood and hopelessness, along with overall improvements in social and occupational functioning were noted.

Conclusion:

These improvements were attributed to a combination of CBT and pharmacotherapy, where pharmacotherapy alone failed to alleviate symptoms. A concise literature review revealed relatively few published trials of psychological treatments, and a lack of clear guidelines on pharmacological treatments. More research is needed to explore the efficacy of psychological therapies for treatment resistant depression.
When Family Planning Services Fail: Experience from Bangladesh
Authors: Rob Ubaidur , Piet-Pelon Nancy , Mutahara Marium Ul
Published: February 2007

Unwanted pregnancy continues to be a major problem in Bangladesh, despite a steady increase in contraceptive use over the last two decades. Abortion is illegal in Bangladesh but menstrual regulation (MR) is routinely provided through health services. The 1999–2000 Bangladesh Demographic and Health Survey (BDHS) data indicate that approximately 5% of currently married women had ever received MR services. Service statistics suggest a rising trend in MR and induced abortion, which is expected to decline as contraceptive use rate increases. It is observed that knowledge of MR had not significantly increased over time and women did not differentiate between MR and abortion. Findings from case studies suggest that in most cases husbands have supported decisions regarding both contraception and pregnancy termination. Understanding the experiences of MR users will help service providers to identify problems faced by a particular group of women who desperately need quality reproductive health services.
Understanding the Student-Faculty Mentoring Process: Its Effects on At-Risk University Students
Authors: Santos Silvia J. , Reigadas Elena T.
Published: February 2007

The purpose of this investigation was to understand the student-faculty mentoring process and how mentoring relationships facilitate at-risk students' adjustment to college. The sample consisted of 65 college students who were involved in a Faculty Mentoring Program (FMP) at a four-year institution. A conceptual model was tested relating ethnic homogeneity in student-mentor backgrounds and frequency of student-mentor contact to perceived mentor supportiveness, students' attitudinal adjustment to college, students' academic performance, and level of satisfaction with the FMP. Results of the path analysis revealed that students with mentors of the same ethnicity met more frequently with their faculty mentors and, in turn, viewed mentors as being more supportive in furthering their career and personal development and expressed greater satisfaction with their participation in the FMP. Likewise, student-mentor ethnic homogeneity and frequency of student-mentor contact directly influenced students' attitudinal adjustment to college and, in turn, impacted positively on students' academic performance and satisfaction with the FMP. The findings are discussed in terms of Social Network Theory.
Programa Shortstop: A Culturally Focused Juvenile Intervention for Hispanic Youth
Authors: Cervantes Richard C. , Ruan Karen , Dueñas Norma
Published: February 2007

Culturally sensitive juvenile delinquency and substance abuse interventions are relatively limited and unavailable to many first-time Hispanic juvenile offenders. The purpose of this study was to test the effectiveness of a culturally focused juvenile and substance abuse intervention program for first time Hispanic youth offenders. The intent of the program was to decrease juvenile recidivism and increase substance abuse resistance. Programa Shortstop is a family based intervention designed for Hispanic youth ages 9–17. The intervention was delivered to 352 youth and at least one parent/caregiver over the 5-year study period. For intervention youth, the results of the recidivism study ( n = 321) indicated that 89% of youth participating in Programa Shortstop between 1995 to 1997 were not rearrested within one year of completing Programa Shortstop. Additionally, statistical paired t-test analysis found that the intervention model had a positive effect on legal knowledge and school related factors associated with substance abuse and delinquency. Parent participants demonstrated significant increases in knowledge related to substance abuse and the legal system.
Student Effort, Media Preference, and Writing Quality When Using Print and Electronic Resources in Expository Writing
Authors: Schuh Kathy L. , Farrell Courtney A.
Published: February 2007

The purpose of this study was to analyze the effects of the Internet as a research tool on elementary students' quality of writing, their perceptions of effort expended, and their resource media preference in writing an expository paper. We gathered data from 56 upper-elementary students as they wrote expository papers using print resources, electronic resources via the Internet, or both types of resources. We noted no significant differences among the quality of writing that could be attributed to the resources used or grade in school. However, students liked using the Internet more than traditional print resources for doing research. In addition, fifth-grade students perceived that they put forth more effort when using the Internet for this writing task.
Relationship of Self-Beliefs, Social Support, and University Comfort with the Academic Success of Freshman College Women
Authors: Rayle Andrea Dixon , Kurpius Sharon E. Robinson , Arredondo Patricia
Published: February 2007

The relationships of self-beliefs, social support, and university comfort with the academic persistence decisions and first-year grade point averages of 527 first semester female undergraduates were examined. Data were gathered in 56 classes or group meetings. These three constructs predicted academic persistence decisions, with social support as the strongest predictor, followed by self-beliefs, and then university comfort. Although there were no differences between Euro-American women and women of color on initial academic persistence decisions, Euro-American women had higher first-year GPAs than did the women of color. Research-informed practice and policy implications for increasing the persistence decisions and academic success of first-year female college students are discussed.
Effects of Nonverbal Problem Solving Treatment on Skills for Externalizing Visual Representation in Upper Elementary Grade Students with and without Dyslexia
Authors: Winn William , Berninger Virginia , Richards Todd , Aylward Elizabeth , Stock Pat , Lee Yen-Ling , Lovitt Dan
Published: February 2007

Two groups of twelve dyslexic children and twelve good readers attended a two-week class during the summer following their enrollment in grades 4–6. The topic was the marine environment and focused on the adventures of an orca whale that had lost its family and needed the children's help. The children attended class for three hours each day, 45 minutes of which were devoted to working with a computer-based, interactive, three-dimensional simulation of the ocean. The rest of the time was spent on hands-on, problem-based, non-verbal classroom activities. Data obtained from logs of the children's activity using the computer, maps drawn on two occasions from memory, and brain activation obtained from fMRI before and after the class showed that the dyslexic children were as able to use the simulation and construct spatial mental models as the good readers. However, significant correlations among activation of areas of the brain associated with working memory were found during fMRI imaging for good readers performing a 2-back visual memory task, but not for dyslexics. Significant correlations were also found among time taken for dyslexics, but not good readers, to complete computer-based exercises and activation of area V5 while they performed tasks requiring visual decoding of pseudowords. These findings, which suggest that good readers and dyslexics might use their brains differently to reach similar levels of performance, were interpreted within cognitive and neurocognitive theories of learning.
Representativity of the Midwestern Paleoindian Sample
Authors: Shott Michael J.
Published: February 2007

Knowing Midwestern Paleoindians from archaeological evidence requires due regard for the record's quality as a sample. How big is it? How much of it do we have? How representative is this sample by size and composition? Estimating Cowgill's “physical-finds population” partly from the existing sample, I gauge “representativity” of the Midwestern Paleoindian record. Yes, the sample is small and biased, but representativity is no counsel of despair that available evidence is hopelessly corrupted. Instead, it identifies better data-collection methods and is a necessary prelude to intelligent synthesis.
Mentoring and Retention in College Science: Reflections on the Sophomore Year
Authors: Packard Becky Wai-Ling
Published: February 2007

Although mentoring has been linked to the retention of college students in science, it is still unclear whether students who persist in science majors (pursuers) have greater mentoring experiences than students who do not persist (switchers). In this study, 79 upper-level students who had enrolled as science majors at a research university were surveyed about the science mentoring they experienced during their sophomore year, a time when students were asked to make final decisions about their major. Pursuers reported greater science career mentoring than switchers, but there were no differences for psychosocial mentoring. In addition, students perceived similar barriers to and need for science mentoring, but pursuers initiated science mentoring more than switchers. Implications for future mentoring initiatives are discussed.
Reaching the Underserved: Measuring the Impact of a Community Media Intervention, Uttar Pradesh, India
Authors: Sood Suruchi , Singh Pramod Kumar , Sarwal Rakesh
Published: February 2007

This article examines the impact of a community-based health promotion initiative implemented in the state of Uttar Pradesh in North India in measurably improving knowledge, interpersonal communication, and practices related to HIV/AIDS and STIs among rural audiences with low or no access to mass media. Using a panel study design and logistic regression analysis, results indicate that at endline the exposed panel of respondents report significantly higher levels of knowledge and interpersonal communication regarding HIV/AIDS and STIs in comparison to the reports from the same set of respondents at baseline and also the respondents not exposed at endline. Some control variables—such as gender, education, and media access—display some interaction effects with the dependent variables. The findings suggest that community-based media initiatives are a strong vehicle in promoting changes in knowledge and producing positive behavioral outcomes especially by reaching out to underserved communities that have relatively fewer alternative sources of information on sensitive sexual health issues.
The Relationship between Self-Report Imagery Questionnaire Scores and Sub-Types of Socially Desirable Responding: Components of Visual Imagery
Authors: Allbutt John , Ling Jonathan , Shafiullah Mohammed
Published: February 2007

Allbutt, Shafiullah, and Ling [1] found that scores on self-report measures of visual and movement imagery vividness correlate primarily with an egoistic form of socially desirable responding rather than a moralistic form. The current study investigated whether the pattern of findings generalizes to the ratings of other imagery properties such as the ease with which an image can be generated. Participants completed the Shapes Questionnaire [2] and the Balanced Inventory of Desirable Responding [3]. Several of the shapes Questionnaire ratings correlated significantly with the egoistic form of socially desirable responding, while correlations with the moralistic form were rare. This shows the pattern of findings generalizes to the ratings of properties of the imagery experience other than vividness.
Talbot bands and temporal processing of optical signals
Authors: Jahns J. , Lohmann A.W. , Bohling M.
Published: February 2007

Talbot’s bands can be observed in one of the diffraction orders of a grating spectrometer with a partially phase-shifted input beam. This experiment has long been considered as a curiosity. Here, we look at it from a new perspective: we discuss the Talbot band experiment as a combination of two kinds of dispersion, refractive and diffractive. This may be of interest for various tasks of temporal optical signal processing such as dispersion management and the shaping of ps/fs-pulses. For this purpose, we demonstrate the use of micro machined optical elements to alter the performance of the classical Talbot band setup. A theoretical description and experimental results are presented.
Joint probability distributions for optical parametric down-conversion
Authors: Peřina Jan , Křepelka Jaromír
Published: February 2007

We derive multi mode joint generating functions, photon-number distributions, integrated-intensity distributions and related quantities for spontaneous and stimulated parametric down-conversion in relation to experiments.
Generation of Squeezing in Higher Order Hermite-Gaussian Modes with an Optical Parametric Amplifier
Authors: Lassen M. , Delaubert V. , Harb C.C. , Lam P.K. , Treps N. , Bachor H-A.
Published: February 2007

We demonstrate quantum correlations in the transverse plane of continuous wave light beams by producing −4.0 dB, −2.6 dB and −1.5 dB of squeezing in the TEM00, TEM10 and TEM20 Hermite-Gauss modes with an optical parametric amplifier, respectively. This has potential applications in quantum information networking, enabling parallel quantum information processing. We describe the setup for the generation of squeezing and analyse the effects of various experimental issues such as mode overlap between pump and seed and nonlinear losses.
High-NA aberration retrieval with the Extended Nijboer-Zernike vector diffraction theory
Authors: van Haver S. , Braat J.J.M. , Dirksen P. , Janssen A.J.E.M.
Published: February 2007

The reconstruction of the exit pupil function of an optical system can basically be carried out by collecting intensity data in the focal region from a certain number of defocused image planes. In this paper we present the first results of such a reconstruction operation for optical systems with a high numerical aperture using a point source in the object plane. The main feature of our approach is the use of the extended Nijboer-Zernike diffraction analysis that has been modified to incorporate vector diffraction effects. The quality of the optical system is expressed by means of a set of complex Zernike coefficients that describe the phase and transmission variation in the exit pupil of the imaging system. The ’vector’ method will be compared to the more common scalar diffraction analysis. We also analyse the practical limits of the vector retrieval process regarding the maximum allowed aberration and the noise of the intensity data. The sensitivity of the method with respect to parameter settings (state of polarisation and value of numerical aperture) is also examined.
Coherence effects in propagation through photonic crystals
Authors: Mandatori A. , Bertolotti M. , Sibilia C. , Hoenders B.J. , Scalora M.
Published: February 2007

We have analytically studied how a partially coherent quasi plane wave is affected by a photonic crystal structure including a grating. The analysis is presented for spatial and temporal cases showing the possibility to determine the coherence characteristics of the pulse.
Electrically tunable, ultranarrowband, circular–polarization rejection filters with electro–optic structurally chiral materials
Authors: Lakhtakia Akhlesh
Published: February 2007

The transmittance spectrum of a slab of an electro–optic structurally chiral material (SCM) that is helicoidally non homogeneous in the thickness direction and is endowed with a central 90°–twist defect, shows evidence of an ultranarrowband spectral hole when a sufficiently high dc electric field is applied between the entry and the exit planes and the incident light is circularly polarized in opposition to the structural handedness of the SCM. This spectral hole migrates on the wavelength axis as the applied dc electric field is altered in magnitude, thereby suggesting the possible use of a centrally defective, electro–optic SCM slab as an electrically tunable, circular–polarization rejection filter with ultra narrow bandwidth.
Fabrication and Characterization of low-loss polymeric waveguides and micro-resonators
Authors: Scheuer Jacob , Yariv Amnon
Published: February 2007

We realize low loss, single-mode polymer waveguides and microring resonators in SU-8 (MichroChem) using direct E-beam lithography. We also present and demonstrate a novel and simple approach for accurately extracting the propagation loss in the waveguides as well as the coupling between the waveguide and the microring. The demonstrated approach is insensitive to the I/O coupling efficiency to the optical chip and does not require any pre-calibration of the experimental setup.
Illustrations of optical vortices in three dimensions
Authors: O’Holleran Kevin , Dennis Mark R. , Padgett Miles J.
Published: February 2007

Optical vortices (phase singularities) arise from interference and are threads of darkness embedded within light fields. Although usually visualised in terms of their points of intersection with an observation plane, appreciation of their true form requires a view in three dimensions. Through numerical simulation we re-examine three situations where optical vortex lines evolve as an additional parameter is varied. Our specific examples are: the addition of a fourth plane wave of varying amplitude into a superposition of three plane waves, the increase of height of a non-integer spiral phase step, and finally the perturbation that creates, and then dissolves, a vortex link in a specific combination of Laguerre-Gauss modes.
Photonic crystal fibres: mapping Maxwell’s equations onto a Schrödinger equation eigenvalue problem
Authors: Mortensen Niels Asger
Published: February 2007

We consider photonic crystal fibres (PCFs) made from arbitrary base materials and introduce a short-wavelength approximation which allows for a mapping of the Maxwell’s equations onto a dimensionless eigenvalue equations which has the form of the Schrödinger equation in quantum mechanics. The mapping allows for an entire analytical solution of the dispersion problem which is in qualitative agreement with plane-wave simulations of the Maxwell’s equations for large-mode area PCFs. We offer a new angle on the foundation of the endlessly single-mode property and show that PCFs are endlessly single mode for a normalized air-hole diameter smaller than ∼ 0.42, independently of the base material. Finally, we show how the group-velocity dispersion relates simply to the geometry of the photonic crystal cladding.
Invertebrate superposition eyes-structures that behave like metamaterial with negative refractive index
Authors: Stavenga D.G.
Published: February 2007

The superposition eyes of moths and lobsters are described with the geometrical optics for a refractive surface between two media, where the refractive index of the image space is negative. Consequently, the eye power and the object focal length are negative, whereas the image focal length is positive. The F-number is also negative, but the sign is irrelevant for calculations of the light sensitivity, because that depends on F2.
Efficient optimization of hollow-core photonic crystal fiber design using the finite-element method
Authors: Holzlöhner Ronald , Burger Sven , Roberts Peter J. , Pomplun Jan
Published: February 2007

We employ a finite-element (FE) solver with adaptive grid refinement to model hollow-core photonic crystal fibers (HC-PCFs) whose core is formed from 19 omitted cladding unit cells. We optimize the complete fiber geometry for minimal field intensity at material/air interfaces, which indicates low loss and high damage threshold, using multidimensional optimization. The optimal design shows a 99.8 % power fraction within the air and an overlap with a Gaussian mode of 96.9 %.
Compact supercontinuum source for the visible using gain-switched Ti:Sapphire laser as pump
Authors: Räikkönen E. , Kaivola M. , Buchter S. C.
Published: February 2007

We demonstrate the use of a miniature gain-switched Ti:Sapphire laser for efficient generation of visible supercontinuum light in a highly nonlinear microstructured optical fiber. This allows for a compact setup that puts out nanosecond pulses of light covering the spectral range from 410 to 1300 nm. The source offers a low-cost alternative to the mode-locked-laser-pumped systems in the generation of visible supercontinuum light.
Influence of the Raman depolarisation ratio on far-field radiation patterns in coherent anti-Stokes Raman scattering (CARS) microscopy
Authors: Gachet David , Sandeau Nicolas , Rigneault Hervé
Published: February 2007

We propose a full-vectorial numerical study of far-field radiation patterns in coherent anti-Stokes Raman scattering (CARS) microscopy. We emphasis the particular role of the Raman depolarisation ratio of the observed medium and show how it modifies the radiation pattern of thin objects.
Switching and instabilities of optical vortices in nonlinear dual-core photonic crystal fibre couplers
Authors: Salgueiro José R. , Michinel Humberto , Ferrando Albert , Kivshar Yuri S.
Published: February 2007

We study switching of an optical vortex launched into one core of a dual-core waveguide coupler in a photonic crystal fibre with self-focusing nonlinearity. We analyse how the beam power and the angular momentum associated with the vortex mode transfer to the second core of the coupler in both linear and nonlinear regimes. We describe three major scenarios of the vortex dynamics and reveal novel symmetry-breaking instabilities associated with the vortex nonzero angular momentum.
Effective spectral optical functions of lamellar nanogratings
Authors: Foldyna Martin , Postava Kamil , Ossikovski Razvigor , De Martino Antonello , Garcia-Caurel Enric
Published: February 2007

Spectral properties of lamellar sub-wavelength gratings (nanogratings) are described by effective medium approximation (EMA). Analytical spectral formulae for ordinary and extraordinary effective optical functions are derived for nanogratings consisting of material described by Sellmeier, damped harmonic oscillator, and Drude formulae. Spectral origin for birefringence of dielectric nanogratings and linear dichroism for absorbing ones is discussed for model cases and gratings consisting of real natural materials. Simple approximation by zero-order diffraction is compared with rigorous modeling based on Rigorous Coupled Wave Analysis (RCWA). Limits of applicability of effective medium approximation is discussed in the spectral domain.
Interference or not: analysis of Young’s experiment for a single-cycle pulse
Authors: Girieud G. , Pereira S. F.
Published: February 2007

An analysis of Young’s interference experiment for single cycle pulses showing the time evolution of the interference pattern due to two square apertures is obtained in the Fresnel regime. The fact that the diffraction pattern from each aperture is not constant in time has consequences on the interference pattern. We have also analyzed the changes in the spectrum at different regions at the observation plane. This position-dependent spectrum results in frequency beating of the interference pattern for the case of two apertures.
Transverse magneto-optical Kerr effect measured using phase modulation
Authors: Postava K. , Maziewski A. , Stupakiewicz A. , Wawro A. , Baczewski L. T. , Višňovský Š. , Yamaguchi T.
Published: February 2007

An ellipsometric configuration for measurement of the complex transverse magneto-optical Kerr effect is described that uses a photoelastic modulator (PEM). The real and imaginary parts of the complex transverse Kerr effect are represented as small perturbations of ellipsometric angles ψ and ∆. The measurement, based on null ellipsometry and zone averaging, gives high signal typical for modulation techniques and insensitivity to other magnetisation components and system imperfections. The method is demonstrated by the measurement of transverse component during magnetisation reversal in a thin cobalt film.
Temporal Lau effect: Noncoherent Regeneration of Periodic Pulse Trains
Authors: Lancis Jesús , Gómez-Sarabia Cristina M. , Ojeda-Castañeda Jorge , Fernández-Pousa Carlos R. , Andrés Pedro
Published: February 2007

We present an optical method for implementing the temporal Talbot effect with a spectrally incoherent optical source and a linear dispersive medium, at the first-order dispersion regime. We state the condition for achieving this effect, here denoted as the temporal Lau effect.
Mesoscopic magnetism in dielectric photonic crystal meta materials: topology and inhomogeneous broadening
Authors: Mortensen Niels Asger , Xiao Sanshui , Felbacq Didier
Published: February 2007

We consider meta materials made from a two-dimensional dielectric rod-type photonic crystal. The magnetic response is studied within the recently developed homogenization theory and we in particular study the effects of topology and inhomogeneous broadening. While topology itself mainly affects the Mie resonance frequency we find that the dispersion in the topological radius ℛ of the dielectric rods may lead to significant inhomogeneous broadening and suppression of the negative-µ phenomena for δℛ/ℛ0 ≫ ε″/ε′, with ε = ε′ + iε″ being the relative dielectric function of the rods.
Comparison of beam combiners for a synthetic aperture imaging telescope
Authors: van der Avoort Casper , Pereira Silvania F. , Braat Joseph J.M. , den Herder Jan-Willem
Published: February 2007

Future astronomical space missions will comprise a constellation of several optical telescopes to detect exo-planets by interferometric nulling of starlight. The Darwin mission of the European Space Agency (ESA) and NASAs Terrestrial Planet Finder Interferometer both consist of a free-flying collection of telescopes and a beam combiner. As such, the constellation provides a co-phased array of telescopes that can also be used for aperture synthesis imaging. This imaging technique relies on recording intensity interference patterns, in which the layout of the beam combination optics and the detector play a key role. Several designs for beam combination have been proposed in the literature. In this article, we compare these beam combiners by rigorously simulating the imaging process of a weak stellar source, taking into account the photon arrival statistics, an imperfect detection process and the image reconstruction from the recorded data. The results are presented as the to be expected reconstruction error in the luminous intensity distribution function of a wide-field stellar source versus the provided amount of photons. Using these results, the optimum design of the combination beam combiner and detector array can be identified.
Resonant second harmonic generation in random dielectric structures
Authors: Centini Marco , Felbacq Didier , Wiersma Diederick S. , Sibilia Concita , Scalora Michael , Bertolotti Mario
Published: February 2007

We show that resonant second harmonic generation can be obtained in random dielectric structures. The scheme is based on internal resonances due to the optical counterpart of Anderson localization. By making use of different localization lengths at the fundamental and at the second harmonic frequencies, we predict a conversion efficiency that is four orders of magnitude higher than a bulk material and even one order of magnitude higher than an ideal phase matched slab of the same size. The method is highly insensitive to fabrication tolerances, and provides excellent angle tunability.
Retroreflector array as a tapped delay-line filter for ultra-short optical pulses
Authors: Sabatyan A. , Jahns J.
Published: February 2007

A retroreflector array can be used to act as an optical tapped delay-line filter for temporal optical signals. Here, we demonstrate the basic operation and present a theoretical description. Our theory is based on the mathematical formalism for finite impulse response filters. A relationship to the classical Talbot bands experiment is established. By adding a mask to the retroreflector array, one can implement arbitrary filter operations. As a specific example, a differentiation in frequency domain is demonstrated by using a simple binary mask. The proposed devise maybe useful for the optical filtering and shaping of ultra short pulses.
Wide-band optical field concentrator for low-index core propagation
Authors: de Ceglia D. , De Sario M. , D’Orazio A. , Petruzzelli V. , Vincenti M.A. , Prudenzano F. , Scalora M.
Published: February 2007

We propose a novel chirped structure consisting of a low index polymer core bounded by modulated multilayer claddings, to realize an optical field concentrator with virtually zero propagation losses in a wide spectral range, independent of wave polarization. In spite of the absence of the total internal reflection mechanism, properly designed multilayer claddings ensure the achievement of unitary transmittance in a wide spectral range, including the widely used wavelengths for optical communications. Several cladding geometries obtained by varying the thicknesses of the cladding layers are reported and discussed.
Passive introduction of carrier fringes in real-time photo refractive interferometers for single interferogram analysis
Authors: Pauliat Gilles , Roosen Gérald , Georges Marc P. , Pedrini Giancarlo
Published: February 2007

We propose a new technique to introduce carrier fringes in an holographic interferometric set-up for deformation or vibration analyses. This technique makes use of the anisotropic diffraction processes of photorefractive crystals. The main advantage of the proposed technique is that it just involves static components, no moving parts or active components are required. This technique is demonstrated in a real-time interferometric set-up operating at the wavelength of 1.06 µm and with a GaAs photorefractive crystal as the holographic medium.
Laser Doppler imaging of microflow
Authors: Atlan M. , Gross M. , Leng J.
Published: February 2007

We report a pilot study with a wide-field laser Doppler detection scheme used to perform laser Doppler anemometry and imaging of particle-seeded microflow. The optical field carrying the local scatterers (particles) dynamic state, as a consequence of momentum transfer at each scattering event, is analyzed in the temporal frequencies domain. The setup is based on heterodyne digital holography, which is used to map the scattered field in the object plane at a tunable frequency with a multipixel detector. We show that wide-field heterodyne laser Doppler imaging can be used for quantitative microflow diagnosis; in the presented study, maps of the first-order moment of the Doppler frequency shift are used as a quantitative and directional estimator of the Doppler signature of particles velocity.
Highly dispersive photonic band-gap-edge optofluidic biosensors
Authors: Xiao Sanshui , Mortensen Niels Asger
Published: February 2007

Highly dispersive photonic band-gap-edge optofluidic biosensors are studied theoretically. We demonstrate that these structures are strongly sensitive to the refractive index of the liquid, which is used to tune dispersion of the photonic crystal. The upper frequency band-gap edge shifts about 1.8 nm for δn = 0.002, which is quite sensitive. Results from transmission spectra agree well with those obtained from the band structure theory.