bluuebunny/crossref_metadata_2025 huggingface dataset:
Yes/No Recognition, Forced-choice Recognition, and the Human Hippocampus
Authors: Bayley P. J. , Wixted J. T. , Hopkins R. O. , Squire L. R.
Published: November 2007

Two recent studies reported that yes/no recognition can be more impaired by hippocampal lesions than forced-choice recognition when the targets and foils are highly similar. This finding has been taken in support of two fundamental proposals: (1) yes/no recognition tests depend more on recollection than do forced-choice tests; and (2) the hippocampus selectively supports the recollection process. Using the same stimulus materials as in the earlier studies, we tested five memory-impaired patients with circumscribed hippocampal lesions and 15 controls. As in the earlier studies, participants studied 12 pictures of objects and then took either a 12-item forced-choice test with four alternatives or a 60-item yes/no test. Patients were impaired on both tests but did more poorly on the yes/no test. However, a yes/no test based on 12 study items would conventionally involve only 24 test items (i.e., 12 study items and 12 foil items). When we scored only the first 24 test items, the patients performed identically on the yes/no and forced-choice tests. Examination of the data in blocks of 12 trials indicated that the scores of the patients declined as testing continued. We suggest that a yes/no test of 60 items is difficult relative to a 12-item forced-choice test due to the increased study-test delay and due to increased interference, not because of any fundamental difference between the yes/no and forced-choice formats. We conclude that hippocampal lesions impair yes/no and forced-choice recognition to the same extent.
Remember/Know Judgments Probe Degrees of Recollection
Authors: Wais Peter E. , Mickes Laura , Wixted John T.
Published: November 2007

Remembering and knowing are states of awareness that accompany the retrieval of facts, faces, and experiences from our past. Although originally intended to separate episodic from semantic memory, the dominant view today is that recollection-based decisions underlie remember responses, whereas familiarity-based decisions underlie know responses. Many functional magnetic resonance imaging (fMRI) studies as well as lesion studies have relied on the remember/know procedure to identify the neural correlates of recollection and familiarity. An implicit assumption of this approach is that know responses, which are thought to tap familiarity-based decisions, are devoid of recollection. We investigated this issue by using a source memory procedure and found that the accuracy of source recollection was significantly above chance for studied words that were declared to be old and known. Critically, this held true even when the source decision was made before the old/new decision (i.e., even after successful recollection had just occurred). Our results show that although recollection and familiarity may be different processes, the remember/know paradigm does not probe them directly. As such, dissociations involving remember/know judgments in fMRI studies and in studies involving amnesic patients should not be construed as dissociations between recollection and familiarity.
Local Ensemble Transform Kalman Filtering with an AGCM at a T159/L48 Resolution
Authors: Miyoshi Takemasa , Yamane Shozo
Published: November 2007

A local ensemble transform Kalman filter (LETKF) is developed and assessed with the AGCM for the Earth Simulator at a T159 horizontal and 48-level vertical resolution (T159/L48), corresponding to a grid of 480 × 240 × 48. Following the description of the LETKF implementation, perfect model Observing Systems Simulation Experiments (OSSEs) with two kinds of observing networks and an experiment with real observations are performed. First, a regular observing network with approximately 1% observational coverage of the system dimension is applied to investigate computational efficiency and sensitivities with the ensemble size (up to 1000) and localization scale. A 10-member ensemble is large enough to prevent filter divergence. Using 20 or more members significantly stabilizes the filter, with the analysis errors less than half as large as the observation errors. There is nonnegligible dependence on the localization scale; tuning is suggested for a chosen ensemble size. The sensitivities of analysis accuracies and timing on the localization parameters are investigated systematically. A computational parallelizing ratio as large as 99.99% is achieved. Timing per analysis is less than 4 min on the Earth Simulator, peak performance of 64 GFlops per computational node, provided that the same number of nodes as the ensemble size is used, and the ensemble size is less than 80. In the other set of OSSEs, the ensemble size is fixed to 40, and the real observational errors and locations are adapted from the Japan Meteorological Agency’s (JMA’s) operational numerical weather prediction system. The analysis errors are as small as 0.5 hPa, 2.0 m s−1, and 1.0 K in major areas for sea level pressure, zonal and meridional winds, and temperature, respectively. Larger errors are observed in data-poor regions. The ensemble spreads capture the actual error structures, generally representing the observing network. However, the spreads are larger than the actual errors in the Southern Hemisphere; the opposite is true in the Tropics, which suggests the spatial dependence of the optimal covariance inflation. Finally, real observations are assimilated. The analysis fields look almost identical to the JMA operational analysis; 48-h forecast experiments initiated from the LETKF analysis, JMA operational analysis, and NCEP–NCAR reanalysis are performed, and the forecasts are compared with their own analyses. The 48-h forecast verifications suggest a similar level of accuracy when comparing LETKF to the operational systems. Overall, LETKF shows encouraging results in this study.
Radar and Lightning Observations of Normal and Inverted Polarity Multicellular Storms from STEPS
Authors: Tessendorf Sarah A. , Rutledge Steven A. , Wiens Kyle C.
Published: November 2007

This study discusses radar and lightning observations of two multicellular storms observed during the Severe Thunderstorm Electrification and Precipitation Study. The Lightning Mapping Array data indicated that the charge structure of the 19 June 2000 storm was consistent with a normal polarity tripole, while the 22 June 2000 storm exhibited an overall inverted tripolar charge structure. The 19 June storm consisted of weaker convection and produced little to no hail and moderate total flash rates peaking between 80 and 120 min−1. The cells in the 22 June 2000 storm were much more vigorous, exhibited strong, broad updrafts, and produced large quantities of hail, as well as extraordinary total flash rates as high as 500 min−1. The National Lightning Detection Network (NLDN) indicated that the 19 June storm produced mostly negative cloud-to-ground (CG) lightning, while the 22 June storm produced predominantly positive CG lightning, peaking at 10 min−1 just after two cells merged. However, the Los Alamos Sferic Array indicated that many of the positive CG strokes reported by the NLDN in the 22 June storm were intracloud discharges known as narrow bipolar events. Negative CG lightning was also observed in the 22 June storm, but typically came to ground beneath an inverted dipole in the storm anvil.
An Investigation of Cross-Cultural Differences on the Impact of Productivity Interventions: The Example of ProMES
Authors: Paquin Anthony R. , Roch Sylvia G. , Sanchez-Ku Maria L.
Published: November 2007

The success of a productivity intervention may depend on the fit between the intervention and the country in which it is implemented. In particular, a country's horizontal collectivism may influence the intervention's effectiveness. Results based on a database of 90 organizational units from seven different countries in which ProMES, a productivity intervention, was implemented indicated that in general, ProMES is more successful in some European countries than in the United States. Furthermore, results indicate that this effect may be due to an interaction between power distance and social collectivism. The degree of collectivism plays an important role in predicting whether ProMES succeeds in countries with relatively low power distance. In countries that score relatively high in power distance, the intervention succeeds regardless of the degree of collectivism. Lastly, whether a country's level of uncertainty avoidance has implications for the success of ProMES is also explored. Implications are discussed.
Assessing the Trends and Challenges of Teaching Marketing Abroad: A Delphi Approach
Authors: Kelley Craig A.
Published: November 2007

The past 20 years have seen a growth in the teaching of marketing in business schools around the world. This article reports the trends and challenges that will face U.S. marketing educators teaching abroad over the next 10 years. Predictions are from a Delphi panel of U.S. marketing educators experienced in teaching marketing abroad to non-U.S. students who are predominately natives of the host country. The Delphi panelists predict that growing global expansion of non-U.S. business schools will limit the opportunities for U.S. marketing educators to teach abroad, as educators at the host schools will teach more of their own native students. In addition, increasingly demanding students who enroll in marketing programs around the world will require U.S. marketing educators to tailor course content to include local marketing practices, accommodate different learning styles, and use teaching methods preferred by native students in delivering their courses.
A Study of the Database Marketing Course in AACSB–Accredited Business Schools
Authors: Teer Harold B. , Teer Faye P. , Kruck S. E.
Published: November 2007

This article presents findings of an empirical investigation of the database marketing (DBM) course in business schools within the United States accredited by the Association to Advance Collegiate Schools of Business. Results indicated that from 2001 to 2005 there was a 52.5% increase in the percentage of business schools o fering an undergraduate DBM course and that the content of the DBM course had changed. The major change in topical coverage in the DBM course over the time frame studied was the addition of ethics coverage. There was also an increase in the amount of coverage in the course for areas such as lifetime value of a customer, direct marketing, data warehousing, market segmentation, and customer relationship marketing. During the 4 years between surveys, the analytical techniques covered in class stayed essentially the same with the exception of cross-tabs, in which theoretical and hands-on use increased greatly.
Applied Creativity: The Creative Marketing Breakthrough Model
Authors: Titus Philip A.
Published: November 2007

Despite the increasing importance of personal creativity in today's business environment, few conceptual creativity frameworks have been presented in the marketing education literature. The purpose of this article is to advance the integration of creativity instruction into marketing classrooms by presenting an applied creative marketing framework. The theoretical basis for the creativity framework, referred to as the creative marketing breakthrough model, is discussed along with its pedagogical implications for marketing education. Furthermore, an illustrated instructional example is provided to highlight the impact of the creative marketing breakthrough model constructs on individual creative performance.
Distinguishing Between Depression and Dementia in Older Persons: Neuropsychological and Neuropathological Correlates
Authors: Wright Sara L. , Persad Carol
Published: November 2007

Dementia and depression are frequently comorbid among older adult patients. Depression is related to cognitive decrement and can even represent the first signs of a neurodegenerative process. It can be difficult to distinguish depressed patients exhibiting the first signs of dementia from those whose cognition will improve with treatment. In this article, studies from the neuropsychological literature are reviewed that aid in accurate diagnosis and prognosis. Furthermore, the relationship between depression and dementia is explored by examining potential neurobiological mechanisms that may potentiate both syndromes in the context of the ongoing debate on depression as a prodrome and/or a risk factor for dementia. This article is concluded with suggestions for clinicians when deciding who to refer for neuropsychological assessment and with ideas for further research that might promote a better understanding of the complex association between depression and dementia during old age. ( J Geriatr Psychiatry Neurol 2007;20:189-198)
Neurocognitive Costs and Benefits of Psychotropic Medications in Older Adults
Authors: Brooks John O. , Hoblyn Jennifer C.
Published: November 2007

Psychotropic medications are widely used in older adults and may cause neurocognitive deficits. Older adults are at increased risk of developing adverse effects because of age-related pharmacodynamic and pharmacokinetic changes. This article provides a comprehensive review of the undesirable, and at times beneficial, effects of psychotropic medications. The review covers a wide range of medications that impair executive function, memory, and attention, as well as a much smaller group of medications that lead to improved neurocognitive function. Some of the most commonly used psychotropic medications in older adults, namely, antidepressants, sedatives, and hypnotics, are among the drugs that most consistently lead to cognitive impairments. Medications with anticholinergic properties almost invariably lead to neurocognitive dysfunction, despite symptom improvement. The neurocognitive costs and benefits of psychiatric medications should be considered in the context of disease treatment in older adults. ( J Geriatr Psychiatry Neurol 2007;20:199—214)
Mild Cognitive Dysfunction: An Epidemiological Perspective With an Emphasis on African Americans
Authors: Unverzagt Frederick W. , Sujuan Gao  , Lane Kathleen A. , Callahan Christopher , Ogunniyi Adesola , Baiyewu Olusegun , Gureje Oye , Hall Kathleen S. , Hendrie Hugh C.
Published: November 2007

This review begins with a historical accounting of the evolution of the concept of mild cognitive dysfunction, including nomenclature and criteria from Kral to Petersen. A critical analysis of the main elements relating to assessment and diagnosis of mild cognitive dysfunction is provided. Methodological limitations in design, measurement, and characterization, especially as they relate to older African Americans, are identified. Data from a 15-year longitudinal study of community-dwelling African Americans in Indianapolis, Indiana, indicate a 23% prevalence of all-cause mild cognitive dysfunction, with approximately 25% progressing to dementia in 2 years and another 25% reverting to normal cognition in the same interval. Factors contributing to this longitudinal variability in outcomes are reviewed, including the role of medical health factors. The review closes with suggestions for next steps in the epidemiological research of mild cognitive impairment. ( J Geriatr Psychiatry Neurol 2007;20:215—226)
Nonpharmacological Cognitive Interventions in Aging and Dementia
Authors: Acevedo Amarilis , Loewenstein David A.
Published: November 2007

There have been increasing efforts to develop cognitive interventions to ameliorate cognitive problems experienced by older adults. In healthy elderly populations, cognitive training has centered on the enhancement of memory and speed of processing, with the goal of maximizing current function and reducing the risk of cognitive decline. Among elderly persons with nonprogressive neurological conditions such as traumatic brain injury (TBI) and stroke, there has been an emphasis on rehabilitation to help restore function. Most recently, there has been increased attention on the development of new cognitive techniques to treat persons with progressive neurodegenerative conditions such as Alzheimer disease. The literature is reviewed on current approaches to cognitive interventions in elderly healthy populations, and a particular emphasis is placed on the most recent strides in progressive neurocognitive conditions, particularly Alzheimer disease. Important issues such as study design, the use of ecologically and functionally valid outcome measures, the need to examine heterogeneous populations and cross-cultural variables, and the incorporation of technologically based systems are examined. It is concluded that cognitive interventions in the elderly show considerable promise and deserve further study. ( J Geriatr Psychiatry Neurol 2007;20:239—249)
uneasy relationships?
Authors: Kiwan Dina
Published: November 2007

Multicultural societies such as the UK typically claim to embrace a model of `participative', `inclusive' and `democratic' citizenship. In this article, I examine conceptions of participative citizenship, democracy and diversity and how they inter-relate in the citizenship education policymaking process in England. I illustrate that the dominant model of citizenship is `participatory', linked to the concept of democracy. However, `diversity' is not explicitly addressed within the participatory conception, nor in relation to democracy. I discuss some of the theoretical tensions between participation, democracy and diversity. Drawing on Young's (2000) concept of `deliberative democracy', I highlight two themes — the public—private sphere distinction, and `shared values' which are particularly pertinent in considering citizenship in ethnically and religiously diverse contexts. I conclude by proposing that citizenship education should focus on the process of inclusive communication and collective problem-solving, rather than a privileging of a substantive `common good' or `shared values'.
STAT1 signaling modulates HIV-1–induced inflammatory responses and leukocyte transmigration across the blood-brain barrier
Authors: Chaudhuri Anathbandhu , Yang Bo , Gendelman Howard E. , Persidsky Yuri , Kanmogne Georgette D.
Published: November 2007

The relationship among neuroinflammation, blood-brain barrier (BBB) dysfunction, and progressive HIV-1 infection as they affect the onset and development of neuroAIDS is incompletely understood. One possible link is signal transducers and activators of transcription (STATs) pathways. These respond to proinflammatory and regulatory factors and could affect neuroinflammatory responses induced from infected cells and disease-affected brain tissue. Our previous works demonstrated that HIV-1 activates pro-inflammatory and interferon-alpha–inducible genes in human brain microvascular endothelial cells (HBMECs) and that these genes are linked to the Janus kinase (JAK)/STAT pathway. We now demonstrate that HIV-1 activates STAT1, induces IL-6 expression, and diminishes expression of claudin-5, ZO-1, and ZO-2 in HBMECs. The STAT1 inhibitor, fludarabine, blocked HIV-1–induced IL-6, diminished HIV-1–induced claudin-5 and ZO-1 down-regulation, and blocked HIV-1– and IL-6–induced monocyte migration across a BBB model. Enhanced expression and activation of STAT1 and decreased claudin-5 were observed in microvessels from autopsied brains of patients with HIV-1–associated dementia. These data support the notion that STAT1 plays an integral role in HIV-1–induced BBB damage and is relevant to viral neuropathogenesis. Inhibition of STAT1 activation could provide a unique therapeutic strategy to attenuate HIV-1–induced BBB compromise and as such improve clinical outcomes.
Steady-state dendritic cells expressing cognate antigen terminate memory CD8+ T-cell responses
Authors: Kenna Tony J. , Thomas Ranjeny , Steptoe Raymond J.
Published: November 2007

Antigen stimulation of naive T cells in conjunction with strong costimulatory signals elicits the generation of effector and memory populations. Such terminal differentiation transforms naive T cells capable of differentiating along several terminal pathways in response to pertinent environmental cues into cells that have lost developmental plasticity and exhibit heightened responsiveness. Because these cells exhibit little or no need for the strong costimulatory signals required for full activation of naive T cells, it is generally considered memory and effector T cells are released from the capacity to be inactivated. Here, we show that steady-state dendritic cells constitutively presenting an endogenously expressed antigen inactivate fully differentiated memory and effector CD8+ T cells in vivo through deletion and inactivation. These findings indicate that fully differentiated effector and memory T cells exhibit a previously unappreciated level of plasticity and provide insight into how memory and effector T-cell populations may be regulated.
Novel definition files for human GeneChips based on GeneAnnot
Authors: Ferrari Francesco , Bortoluzzi Stefania , Coppe Alessandro , Sirota Alexandra , Safran Marilyn , Shmoish Michael , Ferrari Sergio , Lancet Doron , Danieli Gian Antonio , Bicciato Silvio
Published: November 2007

Background

Improvements in genome sequence annotation revealed discrepancies in the original probeset/gene assignment in Affymetrix microarray and the existence of differences between annotations and effective alignments of probes and transcription products. In the current generation of Affymetrix human GeneChips, most probesets include probes matching transcripts from more than one gene and probes which do not match any transcribed sequence.

Results

We developed a novel set of custom Chip Definition Files (CDF) and the corresponding Bioconductor libraries for Affymetrix human GeneChips, based on the information contained in the GeneAnnot database. GeneAnnot-based CDFs are composed of unique custom-probesets, including only probes matching a single gene.

Conclusion

GeneAnnot-based custom CDFs solve the problem of a reliable reconstruction of expression levels and eliminate the existence of more than one probeset per gene, which often leads to discordant expression signals for the same transcript when gene differential expression is the focus of the analysis. GeneAnnot CDFs are freely distributed and fully compliant with Affymetrix standards and all available software for gene expression analysis. The CDF libraries are available from http://www.xlab.unimo.it/GA_CDF, along with supplementary information (CDF libraries, installation guidelines and R code, CDF statistics, and analysis results).
Disparities in appendicitis rupture rate among mentally ill patients
Authors: Tsay Jen-Huoy , Lee Cheng-Hua , Hsu Yea-Jen , Wang Pen-Jen , Bai Ya-Mei , Chou Yiing-Jenq , Huang Nicole
Published: November 2007

Background

Many studies have been carried out that focus on mental patients' access to care for their mental illness, but very few pay attention on these same patients' access to care for their physical diseases. Acute appendicitis is a common surgical emergency. Our population-based study was to test for any possible association between mental illness and perforated appendicitis. We hypothesized that there are significant disparities in access to timely surgical care between appendicitis patients with and without mental illness, and more specifically, between patients with schizophrenia and those with another major mental illness.

Methods

Using the National Health Insurance (NHI) hospital-discharge data, we compared the likelihood of perforated appendix among 97,589 adults aged 15 and over who were hospitalized for acute appendicitis in Taiwan between the years 1997 to 2001. Among all the patients admitted for appendicitis, the outcome measure was the odds of appendiceal rupture vs. appendicitis that did not result in a ruptured appendix.

Results

After adjusting for age, gender, ethnicity, socioeconomic status (SES) and hospital characteristics, the presence of schizophrenia was associated with a 2.83 times higher risk of having a ruptured appendix (odds ratio [OR], 2.83; 95% confidence interval [CI], 2.20–3.64). However, the presence of affective psychoses (OR, 1.15; 95% CI: 0.77–1.73) or other mental disorders (OR, 1.58; 95% CI: 0.89–2.81) was not a significant predictor for a ruptured appendix.

Conclusion

These findings suggest that given the fact that the NHI program reduces financial barriers to care for mentally ill patients, they are still at a disadvantage for obtaining timely treatment for their physical diseases. Of patients with a major mental illness, schizophrenic patients may be the most vulnerable ones for obtaining timely surgical care.
Evaluating an educational intervention to improve the accuracy of death certification among trainees from various specialties
Authors: Villar Jesús , Pérez-Méndez Lina
Published: November 2007

Background

The inaccuracy of death certification can lead to the misallocation of resources in health care programs and research. We evaluated the rate of errors in the completion of death certificates among medical residents from various specialties, before and after an educational intervention which was designed to improve the accuracy in the certification of the cause of death.

Methods

A 90-min seminar was delivered to seven mixed groups of medical trainees (n = 166) from several health care institutions in Spain. Physicians were asked to read and anonymously complete a same case-scenario of death certification before and after the seminar. We compared the rates of errors and the impact of the educational intervention before and after the seminar.

Results

A total of 332 death certificates (166 completed before and 166 completed after the intervention) were audited. Death certificates were completed with errors by 71.1% of the physicians before the educational intervention. Following the seminar, the proportion of death certificates with errors decreased to 9% (p < 0.0001). The most common error in the completion of death certificates was the listing of the mechanism of death instead of the cause of death. Before the seminar, 56.8% listed respiratory or cardiac arrest as the immediate cause of death. None of the participants listed any mechanism of death after the educational intervention (p < 0.0001).

Conclusion

Major errors in the completion of the correct cause of death on death certificates are common among medical residents. A simple educational intervention can dramatically improve the accuracy in the completion of death certificates by physicians.
The most dangerous hospital or the most dangerous equation?
Authors: Tu Yu-Kang , Gilthorpe Mark S
Published: November 2007

Background

Hospital mortality rates are one of the most frequently selected indicators for measuring the performance of NHS Trusts. A recent article in a national newspaper named the hospital with the highest or lowest mortality in the 2005/6 financial year; a report by the organization Dr Foster Intelligence provided information with regard to the performance of all NHS Trusts in England.

Methods

Basic statistical theory and computer simulations were used to explore the relationship between the variations in the performance of NHS Trusts and the sizes of the Trusts. Data of hospital standardised mortality ratio (HSMR) of 152 English NHS Trusts for 2005/6 were re-analysed.

Results

A close examination of the information reveals a pattern which is consistent with a statistical phenomenon, discovered by the French mathematician de Moivre nearly 300 years ago, described in every introductory statistics textbook: namely that variation in performance indicators is expected to be greater in small Trusts and smaller in large Trusts. From a statistical viewpoint, the number of deaths in a hospital is not in proportion to the size of the hospital, but is proportional to the square root of its size. Therefore, it is not surprising to note that small hospitals are more likely to occur at the top and the bottom of league tables, whilst mortality rates are independent of hospital sizes.

Conclusion

This statistical phenomenon needs to be taken into account in the comparison of hospital Trusts performance, especially with regard to policy decisions.
Social mobilisation, drug coverage and compliance and adverse reactions in a Mass Drug Administration (MDA) Programme for the Elimination of Lymphatic Filariasis in Sri Lanka
Authors: Weerasooriya Mirani V , Yahathugoda Channa T , Wickramasinghe Darshana , Gunawardena Kithsiri N , Dharmadasa Rohan A , Vidanapathirana Kanchana K , Weerasekara Saman H , Samarawickrema Wilfred A
Published: November 2007

Background

In Sri Lanka filariasis is endemic in Southern, Western and North Western provinces covering eight districts designated as implementation units in the Programme for the Elimination of Lymphatic Filariasis (PELF). Despite control activities over sixty years including multidose diethylcarbamazine, 6 mg/kg treatment microfilaria rates had persisted at low levels. Following systematic social mobilisation the first MDA with DEC albendazole combination was conducted in 2002.

Methods

We investigated the extent social mobilisation had reached the people, their drug compliance and adverse reactions. Three localities were selected from each district to pick target population samples for pre-tested questionnaire. Three teams each with six people visited one district each day. One team worked from three starting points in one locality. A member applied eight part questionnaire to one family member totalling 150–160 people from one locality. Questions included social mobilisation, drug compliance and adverse reactions.

Results

Information was disseminated by television, radio, banners and leaflets, to a lesser extent by people. Information reached more people in the periphery than in Colombo. 35.2% from Colombo municipality were unaware of the MDA. Drug coverage was 79.6%, home delivery 71.7% and delivery centres 7.9%. 35.6% in Colombo district and 53.4% from Colombo municipality did not receive drugs. Drugs were consumed by 71.4%. 28.6% who did not comply included 20.4% who did not receive them. 91.4% showed no adverse reactions, 7.5% were mild, 1.1% recovered with home remedies.

Conclusion

Drug compliance showed significant positive correlation with awareness of the MDA. Door to door delivery was more successful than delivery from centres. More delivery centres conveniently located would have rectified this disparity. Poor awareness and compliance in Colombo and urban areas could be rectified with separate strategy for urban areas. More time for MDA and trained adequate manpower would ensure coverage to achieve elimination.
Adaptive sequence evolution in a color gene involved in the formation of the characteristic egg-dummies of male haplochromine cichlid fishes
Authors: Salzburger Walter , Braasch Ingo , Meyer Axel
Published: November 2007

Background

The exceptionally diverse species flocks of cichlid fishes in East Africa are prime examples of parallel adaptive radiations. About 80% of East Africa's more than 1 800 endemic cichlid species, and all species of the flocks of Lakes Victoria and Malawi, belong to a particularly rapidly evolving lineage, the haplochromines. One characteristic feature of the haplochromines is their possession of egg-dummies on the males' anal fins. These egg-spots mimic real eggs and play an important role in the mating system of these maternal mouthbrooding fish.

Results

Here, we show that the egg-spots of haplochromines are made up of yellow pigment cells, xanthophores, and that a gene coding for a type III receptor tyrosine kinase,colony-stimulating factor 1 receptor a(csf1ra), is expressed in egg-spot tissue. Molecular evolutionary analyses reveal that the extracellular ligand-binding and receptor-interacting domain ofcsf1raunderwent adaptive sequence evolution in the ancestral lineage of the haplochromines, coinciding with the emergence of egg-dummies. We also find thatcsf1rais expressed in the egg-dummies of a distantly related cichlid species, the ectodine cichlidOphthalmotilapia ventralis, in which markings with similar functions evolved on the pelvic fin in convergence to those of the haplochromines.

Conclusion

We conclude that modifications of existing signal transduction mechanisms might have evolved in the haplochromine lineage in association with the origination of anal fin egg-dummies. That positive selection has acted during the evolution of a color gene that seems to be involved in the morphogenesis of a sexually selected trait, the egg-dummies, highlights the importance of further investigations of the comparative genomic basis of the phenotypic diversification of cichlid fishes.
Optimal organ-sparing intensity-modulated radiation therapy (IMRT) regimen for the treatment of locally advanced anal canal carcinoma: a comparison of conventional and IMRT plans
Authors: Menkarios Cathy , Azria David , Laliberté Benoit , Moscardo Carmen Llacer , Gourgou Sophie , Lemanski Claire , Dubois Jean-Bernard , Aillères Norbert , Fenoglietto Pascal
Published: November 2007

Background

To compare the dosimetric advantage of three different intensity-modulated radiation therapy (IMRT) plans to a three dimensional (3D) conventional radiation treatment for anal cancer with regards to organs-at-risk (OAR) avoidance, including iliac bone marrow.

Methods

Five patients with T1-3 N0-1 anal cancer and five with T4 and/or N2-3 tumors were selected. Clinical tumor volume (CTV) included tumor, anal canal and inguinal, peri-rectal, and internal/external iliac nodes (plus pre-sacral nodes for T4/N2-3 tumors). Four plans were generated: (A) AP/PA with 3D conformal boost, (B) pelvic IMRT with conformal boost (C) pelvic IMRT with IMRT boost and (D) IMRT with simultaneous integrated boost (SIB). The dose for plans (A) to (C) was 45 Gy/25 followed by a 14.4 Gy/8 boost, and the total dose for plan (D) (SIB) was 59.4 Gy/33. Coverage of both PTV and the volume of OAR (small bowel, genitalia, iliac crest and femoral heads) receiving more than 10, 20, 30, and 40 Gy (V10, V20, V30, V40) were compared using non parametric statistics.

Results

Compared to plan (A), IMRT plans (B) to (D) significantly reduced the V30 and V40 of small bowel, bladder and genitalia for all patients. The V10 and V20 of iliac crests were similar for the N0-1 group but were significantly reduced with IMRT for the N2-3/T4 group (V20 for A = 50.2% compared to B = 33%, C = 32.8%, D = 34.3%). There was no statistical difference between 2-phase (arm C) and single-phase (SIB, arm D) IMRT plans.

Conclusion

IMRT is superior to 3D conformal radiation treatment for anal carcinoma with respect to OAR sparing, including bone marrow sparing.
Lymph heart in chick - somitic origin, development and embryonic oedema
Authors: Valasek Petr , Macharia Raymond , Neuhuber Winfried L. , Wilting Joerg , Becker David L. , Patel Ketan
Published: November 2007

The lymph heart is a sac-like structure on either side of avian tail. In some adult birds, it empties the lymph from the copulatory organ; however,during embryonic development, it is thought to circulate extra-embryonic lymph. Very little is known about the origin, innervation and the cellular changes it undergoes during development. Using immunohistochemistry and gene expression profiling we show that the musculature of the lymph heart is initially composed solely of striated skeletal muscle but later develops an additional layer composed of smooth myofibroblasts. Chick-quail fate-mapping demonstrates that the lymph heart originates from the hypaxial compartments of somites 34-41. The embryonic lymph heart is transiently innervated by somatic motoneurons with no autonomic input. In comparison to body muscles, the lymph heart has different sensitivity to neuromuscular junction blockers (sensitive only to decamethonium). Furthermore, its abundant bungarotoxin-positive acetylcholinesterase receptors are unique as they completely lack specific acetylcholinesterase activity. Several lines of evidence suggest that the lymph heart may possess an intrinsic pacing mechanism. Finally, we assessed the function of the lymph heart during embryogenesis and demonstrate that it is responsible for preventing embryonic oedema in birds, a role previously thought to be played by body skeletal muscle contractions.
Cessation of gastrulation is mediated by suppression of epithelial-mesenchymal transition at the ventral ectodermal ridge
Authors: Ohta Sho , Suzuki Kentaro , Tachibana Katsuro , Tanaka Hideaki , Yamada Gen
Published: November 2007

In the gastrula stage embryo, the epiblast migrates toward the primitive streak and ingresses through the primitive groove. Subsequently, the ingressing epiblast cells undergo epithelial-mesenchymal transition (EMT) and differentiate into the definitive endoderm and mesoderm during gastrulation. However, the developmental mechanisms at the end of gastrulation have not yet been elucidated. Histological and genetic analyses of the ventral ectodermal ridge (VER), a derivative of the primitive streak, were performed using chick and mouse embryos. The analyses showed a continued cell movement resembling gastrulation associated with EMT during the early tailbud stage of both embryos. Such gastrulation-like cell movement was gradually attenuated by the absence of EMT during tail development. The kinetics of the expression pattern of noggin (Nog) and basal membrane degradation adjacent to the chick and the mouse VER indicated a correlation between the temporal and/or spatial expression of Nog and the presence of EMT in the VER. Furthermore, Nog overexpression suppressed EMT and arrested ingressive cell movement in the chick VER. Mice mutant in noggin displayed dysregulation of EMT with continued ingressive cell movement. These indicate that the inhibition of Bmp signaling by temporal and/or spatial Nog expression suppresses EMT and leads to the cessation of the ingressive cell movement from the VER at the end of gastrulation.
Notch-GATA synergy promotes endoderm-specific expression ofref-1inC. elegans
Authors: Neves Alexandre , English Kathryn , Priess James R.
Published: November 2007

The Notch signaling pathway is involved in a wide variety of cell-fate decisions during development. The diverse behavior of Notch-activated cells is thought to depend on tissue- or cell-type-specific transcription factors, yet the identities of such factors and the mechanism of cooperation with the Notch pathway are largely unknown. We identify here an enhancer in the promoter of ref-1, a C. elegans Notch target, which promotes Notch-dependent expression in mesodermal and endodermal cells. The enhancer contains predicted binding sites for the Notch transcriptional effector LAG-1/CSL that are essential for expression, a non-CSL site required for mesodermal expression, and four predicted binding sites for GATA transcription factors that are required for endodermal expression. We show that endodermal expression involves the GATA transcription factor ELT-2, and that ELT-2 can bind LAG-1/CSL in vitro. In many types of Notch-activated embryonic cells,ectopic ELT-2 is sufficient to drive expression of reporters containing the enhancer.
Interferon-γ and tumor necrosis factor-α sensitize primarily resistant human endometrial stromal cells to Fas-mediated apoptosis
Authors: Fluhr Herbert , Krenzer Stefanie , Stein Gerburg M. , Stork Björn , Deperschmidt Margarita , Wallwiener Diethelm , Wesselborg Sebastian , Zygmunt Marek , Licht Peter
Published: November 2007

The subtle interaction between the implanting embryo and the maternal endometrium plays a pivotal role during the process of implantation. Human endometrial stromal cells (ESCs) express Fas and the implanting trophoblast cells secrete Fas ligand (FASLG, FasL), suggesting a possible role for Fas-mediated signaling during early implantation. Here we show that ESCs are primarily resistant to Fas-mediated apoptosis independently of their state of hormonal differentiation. Pre-treatment of ESCs with interferon (IFN)-γ and tumor necrosis factor (TNF)-α sensitizes them to become apoptotic upon stimulation of Fas by an agonistic anti-Fas antibody. Incubation of ESCs with the early embryonic signal human chorionic gonadotropin (hCG, CGB) does not influence their reaction to Fas stimulation. The sensitizing effect of IFN-γ and TNF-α was accompanied by a significant upregulation of Fas and FLICE-inhibitory protein (FLIP, CFLAR) expression in ESCs. Additionally, we observed an activation of caspase 3, caspase 8 and caspase 9 upon apoptotic Fas triggering. In summary, we demonstrate that IFN-γ and TNF-α sensitize primarily apoptosis-resistant ESCs to Fas-mediated cell death. This might be due to an upregulation of Fas expression, and apoptosis seems to be mediated by active caspase 3, caspase 8 and caspase 9. The observed pro-apoptotic effect of IFN-γ and TNF-α on ESCs could play an important role in the modulation of early implantation.
The complete removal of cohesin from chromosome arms depends on separase
Authors: Nakajima Masato , Kumada Kazuki , Hatakeyama Katsuyoshi , Noda Tetsuo , Peters Jan-Michael , Hirota Toru
Published: November 2007

Cohesin needs to be removed from chromosomes to allow sister chromatid separation in mitosis. In vertebrates, two pathways contribute to this process. The prophase pathway, which requires phosphorylation of the cohesin subunit SA2 and a cohesin-binding protein, called Wapl, removes the bulk of cohesin from the chromosome arms in early mitosis and allows the resolution of the chromosome arms. At anaphase onset, the protease separase removes centromere-enriched cohesin by proteolytic cleavage of another cohesin subunit, Scc1 (Rad21, Mcd1), which allows the separation of sister chromatids. When anaphase onset is delayed by the spindle-assembly checkpoint, the complete removal of cohesin from chromosome arms but not from centromeres generates typical X- or V-shaped chromosomes. Here, we found that cohesion between chromosome arms is preserved if mitosis is arrested with the proteasome inhibitor MG132. This arm cohesion depends on cohesin complexes that are protected by the shugoshin protein Sgo1, which appears to be distributed on chromosome arms as well as on centromeres in early mitosis. In cells lacking separase or expressing non-cleavable Scc1, arm cohesion was not efficiently removed during nocodazole arrest. Our observations suggest that a fraction of arm cohesin is protected by Sgo1, which prevents cohesin from being removed by the prophase pathway, and that separase is partly activated in nocodazole-arrested cells and removes the arm cohesin protected by Sgo1.
In vivo movement of the type V myosin Myo52 requires dimerisation but is independent of the neck domain
Authors: Grallert Agnes , Martín-García Rebeca , Bagley Steve , Mulvihill Daniel P.
Published: November 2007

Intracellular movement is a fundamental property of all cell types. Many organelles and molecules are actively transported throughout the cytoplasm by molecular motors, such as the dimeric type V myosins. These possess a long neck, which contains an IQ motif, that allow it to make 36-nm steps along the actin polymer. Live cell imaging of the fission yeast type V myosin Myo52 reveals that the protein moves rapidly throughout the cytoplasm. Here, we describe analysis of this movement and have established that Myo52 moves long distances on actin filaments in an ATP-dependent manner at ∼0.5 μm/second. Myo51 and the microtubule cytoskeleton have no discernable role in modulating Myo52 movements, whereas rigour mutations in Myo52 abrogated its movement. We go on to show that, although dimerisation is required for Myo52 movement, deleting its neck has no discernable affect on Myo52 function or velocity in vivo.
Identification of kinematic chains and distinct mechanisms using extended adjacency matrix
Authors: Mohammad A , Khan R A , Agrawal V P
Published: November 2007

Development of the methods for generating distinct mechanisms derived from a given family of kinematic chains has been persued by a number of researchers in the past, as the distinct kinematic structures provide distinct performance characteristics. A new method is proposed to identify the distinct mechanisms derived from a given kinematic chain in this paper. Kinematic chains and their derived mechanisms are represented in the form of an extended adjacency matrix [EA] using the graph theoretic approach. Two structural invariants derived from the eigen spectrum of the [EA] matrix are the sum of absolute eigen values EA∑ and maximum absolute eigen value EAmax. These invariants are used as the composite identification number of a kinematic chain and mechanism and are tested to identify the all-distinct mechanisms derived from the family of 1-F kinematic chains up to 10 links. The identification of distinct kinematic chains and their mechanisms is necessary to select the best possible mechanism for the specified task at the conceptual stage of design.
Research on shaft strength considering offsetting distribution of film pressure of journal bearing in shaft-bearing system
Authors: Jun S , Changlin G , Jingfeng W
Published: November 2007

There is a direct interaction between shaft and bearing in shaft-bearing system. The effect of lubrication status of bearing was not considered in the present calculation of shaft strength. In this paper, shaft-bearing system was taken as the study object. Hydrodynamic lubrication characteristics of a journal bearing considering misalignment caused by shaft deformation in shaft-bearing system were analysed. There are obvious offsetting distribution of film pressure and increase of the highest film pressure when journal misalignment takes place. Based on the lubrication analysis of bearing, the stress distribution of shaft was calculated when the film pressure calculated was used as boundary condition of load. The results show that there are obvious changes of stress distribution and great increase of stress near the area on shaft where it is acted upon the highest film pressure when considering the offsetting distribution of film pressure. The shaft strength is affected remarkably. Therefore, in order to accord with the tendency today for high precision in the design calculation, thus more reasonable design can be acquired, the coupling between the analysis of bearing tribology and the analysis of strength and stiffness of shaft must be studied in the design of shaft-bearing system.
Energy flow in jerk-decoupled translatory feed axes
Authors: Denkena B , Möhring H-C , Hesse P
Published: November 2007

This paper describes the energy flow in jerk-decoupled translatory feed axes. After an introductory survey on jerk-decoupled feed axes, a system simulation is presented. This system simulation includes a model of the mechanical parts, a model of a synchronous linear motor, and a model of the control circuits. Different energy flows can be simulated using an energy observer. The results are shown in the last section of this paper. With these results, an energy-optimal design of jerk-decoupled linear feed axes can be accomplished.
Robust controller based on friction compensation and disturbance observer for a motion platform driven by a linear motor
Authors: Wang Ying , Xiong Zhenhua , Ding Han
Published: November 2007

Non-linear friction and external disturbances affect the positioning accuracy of high-speed motion systems, especially of those impelled by linear motors. This paper presents a controller, which includes three parts: a proportional-plus-derivative (PD) feedback controller, a friction compensator, and a disturbance observer. The friction compensator is based on the LuGre model and compensates for non-linear friction. The disturbance observer is used to eliminate the friction compensation error and other external disturbances. Experimental results show that the controller gives high positioning accuracy and robust performance in the presence of disturbances for high acceleration motion over 5G.