bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequently asked questions about conscious will
Authors: Wegner Daniel M.
Published: April 2005

The commentators' responses to The Illusion of Conscious Will reveal a healthy range of opinions – pro, con, and occasionally stray. Common concerns and issues are summarized here in terms of 11 “frequently asked questions,” which often center on the theme of how the experience of conscious will supports the creation of the self as author of action.
A TWO-NODE JACKSON NETWORK WITH INFINITE SUPPLY OF WORK
Authors: Adan Ivo , Weiss Gideon
Published: April 2005

We consider a Jackson network with two nodes, with no exogenous input,
but instead an infinite supply of work at each of the nodes: Whenever a
node is empty, it processes a job from this infinite supply. We obtain an
explicit expression for the steady state distribution of this system, as
an infinite sum of product forms.
A NOTE ON GENERATING SYSTEMS COMPOSED OF BINARY AND TERNARY RANDOM
VARIABLES
Authors: Block Henry , Mazumdar Mainak , Ross Sheldon M.
Published: April 2005

We present some tips for generating multiple sequences of two- and
three-valued random variables.
NEW ESTIMATORS FOR EFFICIENT GI/G/1
SIMULATION
Authors: Wang Chia-Li , Wolff Ronald W.
Published: April 2005

For simulating GI/G/1 queues, we investigate
estimators of stationary delay-in-queue moments that were suggested but
not investigated in our recent article and we develop new ones that are
even more efficient. Among them are direct spread estimators that
are functions of a generated sequence of spread idle periods and are
combinations of estimators. We also develop corresponding
conditional estimators of equilibrium idle-period moments and
delay moments. We show that conditional estimators are the most efficient;
in fact, for Poisson arrivals, they are exact. In simulation runs with
both Erlang and hyperexponential arrivals, conditional estimators of mean
delay are more efficient than a published method that estimates
idle-period moments by factors well over 100 and by factors of over 800 to
several thousand for estimating stationary delay variance.
ON AN EQUIVALENCE BETWEEN LOSS RATES AND CYCLE MAXIMA IN QUEUES AND
DAMS
Authors: Bekker René , Zwart Bert
Published: April 2005

We consider the loss probability of a customer in a single-server
queue with finite buffer and partial rejection and show that it can be
identified with the tail distribution of the cycle maximum of the
associated infinite-buffer queue. This equivalence is shown to hold for
the GI/G/1 queue and for dams with
state-dependent release rates. To prove this equivalence, we use a duality
for stochastically monotone recursions, developed by Asmussen and Sigman
(1996). As an application, we obtain several exact and asymptotic results
for the loss probability and extend Takács' formula for the
cycle maximum in the M/G/1 queue to dams with
variable release rate.
Funkify and Diversify or The Politics of Dancing—Reflections
on APSA in Chicago
Authors: Webb Ed
Published: April 2005

“If I can't dance, I don't want to come to your revolution”—Emma Goldman
APSA Task Force on Graduate Education: 2004 Report to the
Council
Authors: Beltran Cristina , Cohen Cathy J. , Collier David , Goldenberg Edie , Keohane Robert , Monroe Kristen , Wallerstein Michael , Achen Christopher H. , Smith Rogers M.
Published: April 2005

In spring 2002, APSA President-Elect Theda Skocpol appointed this Task Force on Graduate
Education, representing a variety of institutions, political science subfields, scholarly
backgrounds, and methodological viewpoints. She asked its members to report on ways to
strengthen graduate education in political science. The Task Force quickly concluded that no
single structure of graduate training could be appropriate for the wide range of
institutions offering graduate instruction in political science, and that departments must
decide for themselves what programs best suited their capacities and interests.
A Scanning Electron and Atomic Force Microscopy Study of the
Surface Morphology and Composition of CsI Films as Affected by
Evaporation Rate and Humid-Air Exposure
Authors: Senesi Giorgio S. , Nitti Mariangela A. , Valentini Antonio
Published: April 2005

Evaporation rate and subsequent exposure to humid air affect the
surface morphology and composition of cesium iodide (CsI) films and, in
turn, their photoemissive efficiency when used as photocathodes. The
surface morphology and elemental composition of 300-nm-thick CsI films
grown at two different rates (1 nm/s and 0.04 nm/s), both
freshly evaporated and after 24-h exposure to humid air were
investigated by means of atomic force microscopy and scanning electron
microscopy/electron diffraction spectroscopy. The CsI film freshly
evaporated at a slow rate exhibited a granular surface presenting
circular holes or craters where the CsI material was moved from the
center to the boundaries. After 24-h exposure to humid air, this film
coalesced in large grain showing a marked increase of surface
roughness. Conversely, the CsI film grown at a fast rate mostly
retained its original surface uniformity and homogeneity with no
presence of holes and craters after 24-h exposure to humid air.
Further, surface roughness and average peak height decreased, but the
surface coalesced in large grains spaced by small fractures where the
CsI coverage was almost lost. In conclusion, the films grown at a fast
evaporation rate were affected by 24-h exposure to humid air less than
those grown at a slow rate, and are thus expected to possess a greater
long-term stability.
Transmission Electron Microscopy and X-Ray Diffraction Analysis of Aluminum-Induced Crystallization of Amorphous Silicon in α-Si:H/Al and Al/α-Si:H Structures
Authors: Kishore Ram , Hotz C. , Naseem H.A. , Brown W.D.
Published: April 2005

Solid phase crystallization of plasma-enhanced chemical-vapor-deposited (PECVD) amorphous silicon (α-Si:H) in α-Si:H/Al and Al/α-Si:H structures has been investigated using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Radiative heating has been used to anneal films deposited on carbon-coated nickel (Ni) grids at temperatures between 200 and 400°C for TEM studies. α-Si:H films were deposited on c-Si substrates using high vacuum (HV) PECVD for the XRD studies. TEM studies show that crystallization of α-Si:H occurs at 200°C when Al film is deposited on top of the α-Si:H film. Similar behavior was observed in the XRD studies. In the case of α-Si:H deposited on top of Al films, the crystallization could not be observed at 400°C by TEM and even up to 500°C as seen by XRD.
Letter to the Editor: Limitations to the Measurement of Oxygen Concentrations by HRTEM Imposed by Surface Roughness
Authors: Lupini Andrew R. , Chisholm Matthew F. , van Benthem Klaus , Allen Leslie J. , Oxley Mark P. , Findlay Scott D. , Varela Maria , Pennycook Stephen J.
Published: April 2005

In an article published inMicroscopy and Microanalysisrecently (Jia et al., 2004), it was claimed that aberration-corrected high resolution transmission electron microscopy (HRTEM) allows the quantitative measurement of oxygen concentrations in ceramic materials with atomic resolution. Similar claims have recently appeared elsewhere, based on images obtained through aberration correction (Jia et al., 2003; Jia & Urban, 2004) or very high voltages (Zhang et al., 2003). Seeing oxygen columns is a significant achievement of great importance (Spence, 2003) that will doubtlessly allow some exciting new science; however, other models could provide a better explanation for some of the experimental data than variations in the oxygen concentration. Quantification of the oxygen concentrations was attempted by comparing experimental images with simulations in which the fractional occupancy in individual oxygen columns was reduced. The results were interpreted as representing nonstoichiometry within the bulk and at grain boundaries. This is plausible because previous studies have shown that grain boundaries can be nonstoichiometric (Kim et al., 2001), and it is indeed possible that oxygen vacancies are present at boundaries or in the bulk.However, is this the only possible interpretation?We show that for the thicknesses considered a better match to the images is obtained using a simple model of surface damage in which atoms are removed from the surface, which would usually be interpreted as surface damage or local thickness variation (from ion milling, for example).
Evolution of PBL from normal epithelium to DCIS
Authors: Mohsin S. K. , Allred D. C.
Published: April 2005

A large number of studies in the last three decades have identified only a handful of biological features in the evolution of human premalignant breast lesions (PBL). They have shown that PBL have a positive growth balance, which may be driven/regulated by oestrogen receptor, erbB-2, and p53. There is marked genetic diversity in PBL, and use of newer technologies such as SAGE, DNA microarrays, and high-throughput proteomics will significantly improve our understanding of evolution of PBL over the next decade.
The role of aromatase inhibitors as adjuvant therapy in early breast cancer
Authors: Buzdar A. U.
Published: April 2005

Endocrine therapy is now established as the treatment option of choice for postmenopausal women with hormone receptor-positive advanced breast cancer. The benefit of the third-generation aromatase inhibitors (AIs) in this setting has prompted their evaluation in the treatment of early breast cancer. This article reviews the current clinical status of AIs as adjuvant therapy for early-stage breast cancer in postmenopausal women, focusing on the largest adjuvant breast cancer study till date to provide data, the ‘Arimidex’, Tamoxifen, Alone or in Combination (ATAC) trial.
Mammary stem cells: the root of breast cancer?
Authors: Coppock H. A. , Clarke R. B.
Published: April 2005

Tissue-specific stem cells play a key role in organ homoeostasis. They are relatively well characterized in systems which undergo constant proliferation and production of differentiated cells, including the haemopoietic system, skin and intestine. However, little is known about the role and regulation of stem cells in the mammary gland. This review briefly summarizes the current understanding of the role of breast-specific stem cells in normal and cancerous tissues, and how this may identify new targets for breast cancer prevention and therapy.
MRI in familial breast cancer
Authors: Gilhuijs K. G. A. , Deurloo E. E.
Published: April 2005

Five to ten per cent of all breast cancers are associated with a proven genetic predisposition for the disease or a strong family history of breast cancer in which yet unknown genetic predisposition is suspected. Carriers of germline mutations in genes breast cancer 1 or 2 (BRCA1/2) have up to 85% chance of developing breast cancer during their lifetime. The majority of these women develop the disease before the age of 50 years. Consequently, breast-cancer screening programmes aimed at reducing mortality in this population may only be effective if they start at much younger age than the general breast-cancer screening programmes. Unfortunately, the efficacy of conventional X-ray mammography in premenopausal women is often limited by dense fibroglandular tissue that obscures suspicious lesions. As a result, more advanced breast-imaging techniques have been considered, such as contrast-enhanced (CE) magnetic resonance imaging (MRI). In symptomatic patients, the sensitivity of CE MRI to detect invasive breast cancer is known to be high, regardless of the density of the fibroglandular tissue. Conversely, the specificity of CE MRI to discriminate between benign and malignant lesions is variable, and depends on the indication of the examination. Low specificity could result in many recalls on benign lesions, thus negatively affecting the cost–benefit ratio of CE MRI as a screening technique. Several single- and multi-institutional studies have been performed to investigate the efficacy of CE MRI as a screening tool exclusively for asymptomatic women at increased lifetime risk of breast cancer. Mounting evidence suggests that the addition of CE MRI results in cost-effective detection of tumours at earlier stage in BRCA1/2 mutation carriers. The value of CE MRI in other populations at risk is currently uncertain, and it is unlikely that CE MRI will be cost efficient in the general screening population of women who are not at increased lifetime risk.
Ductal carcinoma in situ of the breast – an overview of the randomized clinical trials
Authors: Meijnen Ph. , Rutgers E. J. Th.
Published: April 2005

Since 1985, 5411 patients were randomized in four large randomized clinical trials assessing the role of adjuvant radiotherapy and/or tamoxifen in breast conserving surgery for patients with ductal carcinoma in situ (DCIS).

First the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-17 trial proved relevance of postoperative radiotherapy in breast conserving surgery in DCIS patients: an approximately 50% reduction of ipsilateral tumour recurrences. This is confirmed by longer time of follow-up and validated by data from the European Organization for Research and Treatment of Cancer (EORTC) 10853 and UK Coordinating Committee on Cancer Research (UKCCCR) DCIS trials. A subset of patients who do not benefit of adjuvant radiotherapy cannot be identified. Completeness of excision proved to be the most important treatment variable to reduce local recurrence.

Both the NSABP B-24 and UKCCCR DCIS trials investigated the effect of tamoxifen resulting in contradictory findings. In addition a possible benefit seems to be restricted to oestrogen receptor-positive DCIS lesions nourishing the existent reserve in prescribing tamoxifen for all patients with DCIS.

The failure to materialize a difference in survival by the effect of either adjuvant radiotherapy or tamoxifen endorses the favourable outcome of DCIS. Currently, four other randomized clinical trials investigate the role of radiotherapy, tamoxifen, anastrazole, or no further treatment for a selected group of patients.
Regulation of E-cadherin
Authors: Yang Z. , Zhang H. , Kumar R.
Published: April 2005

Numerous studies suggest that loss of E-cadherin is necessary to induce Epithelial–mesenchymal transition (EMT) and metastasis. Snail is a major contributor to EMTs. The Snail family of zinc-finger transcription factors interact with the E-cadherin promoter to repress transcription during EMT. The present article reviews the regulation of E-cadherin and discusses recent novel insights into the molecular basis in the process of EMT.
Inhibition of estrogen receptor signaling
Authors: Rosen E. M. , Fan S.
Published: April 2005

The estrogen receptor-alpha (ER-α) is a Type I nuclear receptor that is over-expressed in the majority of human breast cancers and plays a significant role in the development and progression of these cancers. As estrogen plays important roles in the etiology of breast cancer and the growth of established ER-α expressing cancers, intense interest has been generated in understanding the mechanisms by which ER-α signaling is regulated physiologically and using this knowledge to develop interventions to inhibit ER-α signaling. These efforts have met with some success in the development of pharmacologic agents that can reduce breast cancer risk, prevent recurrence of established cancers, and treat advanced cancers with considerably less side effects than cytotoxic chemotherapy. Here, we will review some of the mechanisms that operate to inhibit ER-α signaling and describe how pharmacologic agents and dietary factors interact with ER-α to block its activity. In the process of reviewing these mechanisms, we will highlight their clinical implications.
Editorial
Authors: Miskin Christine
Published: April 2005

There are three main themes in this, the first issue of LIM for 2005. We begin with a series of short articles on the perils, pitfalls and challenges of multi-site working within the legal information environment. I am very grateful to the large number of people who have contributed to this theme by answering a short questionnaire that we put together in an attempt to ascertain what the key issues are. Some of our contributors have elected to answer the questions given as a template and others have adopted a more narrative style. Unfortunately we did not manage to get a contribution from an academic library. We do have articles from a number of our well-known large regional/City law firms, plus contributions from two smaller Scottish firms and the experiences of the College of Law. As a precursor to this theme our topical issues section features an article by Elisabeth Tooms, until recently Global Head of Library Services at Allen & Overy, on the challenges involved in running what must be the ultimate multi-site library with a staff of over 70 information professionals scattered around the world. Elisabeth also traces the history of her involvement in the development of the service from its beginnings in the early 1980's. At the other end of the spectrum Isabel Hood has written a wonderfully down-to-earth account of the stresses and strains of being a one-person library and information service in a multi-site law firm.
Mental health status of clients from three HIV/AIDS palliative care projects
Authors: KARUS DANIEL , RAVEIS VICTORIA H. , MARCONI KATHERINE , SELWYN PETER , ALEXANDER CARLA , HANNA BARBARA , HIGGINSON IRENE J.
Published: April 2005

Objective:To describe mental health status and its correlates among clients of three palliative care programs targeting underserved populations.

Methods:Mental Health Inventory (MHI-5) scores of clients from programs in Alabama (n= 39), Baltimore (n= 57), and New York City (n= 84) were compared.

Results:Mean MHI-5 scores did not differ among sites and were indicative of poor mental health. Significant differences were noted among sites with regard to client sociodemographics, physical functioning, and perceptions of interpersonal relations. Results of multivariate regression models estimated for each site suggest variation in the relative importance of potential predictors among sites. Whereas poorer mental health was primarily associated with history of drug dependence at Baltimore and more physical symptomatology at New York, better mental health was most strongly correlated with more positive perceptions of interpersonal relationships at Baltimore and increasing age and more positive perceptions of meaning and purpose in life at New York.

Significance of results:The data presented suggest the importance of assessing clients' history of and current need for mental health services. Evidence of a relationship between positive perceptions of meaning and purpose and better psychological function underscores the importance of existential issues for the overall well-being of those who are seriously ill.
Humor and laughter in palliative care: An ethnographic
investigation
Authors: DEAN RUTH ANNE KINSMAN , GREGORY DAVID M.
Published: April 2005

Objective: Humor and laughter are present in most of human
interaction. Interactions in health care settings are no exception.
Palliative care practitioners know from experience that humor and laughter
are common in palliative care despite the seriousness of the care context.
Research establishing the significance of humor in care of the dying is
limited.

Methods: Clinical ethnography conducted in a 30-bed inpatient
palliative care unit served as the means of exploring the functions of
humor in care of the dying. Clinical ethnography is intended for
examination of the human experience of illness or of caregiving in an
interpersonal context (Kleinman, 1992). The
method emphasizes the subjective experience and the realm of communication
and interaction for both patients and caregivers. Data were collected
through participant observation, informal interviews with patients and
families, and semistructured interviews with members of the health care
team.

Results: Humor and laughter were widespread and important in
the research setting. An overall attitude of good humor prevailed. Within
that atmosphere, humor served myriad functions. Functions were identified
in three overarching themes; building relationships, contending with
circumstances, and expressing sensibility. Humor among patients, families,
and staff most commonly served to build therapeutic relationships, relieve
tension, and protect dignity and a sense of worth. Humor was particularly
significant in maintaining collegial relationships, managing stressful
situations, and maintaining a sense of perspective.

Significance of results: Findings established the
significance of humor and laughter as humanizing dimensions of care of the
dying and contributes to the volume of research supporting evidence-based
practice.
Issues in psychotherapy with terminally ill patients
Authors: COHEN S. TZIPORAH , BLOCK SUSAN
Published: April 2005

Psychotherapy with the terminally ill poses special challenges for clinicians and in return offers unique rewards. As a time limited therapy, acceptance, rather than change is a primary goal; yet, patients can be strongly motivated to change. Patients may need to struggle with how to disengage while also maintaining connection. Unique transference and countertransference issues arise. The psychological tasks of dying include grieving, saying goodbye, constructing a meaningful context to one's life, and letting go. The therapist can serve as a companion and guide to the dying person as she or he negotiates these tasks. Through the use of a case example, these issues are explored from the perspectives of patient and therapist. The therapist must address the following issues: attending to physical suffering, differentiating between grieving and depression, addressing fears, facilitating the life review, and assisting in decision making. A dying patient's need to leave a legacy, complete relationships, grapple with spiritual and religious issues, and attend to his or her family, are often important themes. Therapists must work productively with denial, maintain flexible yet appropriate boundaries, grapple with their own anxiety about death, and grieve the loss of their patients. Psychotherapy with dying patients can help reduce their psychological pain, relieving psychosocial distress and providing opportunities for personal growth in the last stage of life. Such work is often draining yet immensely rewarding for the patient and therapist alike.
Mythen und Paradoxien der klassischen Testtheorie (II)
Authors: Yousfi Safir
Published: April 2005

Zusammenfassung. Aus der klassischen Testtheorie wird meist die Empfehlung abgeleitet, Tests aus möglichst trennscharfen Items zusammenzustellen. Die vorliegende Arbeit untersucht anhand mathematischer Formeln, in welchem Zusammenhang die Trennschärfe mit der Reliabilität und Validität von Items und Testwerten steht. Es zeigt sich, dass die Trennschärfe bei essenziell τ-äquivalenten und τ-kongenerischen Items ein sehr guter Indikator für die Reliabilität und Validität eines Items ist. Wenn die Korrelation der wahren Werte der Items gleich eins ist (τ-Kongenerität), wirkt sich die Itemselektion anhand der Trennschärfe in der Regel auch günstig auf die Gütekriterien des Tests aus. Auch bei unbekannter Beziehung zwischen den wahren Werten der Items eines Tests ist die Trennschärfe als Selektionskriterium durchaus geeignet, die Reliabilität eines Tests zu sichern. Besonders bei wenig reliablen Tests mit hoher Validität ist die Trennschärfe ebenfalls ein guter Indikator der Itemvalidität. Dennoch kann die Selektion von Items anhand der Trennschärfe im Allgemeinen keinen nennenswerten Beitrag zur Sicherung der Testvalidität leisten. Bei bekannter Itemvalidität wirkt sich ein Item umso günstiger auf die Validität des Tests aus, je geringer dessen Trennschärfe ist. Auch bei unbekannter Itemvalidität lassen sich durch die Trennschärfe allenfalls bei wenig reliablen, aber dennoch validen Tests solche Items identifizieren, die einen bedeutenden Einfluss auf die Validität haben. Bei unbekannter Beziehung zwischen den wahren Werten der Items sollte man bei der Testkonstruktion daher auf die Trennschärfe als Selektionskriterium eher verzichten und statt dessen andere Indikatoren der Itemvalidität verstärkt zu Rate zu ziehen.
Entwicklungsschritte für einen computeradaptiven Test zur Erfassung von Angst (A-CAT1)
Authors: Walter Otto B. , Becker Janine , Fliege Herbert , Bjorner Jakob , Kosinski Mark , Walter Marc , Klapp Burghard F. , Rose Matthias
Published: April 2005

Zusammenfassung. Die empirische Erfassung psychischer Merkmale erfolgt in der Regel mit Instrumenten, die auf der Grundlage der klassischen Testtheorie entwickelt wurden. Seit den 60er Jahren bietet sich hierzu mit der Item Response Theory (IRT) eine Alternative an, die verschiedene Vorteile verspricht. Auf ihrer Grundlage können u.a. computeradaptive Tests (CATs) entwickelt werden, welche die Auswahl der vorgelegten Items dem Antwortverhalten der Patienten anpassen und damit eine höhere Messgenauigkeit bei reduzierter Itemzahl ermöglichen sollen. Wir haben verschiedene Schritte zur Entwicklung eines CAT zur Erfassung von Angst unternommen, um zu prüfen, ob sich die theoretischen Vorzüge der IRT auch in der praktischen Umsetzung bestätigen lassen. In dem vorliegenden Beitrag wird die Entwicklung der zu Grunde liegenden Itembank dargestellt. Hierfür wurde auf Daten von N = 2348 Patienten zurückgegriffen, die an der Medizinischen Klinik mit Schwerpunkt Psychosomatik der Charité zwischen 1995 und 2001 im Rahmen der Routinediagnostik ein umfangreiches Set etablierter konventioneller Fragebögen computergestützt beantwortet hatten. Diese beinhalteten 81 Items, die in einem Expertenrating für das Merkmal Angst als relevant angesehen wurden. Die Eigenschaften dieser Items wurden anhand ihrer residualen Korrelationen nach konfirmatorischer Faktorenanalyse (MplusTM), ihrer Antwortkategorienfunktion (TestgrafTM) und ihrer Diskriminationsfähigkeit (ParscaleTM) überprüft. Es verblieben 50 Items, die für die Anwendung eines polytomen Zwei-Parameter-Modells (Generalized-Partial-Credit-Model) als geeignet angesehen werden können. Orientiert man sich an einer Reliabilität von ρ ≥ .90 und legt für den computeradaptiven Testalgorithmus einen Standardfehler von ≤ .32 fest, so zeigen Simulationsstudien, dass die Merkmalsausprägung für Angst im Bereich von ± 2 Standardabweichungen um den Mittelwert der Stichprobe mit ca. 7 Items ermittelt werden kann. Zudem legen die Simulationsstudien nahe, dass der CAT-Algorithmus das Merkmal in den oberen und unteren Ausprägungen besser zu differenzieren vermag als die konventionell berechnete Summen-Skala des STAI (State).
Comparison of coincident Multiangle Imaging Spectroradiometer and Moderate Resolution Imaging Spectroradiometer aerosol optical depths over land and ocean scenes containing Aerosol Robotic Network sites
Authors: Abdou Wedad A. , Diner David J. , Martonchik John V. , Bruegge Carol J. , Kahn Ralph A. , Gaitley Barbara J. , Crean Kathleen A. , Remer Lorraine A. , Holben Brent
Published: April 2005

The Multiangle Imaging Spectroradiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS), launched on 18 December 1999 aboard the Terra spacecraft, are making global observations of top‐of‐atmosphere (TOA) radiances. Aerosol optical depths and particle properties are independently retrieved from these radiances using methodologies and algorithms that make use of the instruments' corresponding designs. This paper compares instantaneous optical depths retrieved from simultaneous and collocated radiances measured by the two instruments at locations containing sites within the Aerosol Robotic Network (AERONET). A set of 318 MISR and MODIS images, obtained during the months of March, June, and September 2002 at 62 AERONET sites, were used in this study. The results show that over land, MODIS aerosol optical depths at 470 and 660 nm are larger than those retrieved from MISR by about 35% and 10% on average, respectively, when all land surface types are included in the regression. The differences decrease when coastal and desert areas are excluded. For optical depths retrieved over ocean, MISR is on average about 0.1 and 0.05 higher than MODIS in the 470 and 660 nm bands, respectively. Part of this difference is due to radiometric calibration and is reduced to about 0.01 and 0.03 when recently derived band‐to‐band adjustments in the MISR radiometry are incorporated. Comparisons with AERONET data show similar patterns.
Labrador Sea Water property variations in the northeastern Atlantic Ocean
Authors: Johnson Gregory C. , Bullister John L. , Gruber Nicolas
Published: April 2005

Labrador Sea Water (LSW) property variations are analyzed using data from four hydrographic sections occupied along 20°W, from Iceland south toward the equator in 1988, 1993, 1998, and 2003. LSW between the Azores‐Biscay Rise and the Rockall Plateau steadily becomes deeper, colder, fresher, denser, and thicker over the 15‐year time series. LSW apparent oxygen utilization (AOU) remains unchanged during this time period. The changes analyzed are consistent with previously published spreading rates of 8 years for LSW from the Labrador Sea to 20°W, and emphasize the long reach of decadal LSW variability.
Spectrometric and morphological characterization of condensed phase zirconium species produced during electrothermal heating on a graphite platform
Authors: Castro M. A. , Aller A. J. , McCabe A. , Smith W. E. , Littlejohn D.
Published: April 2005

The characterization of condensed phase zirconium species on a graphite platform was accomplished over the temperature range 200–2500 °C using surface analysis techniques. This resulting information will be of relevance for mechanistic studies using zirconium as a chemical modifier.
Visualizing and Discovering Non-Trivial Patterns in Large Time Series Databases
Authors: Lin Jessica , Keogh Eamonn , Lonardi Stefano
Published: April 2005

Data visualization techniques are very important for data analysis, since the human eye has been frequently advocated as the ultimate data-mining tool. However, there has been surprisingly little work on visualizing massive time series data sets. To this end, we developed VizTree, a time series pattern discovery and visualization system based on augmenting suffix trees. VizTree visually summarizes both the global and local structures of time series data at the same time. In addition, it provides novel interactive solutions to many pattern discovery problems, including the discovery of frequently occurring patterns (motif discovery), surprising patterns (anomaly detection), and query by content. VizTree works by transforming the time series into a symbolic representation, and encoding the data in a modified suffix tree in which the frequency and other properties of patterns are mapped onto colors and other visual properties. We demonstrate the utility of our system by comparing it with state-of-the-art batch algorithms on several real and synthetic data sets. Based on the tree structure, we further device a coefficient which measures the dissimilarity between any two time series. This coefficient is shown to be competitive with the well-known Euclidean distance.
High-resolution x-ray diffraction analysis of epitaxially grown indium phosphide nanowires
Authors: Kawamura T. , Bhunia S. , Watanabe Y. , Fujikawa S. , Matsui J. , Kagoshima Y. , Tsusaka Y.
Published: April 2005

Indium phosphide (InP) nanowires epitaxially grown on InP (111)B were investigated by using grazing incidence x-ray diffraction. A broad scattering at the tail of InP (22¯0) diffraction and an additional peak at the low angle side were observed, showing the formation of nanowires and alloys of the gold catalysts and indium. Scattering intensity along the [11¯0] direction was compared with calculations based on a cylinder model. The best fit was obtained for a 5.5-nm radius with a 2.5-nm deviation, which was smaller than the values determined from the secondary electron microscopy and photoluminescence spectroscopy measurements. This result is explained by an oxide layer on the nanowire sidewalls and the low quantum efficiency of photoluminescence yields for small nanowires since x-ray diffraction directly detects crystalline structure of nanowires.
Bulk growth of high-purity 6H-SiC single crystals by halide chemical-vapor deposition
Authors: Chung H. J. , Polyakov A. Y. , Huh S. W. , Nigam S. , Skowronski M. , Fanton M. A. , Weiland B. E. , Snyder D. W.
Published: April 2005

High-purity 6H-SiC single crystals were grown by the halide chemical-vapor deposition process. Growth was performed in a vertical hot-wall reactor with a separate injection of a silicon precursor (silicon tetrachloride) and a carbon precursor (propane). Typical growth rates were between 100 and 300μm∕h. The crystals contain very low concentrations of residual impurities. The main contaminants, namely, nitrogen and boron, are in the 1014atomscm−3 range. Crystals grown under Si-rich conditions were n type with low room temperature electron concentrations in the 1014–1015atomscm3 range and with room-temperature electron mobilities approaching 400cm2∕Vs. The resistivity of the material increased up to 1010Ωcm with increasing C∕Si ratio. Deep levels spectra show that the electron traps density decreases with increasing C∕Si ratio.
Conjectured orbital ordering behavior of Nd0.5Sr0.5MnO3 under high pressures
Authors: Yu R. C. , Tang J. , Yao L. D. , Matsushita A. , Yu Y. , Li F. Y. , Jin C. Q.
Published: April 2005

We have synthesized Nd0.5Sr0.5MnO3 polycrystalline bulk samples by solid state reaction, which show ferromagnetic (FM), A-type antiferromagnetic (AF) and charge ordering charge exchange (CE)-type AF transitions on cooling from room temperature to 78K. We consider that the abundant magnetic structures are caused by phase segregation. We have investigated and conjectured the orbital ordering behavior under hydrostatic pressures up to 7.5GPa and found that low pressure favors the A-type AF phase with d(x2−y2) orbital ordering and the CE-type AF phase with d(3x2−r2)∕d(3y2−r2) orbital ordering, while suppressing the FM phase with disordered orbital ordering; however, high pressure favors the A-type phase and suppresses the CE-type AF phase. Transport property enhancement and large resistance changes under high pressures are observed.
Epitaxial growth and properties of MoOx(2<x<2.75) films
Authors: Bhosle V. , Tiwari A. , Narayan J.
Published: April 2005

We report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscopy (XPS). Electrical resistivity and optical properties were investigated using four-point-probe resistivity measurements and spectroscopy techniques, respectively. It was found that the film had a monoclinic structure based on MoO2 phase and showed an unusual combination of high conductivity and high transmittance in the visible region after annealing. The unusual combination of these properties was realized by systematically controlling the relative fraction of different oxidation states of molybdenum, namely Mo4+, Mo5+, and Mo6+ in the monoclinic phase. For a film 60nm thick and annealed at 250°C for 1h, the ratio of Mo6+∕(Mo4++Mo5+) was determined to be ∼2.9∕1 using XPS, and a typical value of transmittance was ∼65% and resistivity close to 1×10−3Ωcm. These results demonstrate growth of epitaxial MoOx films with tunable electrical and optical properties. Further optimization of these properties is expected to result in applications related to display panels, solar cells, chromogenic (photochromic, electrochromic, gasochromic) devices, and transparent conducting oxides. Our ability to grow epitaxial MoOx films can further aid their integration with optoelectronic and photonic devices.
Grain-boundary magnetoresistance up to 42 T in cold-pressed Fe3O4 nanopowders
Authors: Serrate D. , De Teresa J. M. , Algarabel P. A. , Fernández-Pacheco R. , Galibert J. , Ibarra M. R.
Published: April 2005

The magnetoresistance (MR) in cold-pressed magnetite nanopowders has been studied using pulsed magnetic field up to 42 T and steady field up to 12 T. Ball milling in air produces pure and stoichiometric Fe3O4 grains of nanometric size coated by a thin layer of Fe2O3, which electrically isolates the magnetite and acts as a tunnel barrier. Therefore, the intergrain magnetoresistance of magnetite grain boundaries can be analyzed regardless of the bulk transport properties. At high fields and high temperature, the MR depends linearly on the field, whereas at lower fields a direct tunneling contribution governed by the surface magnetization appears. Below the Verwey transition (T<120K) the linear high-field MR disappears. We interpret these results in terms of the grain-boundary properties.
ac aging and space-charge characteristics in low-density polyethylene polymeric insulation
Authors: Chen G. , Fu M. , Liu X. Z. , Zhong L. S.
Published: April 2005

In the present work efforts have been made to investigate the influence of ac aging on space-charge dynamics in low-density polyethylene (LDPE). LDPE films with 200 μm were aged under various electric stress levels at 50 Hz for various times at ambient temperature. Space-charge dynamics in the samples after aging were monitored using the pulsed electroacoustic technique. It has been revealed that the space charge under ac aging conditions is related to the level of the applied field, duration of the voltage application, as well as the electrode materials. By comparing with the results of unaged sample the results from aged sample provide a direct evidence of changing trapping characteristics after ac aging. Negative space charge is present in the bulk of the material and the total amount of charge increases with the aging time. The amount of charge increases with the applied field. Charge decay test indicates that the charges are captured in deep traps. These deep traps are believed to form during the aging and related to change caused by injected charge. By using different electrode materials such as gold, brass alloy, and polyethylene loaded with carbon black, it was found that the electrode has an important role in the formation of charge, hence subsequent changes caused by charge. The charge dynamics of the aged samples under dc bias differ from the sample without ac aging, indicating changes brought in by ac aging. Chemical analysis by Fourier transform infrared spectroscope and Raman microscope reveals no detectable chemical changes taken place in the bulk of the material after ac aging. Finally, the consequence of the accumulation of space charge under ac conditions on the lifetime of the material has been discussed. The presence of deeply trapped space charge leads to an electric stress enhancement which may shorten the lifetime of the insulation system.
On unitary, irreducible representations of the proper, orthochronous Lorentz group
Authors: Kubieniec J.
Published: April 2005

The theory of unitary, irreducible representations of the proper, orthochronous Lorentz group is presented by means of the usual tensor calculus in Minkowski space–time. This makes all steps manifestly Lorentz invariant. Explicit expressions for spherically symmetric eigenfunctions of the first Casimir operator C1 of the proper, orthochronous Lorentz group are calculated and their completeness is proved.
Memory effect in smectic-A phase of ferroelectric liquid crystal
Authors: Thakur Anil K. , Bawa Sukhwant S. , Biradar Ashok M. , Kaur Sarabjot , Annapoorni S.
Published: April 2005

Memory effect has been observed in smectic-A (Sm-A) phase of ferroelectric liquid crystals (FLCs) using dielectric spectroscopy and texture observation. The dielectric relaxation processes in FLC materials with wide range of Sm-A phase and a high electroclinic coefficient have been investigated near the phase transition of Sm-C*-Sm-A phase in thin and planarly aligned cells in the frequency range 10Hz–10MHz. Here phason mode (Goldstone mode) and soft mode contribution in dielectric permittivity could not be clearly separated, near and slightly above the transition temperature Tc. If there is a contribution of phason mode after Tc in Sm-A phase then there is a possibility of getting memory even in Sm-A phase where the molecules get clamped in one direction and stay there even when the field has been removed. A comparative analysis of dielectric permittivity as well as texture in Sm-C* phase has been done on a virgin cell and on a cell in which bias has been applied in Sm-A phase just 1–2°C above Tc for 1min. The difference in dielectric permittivity and texture in the two different conditions clearly shows the continuance of memory effect from Sm-A phase to Sm-C* phase. The effect is probably due to local azimuthal variation in a finite range of Sm-A phase just above Tc.
Isomerization and dissociation dynamics of HCN in a picosecond infrared laser field: A full-dimensional classical study
Authors: Gong Jiangbin , Ma Ao , Rice Stuart A.
Published: April 2005

We report a full-dimensional study of the classical dynamics of HCN→HNC isomerization and of HCN rovibrational dissociation driven by a strong but nonionizing picosecond infrared laser field. The dynamics of the isolated molecule and of the molecule in liquid Ar have both been studied. Our theoretical and numerical results show that when all degrees of freedom are accounted for the field induced molecular dynamics can be totally different from what was found in previous studies, where the HCN molecule is restricted to a plane containing the external field. It is shown that as HCN is driven by an infrared laser field, the rotation of the H atom around the C–N bond provides an important and highly efficient energy absorption mechanism. In the presence of a monochromatic picosecond infrared laser field with an intensity of 1013W∕cm2, this energy absorption mechanism generates considerable HCN→HNC isomerization yield or high rovibrational dissociation yield without molecular preorientation or prealignment. Our study of the field induced isomerization and dissociation dynamics of the same system in liquid Ar shows that the picosecond isomerization dynamics is insignificantly affected by the surrounding atomic liquid whereas the dissociation yield may be greatly suppressed in a high density liquid. The implications of this study for full-dimensional quantum dynamics of multiphoton rovibrational excitation and dissociation of triatomics are briefly discussed.
Recent advances in the turbulent Rayleigh–Taylor instability
Authors: Dimonte Guy , Ramaprabhu P. , Youngs D. L. , Andrews M. J. , Rosner R.
Published: April 2005

In the turbulent Rayleigh–Taylor instability, the light fluid penetrates the heavy fluid as bubbles with a diameter Db and amplitude hb that grow self-similarly Db∝hb∼αbAgt2 where A is Atwood number, g is acceleration, and t is time. Experiments measure an acceleration constant αb∼0.04–0.08 whereas the highest resolution three-dimensional numerical simulations obtain αb∼0.02–0.03 with idealized initial conditions. This paper reconciles this apparent discrepancy with new simulations that quantify the importance of initial conditions on αb. The results compare favorably with experiments and a model based on self-similar bubble dynamics.
Valence double ionization of O2 at photon energies below and above the molecular double ionization threshold
Authors: Feifel R. , Eland J. H. D. , Edvardsson D.
Published: April 2005

A recently developed time-of-flight photoelectron–photoelectron coincidence spectroscopy technique, which gives complete two-dimensional e−–e− spectra in single photon double ionization, is applied to molecular oxygen at photon energies below and above the adiabatic double ionization threshold of O2. Analysis of the two-dimensional coincidence maps reveals specific indirect pathways for the double ionization process. Dissociative ionization paths with subsequent autoionization of atomic oxygen are found to be the dominant processes for all chosen photon energies. Spectra of the photoelectrons coincident with the autoionization electrons show that intermediate O2+ states are involved which do not autoionize to molecular O22+. In particular, the ground state of O22+ is vibrationally resolved and shows a regular progression which can be well described by direct Franck-Condon transitions at an internuclear distance Re(XΣg+1)=1.054Å. Quantum yields of double ionization for O2, of a form discussed in this paper, are determined.
Complete valence double photoionization of SF6
Authors: Feifel R. , Eland J. H. D. , Storchi L. , Tarantelli F.
Published: April 2005

Single photon double ionization of SF6 has been investigated at the photon energies 38.71, 40.814, and 48.372eV by using a recently developed time-of-flight photoelectron–photoelectron coincidence spectroscopy technique which gives complete two-dimensional e−–e− spectra. The first complete single photon double ionization electron spectrum of SF6 up to a binding energy of ∼48eV is presented and accurately interpreted with the aid of Green’s function ADC(2) calculations. Spectra which reflect either mainly direct or mainly indirect (via interatomic coulombic decay of F2s holes) double ionization of SF6 are extracted from the coincidence map and discussed. A previous, very low value for the onset of double ionization of SF6 is found to energetically coincide with a peak structure related to secondary inelastic scattering events.
Photophysics of aromatic molecules with low-lying πσ* states: Fluorinated benzenes
Authors: Zgierski Marek Z. , Fujiwara Takashige , Lim E. C.
Published: April 2005

Unlike fluorinated benzenes with four or less fluorine atoms, pentafluorobenzene (PFB) and hexafluorobenzene (HFB) exhibit very small fluorescence yields and short fluorescence lifetimes. These emission anomalies suggest that the nature of the first excited singlet (S1) state may be different for the two classes of fluorobenzenes. Consistent with this conjecture, the time-dependent density-functional theory calculations yield S1 state of ππ* character for fluorinated benzenes with four or less F atoms, and S1 state of πσ* character for PFB and HFB. The πσ* character of the S1 state of PFB and HFB has been confirmed by laser-induced fluorescence, which reveal the presence of a new electronic transition to the red of the π1π* (Lb)←S0 transition, which can be identified with the predicted low-energy π1σ*←S0 absorption. The low fluorescence yields and the short fluorescence lifetimes of PFB and HFB are consistent with the small radiative decay rate of the π1σ* state and efficient S1 (πσ*)→S0 internal conversion between two electronic states of very different geometries.
Determination of photophysical parameters from photon arrival time trajectories in single molecule fluorescence spectroscopy
Authors: Martyński Michal , Zydlewicz Jolanta , Boens Noël , Molski Andrzej
Published: April 2005

Triplet blinking is a phenomenon observed commonly in single molecule fluorescence spectroscopy. At high to moderate excitation intensities one can distinguish bright (on) and dark (off) periods in the fluorescence intensity trajectory caused by sojourns into the nonemissive triplet state. In this work, we focus on triplet blinking of an immobilized molecule in the low excitation regime, where a threshold between on and off intensity levels cannot be set, and, therefore, a standard on/off analysis of fluorescence intensity trajectories is not possible. In the low excitation regime triplet blinking parameters can be recovered from photon arrival time trajectories, i.e., records of individual photon arrival time. We use computer-generated data to compare the recovery of the triplet blinking parameters from the intensity correlation function (ICF) and the histogram of interarrival time. We have found that the ICF offers a better statistics for the recovery of the triplet blinking parameters.