bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology Readiness, Learning Goals, and eLearning: Searching for Synergy
Authors: Van Der Rhee Bo , Verma Rohit , Plaschka Gerhard R. , Kickul Jill R.
Published: February 2007

More and more business schools are offering classes online or classes using a mix of face‐to‐face and online elements. In this article, we focus on how technology readiness and learning‐goal orientation influence students' preference toward these mixed classes. We conducted a large‐scale survey to determine whether students who are technology ready would place higher utility on enrolling in mixed classes and/or whether there exists a participation bias such that students with low learning‐goal orientation place higher utility on enrolling in mixed classes. We found that overall students who are more technology ready do place higher utility on enrolling in mixed classes, but that learning‐goal orientation does not influence this decision. We conclude with implications and recommendations for business schools that are interested in offering mixed classes.
Sporotrichosis: Success of Itraconazole Treatment
Authors: Baroni Adone , Palla Marco , Iovene Maria Rosaria , Faccenda Franco , Aiello Francesco Saverio , Puca Rosa Valentina , Satriano Rocco Alfredo
Published: February 2007

An 82‐year‐old man with hypothyroidism presented with an ulcerated nodule on the dorsum of his left hand (Figure 1). The lesion had been present for about 3 months. Similar lesions were present along the lymphatic distribution of the dorsum of his left forearm, proximal to the first lesion, as well as the dorsum of his right forearm. Laboratory findings were normal. Immune complexes, complement 3, and complement 4 were negative. A biopsy from an ulcerated nodule was taken for both histologic examination and culture. Hematoxylin and eosin sections showed a nonspecific chronic granulomatous reaction. No fungi were detected by periodic acid‐Schiff stain and methenamine silver stain. Culture of tissue obtained from a skin biopsy of 1 lesion placed directly on Sabouraud agar produced colonies of Sporothrix schenckii (Figure 2). The diagnosis of lymphocutaneous sporotrichosis was confirmed.

Ulcerated nodules on the dorsum of the hand.

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Sporothrix culture (left); and under the electron microscope (right)

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Intraepithelial lymphocytes: their shared and divergent immunological behaviors in the small and large intestine
Authors: Kunisawa Jun , Takahashi Ichiro , Kiyono Hiroshi
Published: February 2007

Summary:  At the front line of the body‘s immunological defense system, the gastrointestinal tract faces a large number of food‐derived antigens, allergens, and nutrients, as well as commensal and pathogenic microorganisms. To maintain intestinal homeostasis, the gut immune system regulates two opposite immunological reactions: immune activation and quiescence. With their versatile immunological features, intraepithelial lymphocytes (IELs) play an important role in this regulation. IELs are mainly composed of T cells, but these T cells are immunologically distinct from peripheral T cells. Not only do IELs differ immunologically from peripheral T cells but they are also comprised of heterogeneous populations showing different phenotypes and immunological functions, as well as trafficking and developmental pathways. Though IELs in the small and large intestine share common features, they have also developed differences as they adjust to the two different environments. This review seeks to shed light on the immunological diversity of small and large intestinal IELs.
Generation of gut‐homing T cells and their localization to the small intestinal mucosa
Authors: Johansson‐Lindbom Bengt , Agace William W.
Published: February 2007

Summary:  The intestinal mucosa represents the largest body surface toward the external environment and harbors numerous T lymphocytes that take up resident within the intestinal epithelium or in the underlying lamina propria (LP). The intraepithelial lymphocytes include subsets of ‘unconventional’ T cells with unclear ontogeny and reactivity that localize to this site independently of antigen‐specific activation in secondary lymphoid organs. In contrast, the majority of the ‘conventional’ gut T cells are recruited into the intestinal mucosa subsequent to their activation in intestinal inductive sites, including Peyer’s patches (PPs) and mesenteric lymph nodes (MLNs). T cells homing to the small intestine express a distinct pattern of homing molecules, allowing them to interact with and transmigrate across intestinal postcapillary endothelium. At least some of these homing molecules, including the integrin α4β7 and the chemokine receptor CCR9, are induced on T cells during their activation in PPs or MLNs. Mucosal dendritic cells (DCs) play a key role in this process, but not all intestinal DCs possess the ability to confer a gut‐homing capacity to T cells. Instead, functionally specialized CD103+ DCs derived from the small intestinal LP appear to selectively regulate T‐cell homing to the small intestine.
Skin γδ T‐cell functions in homeostasis and wound healing
Authors: Jameson Julie , Havran Wendy L.
Published: February 2007

Summary:  There is a resident population of T cells found in murine skin that expresses an invariant Vγ3Vδ1 T‐cell receptor (TCR), and these cells are significantly different from lymphoid γδ T cells and αβ T cells in terms of ontogeny, tissue tropism, and antigen receptor diversity. These dendritic epidermal T cells are derived from fetal thymic precursor cells, are in constant contact with neighboring epidermal cells, and express a monoclonal γδTCR only found in the skin. Skin γδ T cells have been shown to play unique roles in tissue homeostasis and during tissue repair through local secretion of distinct growth factors including keratinocyte growth factors and insulin‐like growth factor‐1. In this review, we discuss evidence supporting a role for cross talk between skin γδ T cells and keratinocytes that contributes to the maintenance of normal skin and wound healing.
Epithelia: lymphocyte interactions in the gut
Authors: Dahan Stephanie , Roth‐Walter Franziska , Arnaboldi Paul , Agarwal Shradha , Mayer Lloyd
Published: February 2007

Summary:  The mucosal immune system is governed by a unique set of rules and regulations. The local microenvironment dictates the necessity for these differences. The intestinal epithelial cell (IEC) sits at the interface between an antigen‐rich lumen and a lymphocyte‐rich lamina propria (LP). The cross talk that occurs between these compartments serves to maintain intestinal homeostasis. IECs have the capacity to talk to LP lymphocytes, activating populations of unique regulatory T cells. These cells have the capacity to talk back to the epithelium, influencing epithelial cell growth and differentiation. This review looks at this cross talk and places it in the context of mucosal immunoregulation.
Thymic differentiation of TCRαβ+ CD8αα+ IELs
Authors: Lambolez Florence , Kronenberg Mitchell , Cheroutre Hilde
Published: February 2007

Summary:  Intraepithelial lymphocytes (IELs) contain several subsets, but the origin of the T‐cell receptor (TCR)αβ+ CD8αα+ IELs has been particularly controversial. Here we provide a synthesis, based on recent work, that attempts to unify the divergent views. The intestine has a primordial function in lymphopoiesis, and precursors with the potential to differentiate into T cells are found both in the epithelium and underlying lamina propria. Moreover, the thymus has been reported to export cells to the intestine that are not fully differentiated. TCRαβ+ CD8αα+ IELs can differentiate in the intestine from each of these sources, but in normal euthymic mice, the thymus appears to be the major source for TCRαβ+ CD8αα+ IELs. This unique IEL subset is a self‐reactive population that requires exposure to self‐agonists for selection in the thymus, similar to other regulatory T‐cell populations. IELs transition through a double‐positive (DP) intermediate in the thymus, but they originate from a subset of the DP cells that can be identified by its expression of CD8αα homodimers. The agonist‐selected cells in the thymus are TCRβ+ but CD4 and CD8 double negative. The evidence suggests that reacquired expression of CD8αα and downregulation of CD5 occur after thymus export, perhaps in the intestine under the influence of interleukin‐15. As a result of agonist exposure, a new gene expression program is activated. Therefore, the increased understanding of the developmental origin of TCRαβ+ CD8αα+ IELs may help us to understand how they participate in immune regulation and protection in the intestine.
Melatonin cycle in the fiddler crab Uca pugilator and influence of melatonin on limb regeneration
Authors: Tilden Andrea R. , Rasmussen Paul , Awantang Ruth M. , Furlan Scott , Goldstein Jessica , Palsgrove Michael , Sauer Angeline
Published: February 2007

Tilden AR, Rasmussen P, Awantang RM, Furlan S, Goldstein J, Palsgrove M, Sauer A. Melatonin cycle in the fiddler crab Uca pugilator and influence of melatonin on limb regeneration. J. Pineal Res. 1997; 23:142–147. © Munksgaard, Copenhagen

Melatonin was measured over 24 hr in the eyestalks of Uca pugilator by means of radioimmunoassay; crabs were acclimatized either to a LD 12:12 photoperiod or constant darkness. A significant peak occurred at 13.00 hr in the LD 12:12 crabs. A photophase peak in melatonin has only been reported in one other species, also a crustacean. In constant darkness, two melatonin peaks occurred, one at 16.00 hr and the other 12 hr later; these results suggest that the melatonin cycle is a true circadian rhythm. HPLC with ultraviolet‐visible detection was used to confirm the identity of melatonin immunoactivity. The influence of melatonin on regeneration of the walking legs was also examined: eyestalks were either removed or left intact, and limb bud length was measured every other day for at least 17 days in control and melatonin‐treated crabs (60 μg ml‐1 seawater). Melatonin significantly increased the rate of limb regeneration in both eyestalk‐intact and eyestalk‐removed groups; this is contrary to results of regeneration studies in other phyla, in which similar melatonin concentrations inhibited regeneration.
Quantitative research on skin pore widening using a stereoimage optical topometer and Sebutape®
Authors: Jo Ho Youn , Yu Dong Soo , Oh Chil Hwan
Published: February 2007

Background/aims: The treatment of skin pore widening is concerned with cosmetics sciences, but an objective and quantitative measurement method of the severity of skin pore widening has not been developed. In this study, bioengineering methods were applied to evaluate skin pore widening. The results from bioengineering measurements were compared with clinical visual assessment.

Methods: In order to quantify skin pore widening, three‐dimensional data of skin pore were produced by a stereoimage optical topometer (SOT). The sizes of follicular infundibulum were measured quantitatively, with reserved sebum by Sebutape®. 50 female volunteers were divided into two groups. Group A was tested by the cosmetics including active ingredient and group B by placebo. The constricting effect of skin pores by cosmetics was measured for immediate effect and long‐term effect.

Results: In the immediate effect, there was no statistical difference between groups A and B in visual scoring. In SOT, the size of the skin pores of group A had changed after application of cosmetics but there were no changes in group B. In the long‐term effect, there was no statistical difference between groups A and B in visual scoring. TA, TV, SA, and SV of skin pores of groups A and B were decreased in 3 and 6 months by SOT. In Sebutape® measurement, there was decreased volume of reserved sebum in groups A and B. The result of the Sebutape® study was similar to that of SOT.

Conclusion: Evaluation of skin pore change by visual assessment is difficult, but bioengineering tools are more reliable and useful methods for the assessment of skin pore change.
Functional analyses of the eyelid skin constituting the most soft and smooth area on the face: contribution of its remarkably large superficial corneocytes to effective water‐holding capacity of the stratum corneum
Authors: Pratchyapruit Walaiorn , Kikuchi Katsuko , Gritiyarangasan Pimonpun , Aiba Setsuya , Tagami Hachiro
Published: February 2007

Background/purpose: The eyelid constitutes a unique area on the face because of its soft, smooth and thin skin distinct from that of other facial portions. Its softness facilitates their easy compliance to blinking movement, which is indispensable to protect the wet surface of the eyeball. Moreover, the skin of the eyelid does not show any prominent follicular orifices or an oily appearance even in adults. Despite such uniqueness, its biophysical characteristics have remained unclear as compared with other facial skin.

Methods: We conducted non‐invasive instrumental measurements on the skin of the upper eyelid of 22 healthy Japanese adults in comparison with those of the adjacent facial skin, i.e. the cheek and nose. Additionally, we examined 10 adult patients with atopic dermatitis (AD) whose facial skin remained clinically free from skin lesions for at least 2 months.

Results: The eyelid skin showed high transepidermal water loss like other facial skin. Its skin surface hydration state was as high as that of the adjacent skin, despite the fact that the eyelid skin revealed extremely low amounts of surface lipids unlike its neighboring skin regions. However, in contrast to small corneocytes found in other facial areas, the corneocytes of the eyelid skin displayed a significantly larger surface size, suggesting that slow turnover of its stratum corneum (SC) takes place to allow sufficient maturation of the corneocytes, enabling them to exert efficient water‐binding capacity. Its pH tended to be higher than that of the adjacent skin. Its superficial blood flow was significantly higher than that of others, although skin color assessment showed lower color values for redness than those of the other facial skin sites. In clinically non‐lesional skin of adult AD patients, we found increased blood circulation and a higher parameter for redness, suggesting the presence of invisible mild inflammation in the dermis even long after subsidence of visible inflammatory changes.

Conclusion: Our present biophysical findings suggest that, although the eyelid skin is poor in surface lipids, its extraordinary large superficial corneocytes play an important role in maintaining sufficient hydration state of its skin surface to keep it soft and flexible, enabling its good compliance with the blinking movement.
Influence of skin colour on the detection of cutaneous erythema and tanning phenomena using reflectance spectrophotometry
Authors: Latreille Julie , Gardinier Sophie , Ambroisine Laurence , Mauger Emmanuelle , Tenenhaus Michel , Guéhenneux Sabine , Morizot Frédérique , Tschachler Erwin , Guinot Christiane
Published: February 2007

Background/purpose: This research aims at assessing the influence of baseline skin colour on the ability of reflectance spectrophotometry to detect cutaneous erythema induced by a low concentration of methyl nicotinate (2.5 mM) (first objective), and to detect tanning induced by ultraviolet rays (UVA+UVB) at infra‐erythemal doses (second objective).

Methods: Two independent studies were conducted to reach their respective objectives, on 27 women for the first study and on 12 women for the second study. Skin colour measurements were expressed in two different ways: percentages of reflected light at increasing wavelengths λ (400 nm<λ<700 nm, at 10 nm intervals), and chromametric coordinates of the CIELab 1976 system and individual typological angle (ITA°). Partial least squares discriminant analysis was performed to identify percentages of reflected light that allow the discrimination of the observations obtained after methyl nicotinate application from those obtained after water application (control). The same method was used for the discrimination of the measurements obtained after UV irradiation from those obtained before UV irradiation (control).

Results and discussion: The cutaneous erythema induced by a low concentration of methyl nicotinate was detected only in subjects with fair to very fair skin defined by ITA≥40°. The assumption is that in the darkest skins, the emitted light is mainly absorbed by the melanin in the epidermis. Otherwise, after UV irradiation, the tanning was detectable only for individuals with fair to dark skin defined by ITA <50°. This can be explained by the fact that UV stimulation of the fairest skin subjects, known to be melano‐compromised individuals, can only produce a weak tanning that our study did not succeed in detecting.
A cephalometric study on craniofacial morphology of Iranian children with beta‐thalassemia major
Authors: Amini F , Jafari A , Eslamian L , Sharifzadeh S
Published: February 2007

Structured abstract

Authors –  Amini F, Jafari A, Eslamian L, Sharifzadeh S

Objective –  To study cephalometric and facial features of Iranian children with beta‐thalassemia major.

Design –  Lateral cephalometric radiographs of thalassemic patients and controls who were matched for age, sex and ethnic origin were analyzed and compared.

Setting and Sample Population –  A total of 30 thalassemic patients (18 male and 12 females) from Aliasghar Hospital, and 30 controls from the Orthodontic Department of Azad University.

Outcome measure –  Size and shape differences in the craniofacial complex between thalassemic patients and controls.

Results –  All thalassemic patients had a Class II skeletal base relationship with an average ANB angle of 8.75°. There was no record of dramatic maxillary prognathism. However, the mandible of the thalassemic patients appeared to be smaller in size and more retruded in the face. A pronounced vertical growth direction was evident from angular and linear measurements. The dental deviations in thalassemic patients were mainly seen in the proclination and significant overeruption of incisors and increased overjet. Marked convex lower face and prominent upper and lower lips were evident from soft‐tissue measurements.

Conclusion –  Anemia does not only produce overgrowth of the maxilla. It also produces a retardation of condylar and ramal growth of the mandible producing Class II skeletal pattern.
Successful treatment of generalized eruptive histiocytoma with PUVA
Authors: Lan Ma H. , Metze Dieter , Luger Thomas A. , Steinhoff Martin
Published: February 2007

Generalized eruptive histiocytoma (GEH) is a rare benign skin disease mainly affecting adults which belongs to the family of non‐Langerhans‐cell histiocytoses. A 32‐year‐old Caucasian woman developed disseminated, monomorphic papules of the trunk after a common cold with sinusitis. Mucous membranes, palms and soles were spared. She also suffered from arthralgia without fever or night sweats. After one month, the patient noticed progression of the reddish papules involving the trunk, extremities and face. Clinical as well as histological examination and immunohistochemistry led to the diagnosis of GEH. The clinical examination and laboratory testing were normal, except for eosinophilia in the peripheral blood and bone marrow. No neoplastic diseases were found during thorough examinations. Systemic PUVA therapy produced rapid regression of the skin lesions. After 10 treatments the lesions began to regress leaving slight papules and multiple brown hyperpigmentations. The lesions resolved completely after 20 PUVA treatments. No relapses occurred. Systemic PUVA therapy represents a promising option for the treatment of GEH.
Deproteinized Bovine Bone Used as an Adjunct to Guided Bone Augmentation: An Experimental Study in the Rat
Authors: Stavropoulos Andreas , Kostopoulos Lambros , Mardas Nicolaos , Randel Nyengaard Jens , Karring Thorkild
Published: February 2007

Background: Promising results have been reported following treatment of periodontal and peri‐implant bone defects with deproteinized bovine bone grafts, but their influence on bone formation has not been clarified.

Purpose: The goal of this study was to examine whether implantation of deproteinized bovine bone (Bio‐Oss, Geistlich AG, Wolhusen, Switzerland) influences bone formation when used as an adjunct to guided bone augmentation (GBA).

Materials and Methods: A rigid, hemispherical, Teflon capsule was loosely packed with a standardized quantity of Bio‐Oss and placed with its open part facing the lateral surface of the mandibular ramus (test) in 30 rats. At the contralateral side of the jaw, an empty capsule was placed (control). Groups of 10 animals were sacrificed after 1, 2, and 4 months. The volumes of the space created by the capsule and of the (1) newly formed bone, (2) remaining Bio‐Oss particles, (3) soft connective tissue, and (4) acellular space in the capsule were estimated by a point‐counting technique in three or four histologie sections, taken by uniformly random sampling.

Results: Bone formation at 1 month was limited in both tests and controls. After 2 months, the mean volume of the newly formed bone occupied 9.0% of the space created by the capsule in the test specimens compared with 23.8% in the control specimens (p <.01). After 4 months, the respective figures were 11.6% (tests) versus 38.7% (controls) (p <.01).

Conclusion: It can be concluded that Bio‐Oss, used as an adjunct to GBA, interferes with bone formation.
Using vegetation indices derived from conventional digital cameras as selection criteria for wheat breeding in water‐limited environments
Authors: Casadesús J. , Kaya Y. , Bort J. , Nachit M. M. , Araus J. L. , Amor S , Ferrazzano G. , Maalouf F. , Maccaferri M. , Martos V. , Ouabbou H. , Villegas D.
Published: February 2007

The ability to assess green biomass is of particular interest in a number of wheat breeding environments. However, the measurement of this and similar traits is either tedious and time‐consuming or requires the use of expensive, sophisticated equipment, such as field‐based spectroradiometers to measure vegetation indices (VIs). Here, conventional digital cameras are proposed as affordable and easy‐to‐use tools for gathering field data in wheat breeding programmes. Using appropriate software, a large set of images can be automatically processed to calculate a number of VIs, based on the performance of simple colour operations on each picture. The purpose of this study was to identify a set of picture‐derived vegetation indices (picVIs) and to evaluate their performance in durum wheat trials growing under rainfed and supplementary irrigation conditions. Here, zenithal pictures of each plot were obtained roughly 2 weeks after anthesis, and the picVIs that were calculated were compared with the normalised difference vegetation index (NDVI), an index derived from spectroradiometrical measurements, and with the grain yield (GY) from the same plots. The picVIs that performed best were the Hue, CIE‐Lab a* and CIE‐Luv u* components of the average colour of each picture, the relative green area (GA) and the ‘greener area’, similar to GA but excluding the more yellowish‐green pixels. Our results showed a high correlation between all these picVIs and the NDVI. Moreover, in rainfed conditions, each picVI provided an estimation of GY similar to or slightly better than that provided by the NDVI. However, in irrigated conditions during anthesis, neither these picVIs nor the NDVI provided a good estimation of GY, apparently because of the saturation of the VI response in conditions of complete soil cover and high plant density.
Regional Planning in Queensland's Rangelands: Challenges and Prospects for Biodiversity Conservation
Authors: MCALPINE CLIVE A. , HEYENGA SONJA , TAYLOR BRUCE , PETERSON ANN , MCDONALD GEOFF
Published: February 2007

In Australia, the Commonwealth and State governments are increasingly devolving natural resource management (NRM) responsibilities to regional bodies. This move has led to the development of regional NRM plans. Native vegetation and biodiversity conservation, along with soil, pasture and water resources, are key components of the regional NRM plans in Queensland's extensive rangelands. This paper outlines and applies a set of criteria for evaluating the native vegetation and biodiversity content of accredited regional NRM plans for Queensland's rangelands. The evaluation showed considerable variation in the comprehensiveness of the information and knowledge base and management action targets among plans, including the poor articulation of impacts of excessive grazing pressure on biodiversity. The NRM plans lacked effective integration of natural resource, native vegetation and biodiversity conservation targets and actions. Several regions had too many biodiversity targets, many of which were poorly integrated. This is symptomatic of a limited understanding of rangelands as ecological systems and the lack of an integrated planning framework. We conclude regional NRM planning is not a ‘silver bullet’ for biodiversity conservation in the rangelands, but rather, it is the beginning of a long road to address complex, multi‐scale problems at a regional level.
The Parkes Elvis Revival Festival: Economic Development and Contested Place Identities in Rural Australia
Authors: BRENNAN‐HORLEY CHRIS , CONNELL JOHN , GIBSON CHRIS
Published: February 2007

This paper discusses the annual Elvis Revival Festival in the small town of Parkes, 350 km to the west of Sydney, in rural Australia. It explores the way in which a remote place with few economic prospects has created a tourism product, and subsequently captured national publicity, through a festival based around commemoration of the birthday of Elvis Presley, a performer who had never visited Australia, and certainly not Parkes. The Festival began in the early 1990s, when a keen Elvis fan rallied promoters (and other fans) around the idea of bringing Elvis impersonators to the town for an annual celebration. Since then, the Festival has grown in size, with notable economic impact. The town now partly trades on its association with Elvis, constituting an ‘invented’ tradition and place identity. Yet the festival is not without tensions. The images of Elvis and the traditions generated by the festival challenge those who wish to promote Parkes through more austere, staid notions of place and identity. For some, Elvis is a means for the town to generate income and national notoriety, while others prefer less ‘kitsch’ tourism attractions such as a nearby (and nationally famous) radio telescope. Results from interviews with key players and surveys of visitors demonstrate how ‘tradition’ is constructed in places (rather than being innate), and how small places, even in remote areas, can develop economic activities through festivals, and create new identities – albeit contested ones.
Dworkin's Theory of Law
Authors: Smith Dale
Published: February 2007

Ronald Dworkin is one of the most important, and one of the most controversial, contemporary legal philosophers. This article elucidates the main aspects of Dworkin's theory of law, discussing both his key criticisms of legal positivism and his own positive views about law. The article also briefly examines some of the major controversies surrounding Dworkin's theory of law, such as the debates arising out of his right answer thesis and semantic sting argument.
The Embodied Cognition Research Programme
Authors: Shapiro Larry
Published: February 2007

Embodied Cognition is an approach to cognition that departs from traditional cognitive science in its reluctance to conceive of cognition as computational and in its emphasis on the significance of an organism's body in how and what the organism thinks. Three lines of embodied cognition research are described and some thoughts on the future of embodied cognition offered.
Melanin coloration in New World orioles I: carotenoid masking and pigment dichromatism in the orchard oriole complex
Authors: M. Hofmann Christopher , J. McGraw Kevin , W. Cronin Thomas , E. Omland Kevin
Published: February 2007

Carotenoids produce the brilliant red, orange, and yellow colors of many animals. However, melanin pigments can also confer some of these same hues. Because carotenoid and melanin colors are produced in different ways and may serve different signaling functions, either within or between species, it is important to establish whether one or both types of pigment are responsible for coloration. We have discovered what appears to be an evolutionary switch from carotenoid‐ to melanin‐based color in two sexually dichromatic New World orioles. Using a combination of reflectance spectrometry and chromatographic analyses of plumage pigments, we found that the chestnut plumage of adult male orchard oriolesIcterus spuriusis produced predominantly by phaeomelanins. Orchard oriole feathers also contain carotenoids, which appear to be masked by the high concentration of phaeomelanins. In contrast, both carotenoids and phaeomelanins appear to contribute to color in adult male Fuertes's oriolesI. fuertesi. Moreover, yellow yearling male and female plumage in both species is produced by carotenoids alone. The masking of carotenoids with phaeomelanins in orchard orioles is interesting in light of the signaling roles that carotenoids are thought to play. In addition, these plumage differences produce a unique case of age and sexual pigment dimorphism in orchard and Fuertes's orioles.
Remodelling of action potential and intracellular calcium cycling dynamics during subacute myocardial infarction promotes ventricular arrhythmias in Langendorff‐perfused rabbit hearts
Authors: Chou Chung‐Chuan , Zhou Shengmei , Hayashi Hideki , Nihei Motoki , Liu Yen‐Bin , Wen Ming‐Shien , Yeh San‐Jou , Fishbein Michael C. , Weiss James N. , Lin Shien‐Fong , Wu Delon , Chen Peng‐Sheng
Published: February 2007

We hypothesize that remodelling of action potential and intracellular calcium (Cai) dynamics in the peri‐infarct zone contributes to ventricular arrhythmogenesis in the postmyocardial infarction setting. To test this hypothesis, we performed simultaneous optical mapping of Cai and membrane potential (Vm) in the left ventricle in 15 rabbit hearts with myocardial infarction for 1 week. Ventricular premature beats frequently originated from the peri‐infarct zone, and 37% showed elevation of Cai prior to Vm depolarization, suggesting reverse excitation–contraction coupling as their aetiology. During electrically induced ventricular fibrillation, the highest dominant frequency was in the peri‐infarct zone in 61 of 70 episodes. The site of highest dominant frequency had steeper action potential duration restitution and was more susceptible to pacing‐induced Cai alternans than sites remote from infarct. Wavebreaks during ventricular fibrillation tended to occur at sites of persistently elevated Cai. Infusion of propranolol flattened action potential duration restitution, reduced wavebreaks and converted ventricular fibrillation to ventricular tachycardia. We conclude that in the subacute phase of myocardial infarction, the peri‐infarct zone exhibits regions with steep action potential duration restitution slope and unstable Cai dynamics. These changes may promote ventricular extrasystoles and increase the incidence of wavebreaks during ventricular fibrillation. Whereas increased tissue heterogeneity after subacute myocardial infarction creates a highly arrhythmogenic substrate, dynamic action potential and Cai cycling remodelling also contribute to the initiation and maintenance of ventricular fibrillation in this setting.
Associative pairing enhances action potential back‐propagation in radial oblique branches of CA1 pyramidal neurons
Authors: Gasparini Sonia , Losonczy Attila , Chen Xixi , Johnston Daniel , Magee Jeffrey C.
Published: February 2007

Back‐propagating action potentials (bAPs) are involved in associative synaptic plasticity and the modulation of dendritic excitability. We have used high‐speed confocal and two‐photon imaging to measure calcium and voltage signals associated with action potential propagation into oblique branches of CA1 pyramidal neurons in adult hippocampal slices. The spatial profile of the bAP‐associated Ca2+ influx was biphasic, with an initial increase in the proximity of the branch point followed by a progressive decrease. Voltage imaging in the branches showed that bAP amplitude was initially constant and then steadily declined with distance from the soma. To determine the role of transient K+ channels in this profile, we used external Ba2+ (150 μm) as a channel blocker, after characterizing its effect on A‐type K+ channels in the apical trunk. Bath application of Ba2+ significantly reduced the A‐type K+ current in outside‐out patches and nearly eliminated the distance‐dependent decrease in bAP amplitude and its associated Ca2+ signal. Finally, small amplitude bAPs at more distal oblique branch locations could be boosted by simultaneous branch depolarization, such that the paired Ca2+ signal became nearly the same for proximal and distal oblique dendrites. These data suggest that dendritic K+ channels regulate the amplitude of bAPs to create a dendritic Ca2+ signal whose magnitude is inversely related to the electrotonic distance from the soma when bAPs are not associated with a significant amount of localized synaptic input. This distance‐dependent Ca2+ signal from bAPs, however, can be amplified and a strong associative signal is produced once the proper correlation between synaptic activation and AP output is achieved. We hypothesize that these two signals may be involved in the regulation of the expression and activity of dendritic voltage‐ and ligand‐gated ion channels.
Role of persistent sodium current in mouse preBötzinger Complex neurons and respiratory rhythm generation
Authors: Pace Ryland W. , Mackay Devin D. , Feldman Jack L. , Del Negro Christopher A.
Published: February 2007

Breathing movements in mammals depend on respiratory neurons in the preBötzinger Complex (preBötC), which comprise a rhythmic network and generate robust bursts that form the basis for inspiration. Persistent Na+current (INaP) is widespread in the preBötC and is hypothesized to play a critical role in rhythm generation because of its subthreshold activation and slow inactivation properties that putatively promote long‐lasting burst depolarizations. In neonatal mouse slice preparations that retain the preBötC and generate a respiratory‐related rhythm, we tested the role ofINaPwith multiple Na+channel antagonists: tetrodotoxin (TTX; 20 nm), riluzole (RIL; 10 μm), and the intracellular Na+channel antagonist QX‐314 (2 mm). Here we show thatINaPpromotes intraburst spiking in preBötC neurons but surprisingly does not contribute to the depolarization that underlies inspiratory bursts, i.e. the inspiratory drive potential. Local microinjection in the preBötC of 10 μmRIL or 20 nmTTX does not perturb respiratory frequency, even in the presence of bath‐applied 100 μmflufenamic acid (FFA), which attenuates a Ca2+‐activated non‐specific cation current (ICAN) that may also have burst‐generating functionality. These data contradict the hypothesis thatINaPin preBötC neurons is obligatory for rhythmogenesis. However, in the presence of FFA, local microinjection of 10 μmRIL in the raphe obscurus causes rhythm cessation, which suggests thatINaPregulates the excitability of neurons outside the preBötC, including serotonergic raphe neurons that project to, and help maintain, rhythmic preBötC function.
Apical GLUT2 and Cav1.3: regulation of rat intestinal glucose and calcium absorption
Authors: Morgan Emma L. , Mace Oliver J. , Affleck Julie , Kellett George L.
Published: February 2007

We have proposed a model of intestinal glucose absorption in which transport by SGLT1 induces rapid insertion and activation of GLUT2 in the apical membrane by a PKC βII‐dependent mechanism. Since PKC βII requires Ca2+ and glucose is depolarizing, we have investigated whether glucose absorption is regulated by the entry of dietary Ca2+ through Cav1.3 in the apical membrane. When rat jejunum was perfused with 75 mm glucose, Ca2+‐deplete conditions, or perfusion with the L‐type antagonists nifedipine and verapamil strongly diminished the phloretin‐sensitive apical GLUT2, but not the phloretin‐insensitive SGLT1 component of glucose absorption. Western blotting showed that in each case there was a significant decrease in apical GLUT2 level, but no change in SGLT1 level. Inhibition of apical GLUT2 absorption coincided with inhibition of unidirectional 45Ca2+ entry by nifedipine and verapamil. At 10 mm luminal Ca2+, 45Ca2+ absorption in the presence of 75 mm glucose was 2‐ to 3‐fold that in the presence of 75 mm mannitol. The glucose‐induced component was SGLT1‐dependent and nifedipine‐sensitive. RT‐PCR revealed the presence of Cavβ3 in jejunal mucosa; Western blotting and immunocytochemistry localized Cavβ3 to the apical membrane, together with Cav1.3. We conclude that in times of dietary sufficiency Cav1.3 may mediate a significant pathway of glucose‐stimulated Ca2+ entry into the body and that luminal supply of Ca2+ is necessary for GLUT2‐mediated glucose absorption. The integration of glucose and Ca2+ absorption represents a complex nutrient‐sensing system, which allows both absorptive pathways to be regulated rapidly and precisely to match dietary intake.
Recruitment of apical dendritic T‐type Ca2+ channels by backpropagating spikes underlies de novo intrinsic bursting in hippocampal epileptogenesis
Authors: Yaari Yoel , Yue Cuiyong , Su Hailing
Published: February 2007

A single episode of status epilepticus (SE) induced in rodents by the convulsant pilocarpine, produces, after a latent period of ≥ 2 weeks, a chronic epileptic condition. During the latent period of epileptogenesis, most CA1 pyramidal cells that normally fire in a regular pattern, acquire low‐threshold bursting behaviour, generating high‐frequency clusters of 3–5 spikes as their minimal response to depolarizing stimuli. Recruitment of a Ni2+‐ and amiloride‐sensitive T‐type Ca2+ current (ICaT), shown to be up‐regulated after SE, plays a critical role in burst generation in most cases. Several lines of evidence suggest that ICaT driving bursting is located in the apical dendrites. Thus, bursting was suppressed by focally applying Ni2+ to the apical dendrites, but not to the soma. It was also suppressed by applying either tetrodotoxin or the KV7/M‐type K+ channel agonist retigabine to the apical dendrites. Severing the distal apical dendrites ∼150 μm from the pyramidal layer also abolished this activity. Intradendritic recordings indicated that evoked bursts are associated with local Ni2+‐sensitive slow spikes. Blocking persistent Na+ current did not modify bursting in most cases. We conclude that SE‐induced increase in ICaT density in the apical dendrites facilitates their depolarization by the backpropagating somatic spike. The ICaT‐driven dendritic depolarization, in turn, spreads towards the soma, initiating another backpropagating spike, and so forth, thereby creating a spike burst. The early appearance and predominance of ICaT‐driven low‐threshold bursting in CA1 pyramidal cells that experienced SE most probably contribute to the emergence of abnormal network discharges and may also play a role in the circuitry reorganization associated with epileptogenesis.
Upregulation of AMPK during cold exposure occurs via distinct mechanisms in brown and white adipose tissue of the mouse
Authors: Mulligan Jacob D. , Gonzalez Asensio A. , Stewart Annette M. , Carey Hannah V. , Saupe Kurt W.
Published: February 2007

AMPK (adenosine monophosphate‐activated protein kinase), a key regulator of cellular energy metabolism and whole‐body energy balance, is present in brown adipose tissue but its role in regulating the acute metabolic state and chronic thermogenic potential of this metabolically unique tissue is unknown. To address this, the AMPK signalling system in brown and white adipose tissue was studied in C57Bl/6 mice under control conditions, during acute and chronic cold exposure, and during chronic adrenergic stimulation. In control mice AMPK activity in brown adipose tissue was higher than in any tissue yet reported (3‐fold the level in liver) secondary to a high level of expression of the α1 isoform. During the first day of cold, a time of intense non‐shivering thermogenesis, AMPK activity remained at basal levels. However, chronic (>7 days) cold caused a progressive increase in brown adipose tissue AMPK activity secondary to increased expression of the α1 isoform. To investigate the signalling pathway involved, noradrenaline (norepinephrine) and the β3‐adrenergic‐specific agonist CL 316, 243 were given for 14 days. This increased uncoupling protein‐1 content in brown adipose tissue, but not AMPK activity. In white adipose tissue 15 days of cold increased α1 AMPK activity 98 ± 20%, an effect reproduced by chronic noradrenaline or CL 316 243. We conclude that chronic cold not only increases AMPK activity in brown and white adipose tissue, but that it does so via distinct signalling pathways. Our data are consistent with AMPK acting primarily as a regulator of chronic thermogenic potential in brown adipose tissue, and not in the acute activation of non‐shivering thermogenesis.
Acoustic Excitation by Flow in T-Junctions
Authors: Ziada S. , Scott A. , Arthurs D.
Published: February 2007

The flow-acoustic nature of sharp-edged T-junctions is investigated experimentally. In this paper, the pipes forming the T-crossbar are referred to as the branches and the pipe forming the central stem of the T-shape is referred to as the main pipe. Four test cases are studied corresponding to: (a) T-junction with flow from each branch into the main pipe; (b) T-junction with flow from one branch into the main pipe, the other branch being closed; (c) T-junction with flow from the main pipe into the two branches, which is the reverse flow situation of the first case; and (d) T-junction with flow from the main pipe into one branch and the other branch is closed, which is the second case with reverse flow. It is found that the flow at the T-junction can excite the pipe acoustic modes to varying degrees, depending on the flow direction and piping configuration. For cases (c) and (d), the dimensionless pressure amplitude of the acoustic mode reaches a maximum at a Strouhal number similar to that of the turbulence broadband peak measured in the separation bubble downstream of the T-junction corner. Cases (a) and (b) exhibit a different type of flow-acoustic coupling. In both cases, the maximum acoustic pressure occurs at a Strouhal number which is different from that observed in the separation bubble. In addition, the pulsation amplitude is substantially stronger than that observed in cases (c) and (d). Detuning the branches weakens the resonance intensity, especially in case (c), which exhibits the strongest acoustic resonance.
Vibration Excitation Force Measurements in a Rotated Triangular Tube Bundle Subjected to Two-Phase Cross Flow
Authors: Zhang C. , Pettigrew M. J. , Mureithi N. W.
Published: February 2007

Two-phase cross flow exists in many shell-and-tube heat exchangers. Flow-induced vibration excitation forces can cause tube motion that will result in long-term fretting-wear or fatigue. Detailed vibration excitation force measurements in tube bundles subjected to two-phase cross flow are required to understand the underlying vibration excitation mechanisms. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures over a broad range of void fraction and mass fluxes. Both the dynamic lift and drag forces were measured with strain gage instrumented cylinders. The experiments revealed somewhat unexpected but significant quasi-periodic forces in both the drag and lift directions. The periodic forces appeared well correlated along the cylinder with the drag force somewhat better correlated than the lift forces. The periodic forces are also dependent on the position of the cylinder within the bundle.
Autofrettage and Reautofrettage of a Spherical Pressure Vessel
Authors: Parker A. P. , Huang X.
Published: February 2007

There is a numerical procedure for modeling autofrettage of thick-walled cylinders that incorporates the Bauschinger effect as a function of prior plastic strain and Von Mises’ yield criterion. In this paper the numerical procedure is extended to solve the analogous problem of a spherical, thick walled steel vessel. An equivalent new analytical solution for the case of a spherical vessel is also formulated. The analytical and numerical solutions are shown to be in close agreement. It is demonstrated numerically that a reautofrettage procedure, previously proposed for cylindrical vessels, may be extremely beneficial for spherical vessels. Additional commentary is provided on the limitations of certain analytic solutions.
Thermal Opening Technique for Nondestructive Evaluation of Closed Cracks
Authors: Tohmyoh Hironori , Saka Masumi , Kondo Yuichi
Published: February 2007

This paper describes the “thermal opening technique” for enhancing the ultrasonic response of a tightly closed crack. In this approach, thermal stress is generated by cooling the part locally to reduce the crack closure stress in stainless steel plate, which improves sensitivity to detect the scattering wave from the crack surface; this has however not been successful by the usual ultrasonic inspection technique without introducing the thermal stress. It has been observed that the enhancement of the scattering wave continues for several hours after removing the thermal stress. This valuable and unique characteristic of the scattering wave is related to the change in the contact condition between the mating crack surfaces. Finally, a method is proposed for the evaluation of the depth of tightly closed crack from the difference in the time-of-flight between the scattering wave and the corner echo. The quantitative characteristic of the method is also verified experimentally.
Rapid 20th-Century Increase in Coastal Upwelling off Northwest Africa
Authors: McGregor H. V. , Dima M. , Fischer H. W. , Mulitza S.
Published: February 2007

Near-shore waters along the northwest African margin are characterized by coastal upwelling and represent one of the world's major upwelling regions. Sea surface temperature (SST) records from Moroccan sediment cores, extending back 2500 years, reveal anomalous and unprecedented cooling during the 20th century, which is consistent with increased upwelling. Upwelling-driven SSTs also vary out of phase with millennial-scale changes in Northern Hemisphere temperature anomalies (NHTAs) and show relatively warm conditions during the Little Ice Age and relatively cool conditions during the Medieval Warm Period. Together, these results suggest that coastal upwelling varies with NHTAs and that upwelling off northwest Africa may continue to intensify as global warming and atmospheric CO
2
levels increase.
Thymine Dimerization in DNA Is an Ultrafast Photoreaction
Authors: Schreier Wolfgang J. , Schrader Tobias E. , Koller Florian O. , Gilch Peter , Crespo-Hernández Carlos E. , Swaminathan Vijay N. , Carell Thomas , Zinth Wolfgang , Kohler Bern
Published: February 2007

Femtosecond time-resolved infrared spectroscopy was used to study the formation of cyclobutane dimers in the all-thymine oligodeoxynucleotide (dT)
18
by ultraviolet light at 272 nanometers. The appearance of marker bands in the time-resolved spectra indicates that the dimers are fully formed ∼1 picosecond after ultraviolet excitation. The ultrafast appearance of this mutagenic photolesion points to an excited-state reaction that is approximately barrierless for bases that are properly oriented at the instant of light absorption. The low quantum yield of this photoreaction is proposed to result from infrequent conformational states in the unexcited polymer, revealing a strong link between conformation before light absorption and photodamage.