bluuebunny/crossref_metadata_2025 huggingface dataset:
Are Transient Increases in Blood Pressure During the Treadmill Stress Test Associated With Headache?
Authors: Thomaides T , Karapanayiotides T , Spantideas A , Andrikou A
Published: June 2006

We aimed to investigate whether transient increases in blood pressure (BP) are associated with headache, by provoking hypertension in 50 non-hypertensive cephalalgia sufferers (Ce), 50 hypertensive cephalalgia sufferers (HyCe) and 50 healthy subjects (C) with a treadmill stress test. Occurrence of headache among groups did not differ ( P = 0.81); however, women developed headache more frequently than men ( P < 0.0001). The 35 individuals who developed headache during the test compared with those who did not (regardless of their original group) had higher absolute diastolic BP and higher absolute and relative diastolic BP increase during the test ( P < 0.0001). HyCe patients that developed headache had higher diastolic BP than those that did not ( P < 0.002). For each group, the absolute/relative mean increases of systolic/diastolic BP did not differ between patients that developed headache and those that did not excepting relative diastolic BP increase in Ce (28± vs. 15±, P = 0.006). The appearance of headache during dynamic exercise is not associated with a history of headache or hypertension. In non-hypertensive cephalalgia sufferers, relative diastolic BP increases of >27± are associated with headache attacks whereas in HyCe sufferers absolute diastolic BP values may be more important.
Abnormal Modulatory Influence of Diffuse Noxious Inhibitory Controls in Migraine and Chronic Tension-Type Headache Patients
Authors: Sandrini G , Rossi P , Milanov I , Serrao M , Cecchini AP , Nappi G
Published: June 2006

The aim of this study was to evaluate the function of pain modulating systems subserving diffuse noxious inhibitory controls (DNICs) in primary headaches. DNICs were examined in 24 migraineurs, 17 patients with chronic tension-type headache (CTTH) and 20 healthy subjects by means of nociceptive flexion RIII reflex and the cold pressor test (CPT) as heterotopic noxious conditioning stimulation (HNCS). The subjective pain thresholds (Tp) and the RIII reflex threshold (Tr) were significantly lower in CTTH vs. controls. In controls a significant inhibition of the RIII reflex was observed during the CPT (-30±, P < 0.05). Conversely, migraine and CTTH patients showed facilitation (+31±, P < 0.05 and +40±, P < 0.01, respectively) of the RIII reflex during the HNCS. This study demonstrates a dysfunction in systems subserving DNICs in both migraine and CTTH. Impairment of endogenous supraspinal pain modulation systems may contribute to the development and/or maintenance of central sensitization in primary headaches.
Practitioner Review: Psychopharmacology in children and adolescents with mental retardation
Authors: Handen Benjamin L. , Gilchrist Richard
Published: June 2006

Background:  The use of psychotropic medication to treat children and adults with mental retardation (MR) has a long and extensive history. There are no identified medications to address specific cognitive deficits among persons with MR. Instead, psychotropic medications are used to treat specific behavioral symptoms and/or psychiatric syndromes. The purpose of this review is to provide an overview of the recent literature regarding the use of psychotropic medications in this population, focusing primarily on children and adolescents.

Methods:  The paper is divided into five general drug categories: psychostimulants, antipsychotics, antidepressants, mood stabilizers, and other drugs. Each section offers an overview of the research supporting the use of that class of medications in children and adolescents with MR as well as cautions regarding potential side effects. Finally, specific clinical recommendations are offered.

Results:  The majority of studies in MR tend to be open trials, case reports, or controlled studies with small samples. The available data suggests that persons with MR respond to various psychotropic medications in ways similar to the typically developing population. However, rates of response tend to be poorer and the occurrence of side effects tends to be more frequent.

Conclusions:  The use of psychotropic medications in children and adolescents with MR requires even greater monitoring and the use of lower doses and slower dosage increases than in the general population.
Distribution of PINK1 and LRRK2 in rat and mouse brain
Authors: Taymans Jean‐Marc , Van den Haute Chris , Baekelandt Veerle
Published: June 2006

Mutations in two kinases, PTEN induced kinase 1 (PINK1) and leucine‐rich repeat kinase 2 (LRRK2), have been shown to segregate with familial forms of Parkinson's disease. Although these two genes are expected to be involved in molecular mechanisms relevant to Parkinson's disease, their precise anatomical localization in mammalian brain is unknown. We have mapped the expression of PINK1 and LRRK2 mRNA in the rat and mouse brain via in situ hybridization histochemistry using riboprobes. We found that both genes are broadly expressed throughout the brain with similar neuroanatomical distribution in mouse compared to rat. PINK1 mRNA abundance was rather uniform throughout the different brain regions with expression in cortex, striatum, thalamus, brainstem and cerebellum. LRRK2, on the other hand, showed strong regional differences in expression levels with highest levels seen in the striatum, cortex and hippocampus. Weak LRRK2 expression was seen in the hypothalamus, olfactory bulb and substantia nigra. We confirmed these distributions for both genes using quantitative RT‐PCR and for LRRK2 by western immunoblot. As their broad expression patterns contrast with localized neuropathology in Parkinson's disease, the pathogenicity of clinical mutant forms of PINK1 and LRRK2 may be mediated by nigrostriatal‐specific mechanisms.
Cooperative action of glutamate transporters and cystine/glutamate antiporter system Xc– protects from oxidative glutamate toxicity
Authors: Lewerenz Jan , Klein Mathias , Methner Axel
Published: June 2006

Oxidative glutamate toxicity in the neuronal cell line HT22 is a model for cell death by oxidative stress. In this paradigm, an excess of extracellular glutamate blocks the glutamate/cystine‐antiporter system , depleting the cell of cysteine, a building block of the antioxidant glutathione. Loss of glutathione leads to the accumulation of reactive oxygen species and eventually cell death. We selected cells resistant to oxidative stress, which exhibit reduced glutamate‐induced glutathione depletion mediated by an increase in the antiporter subunit xCT and system activity. Cystine uptake was less sensitive to inhibition by glutamate and we hypothesized that glutamate import via excitatory amino acid transporters and immediate re‐export via system underlies this phenomenon. Inhibition of glutamate transporters by l‐trans‐pyrrolidine‐2,4‐dicarboxylic acid (PDC) and DL‐threo‐β‐benzyloxyaspartic acid (TBOA) exacerbated glutamate‐induced cell death. PDC decreased intracellular glutamate accumulation and exacerbated glutathione depletion in the presence of glutamate. Transient overexpression of xCT and the glutamate transporter EAAT3 cooperatively protected against glutamate. We conclude that EAATs support system to prevent glutathione depletion caused by high extracellular glutamate. This knowledge could be of use for the development of novel therapeutics aimed at diseases associated with depletion of glutathione like Parkinson's disease.
Involvement of the somatostatin‐2 receptor in the anti‐convulsant effect of angiotensin IV against pilocarpine‐induced limbic seizures in rats
Authors: Stragier Bart , Clinckers Ralph , Meurs Alfred , De Bundel Dimitri , Sarre Sophie , Ebinger Guy , Michotte Yvette , Smolders Ilse
Published: June 2006

The anti‐convulsant properties of angiotensin IV (Ang IV), an inhibitor of insulin‐regulated aminopeptidase (IRAP) and somatostatin‐14, a substrate of IRAP, were evaluated in the acute pilocarpine rat seizure model. Simultaneously, the neurochemical changes in the hippocampus were monitored usingin vivomicrodialysis. Intracerebroventricularly (i.c.v.) administered Ang IV or somatostatin‐14 caused a significant increase in the hippocampal extracellular dopamine and serotonin levels and protected rats against pilocarpine‐induced seizures. These effects of Ang IV were both blocked by concomitant i.c.v. administration of the somatostatin receptor‐2 antagonist cyanamid 154806. These results reveal a possible role for dopamine and serotonin in the anti‐convulsant effect of Ang IV and somatostatin‐14. Our study suggests that the ability of Ang IV to inhibit pilocarpine‐induced convulsions is dependent on somatostatin receptor‐2 activation, and is possibly mediated via the inhibition of IRAP resulting in an elevated concentration of somatostatin‐14 in the brain.
Potentiation of amphetamine‐mediated responses in caffeine‐sensitized rats involves modifications in A2Areceptors andzif‐268mRNAs in striatal neurons
Authors: Tronci Elisabetta , Simola Nicola , Carta Anna R. , De Luca M. Antonietta , Morelli Micaela
Published: June 2006

Subchronic intermittent administration of caffeine induces sensitization of motor behaviour and promotes cross‐sensitization to amphetamine motor activity. In order to evaluate the possible mechanisms at the basis of these effects, modifications in A2Areceptor andzif‐268mRNAs were evaluated in rats subchronically treated with caffeine (15 mg/kg i.p.) and challenged with caffeine (15 mg/kg i.p.) or amphetamine (0.5, 1 mg/kg s.c.) 3 days after discontinuation of treatment. Results showed that the sensitized motor response to caffeine was associated with a decrease of adenosine A2Areceptor andzif‐268mRNA levels in the striatum and nucleus accumbens, whereas cross‐sensitization to amphetamine was linked to a more pronounced increase ofzif‐268mRNA levels in the striatum, but not in the nucleus accumbens. Single‐cell analysis showed thatzif‐268mRNA modifications occurred in Enk(+) striatopallidal neurons after acute or subchronic treatment with caffeine and in Enk(–) striatonigral neurons after acute amphetamine administration. Potentiation of amphetamine effects was not associated with modifications of amphetamine‐induced dopamine release in nucleus accumbens in caffeine‐pretreated rats compared with vehicle‐pretreated rats. Results demonstrate that sensitization to caffeine and cross‐sensitization to amphetamine are associated with post‐synaptic neuroadaptive changes in selective neuronal populations of the striatum.
Chronic exposure to U18666A is associated with oxidative stress in cultured murine cortical neurons
Authors: Koh Chor Hui Vivien , Whiteman Matthew , Li Qiao‐Xin , Halliwell Barry , Jenner Andrew M. , Wong Boon Seng , Laughton Katrina M. , Wenk Markus , Masters Colin L. , Beart Philip M. , Bernard Ora , Cheung Nam Sang
Published: June 2006

Findings that antioxidant treatment may be beneficial in Alzheimer's disease indicate that oxidative stress is an important factor in its pathogenesis. Studies have also suggested that cholesterol imbalance in the brain might be related to the development of neurological disorders. Previously, we have reported that U18666A, a cholesterol transport‐inhibiting agent, leads to apoptosis and intracellular cholesterol accumulation in primary cortical neurons. In this study, we found that neuronal apoptosis mediated by U18666A is associated with oxidative stress in the treated cortical neurons. Cortical neurons treated with U18666A also showed decreased secretion and increased intraneuronal accumulation of β‐amyloid. The association of neuronal apoptosis with oxidative stress and Aβ accumulation may provide clues to the pathogenesis of Alzheimer's disease, as well as the role oxidative stress plays in other neurodegenerative diseases.
Youthful Muslim masculinities: gender and generational relations
Authors: Hopkins Peter E
Published: June 2006

There is evidence of two main discourses about the masculinities of young Muslim men – one that emphasizes patriarchy and aggression, the other effeminacy and academicism – and together they offer polarized perspectives of young Muslim men's masculinities. This paper explores youthful Muslim masculinities through narratives of gender and generational relations, using interview and focus group data collected during discussions with young Muslim men, mainly of Pakistani heritage, who live in Glasgow and Edinburgh, in Scotland. I seek to use this data to disrupt these dominant discourses by demonstrating that young Muslim men's masculinities are influenced by markers of social difference, as well as locality, and so are multiple, fluid and multi‐faceted.
Verrucous Hemangioma Revisited
Authors: Tennant Lucile B. , Mulliken John B. , Perez‐Atayde Antonio R. , Kozakewich Harry P. W.
Published: June 2006

Abstract:  We analyzed the clinical and histopathologic characteristics of verrucous hemangioma, compared these findings to hyperkeratotic mimickers such as capillary‐lymphatic malformation or capillary‐venous malformation and angiokeratoma circumscriptum, and reconsidered whether the term verrucous hemangioma is appropriate in the current nosology of vascular anomalies. Fourteen similar‐appearing localized hyperkeratotic vascular lesions were identified by one surgeon as either angiokeratoma, angiokeratoma circumscriptum, capillary‐venous malformation, capillary‐lymphatic malformation, or verrucous hemangioma. All lesions were located on an extremity, except for one lesion on the trunk, and were single or grouped and 2.6 to 8 cm in diameter. All were raised, red‐to‐purple, variably keratotic with irregular borders, and several manifested intermittent bleeding and oozing. Excision was performed at 4 months to 16 years of age. After histologic review, three lesions were designated as combined vascular malformations composed of capillaries, lymphatics, and veins, and none was designated as angiokeratoma. Eleven of 14 specimens met the histologic criteria for verrucous hemangioma: a hyperkeratotic epidermis with small, thick‐walled, blood‐filled vessels with multilamellated basement membrane involving the entire dermis as well as the subcutis. Immunostaining showed focal GLUT1 endothelial positivity (7/11) and low‐level MIB‐1 reactivity (8/11). Verrucous hemangioma has the accepted clinical features of vascular malformation, specifically presence at birth and proportionate growth. Microscopic features, such as thick vascular walls, multilamellated basement membrane, relatively uniform channel size, and GLUT1 immunopositivity are reminiscent of infantile hemangioma, particularly in its involutive phase. No firm conclusion seems possible as to whether verrucous hemangioma is a malformation or an indolent tumor, but clinical evidence favors the former category.
What is Standard of Care in the Evaluation of Elastosis Perforans Serpiginosa? A Survey of Pediatric Dermatologists
Authors: Vearrier David , Buka Robert L. , Roberts Brandie , Cunningham Bari B. , Eichenfield Lawrence F. , Friedlander Sheila F.
Published: June 2006

Abstract:  Elastosis perforans serpiginosa is a rare chronic dermatosis characterized by extrusion of altered elastic fibers through the epidermis. It often occurs in association with a variety of connective tissue disorders, and may develop following penicillamine therapy; however, it may also present without comorbidities. There are currently no well‐established protocols for the investigation of possible associated disorders in patients who present with elastosis perforans serpiginosa. We describe three patients with idiopathic elastosis perforans serpiginosa seen at our clinic and review the standard of care among 31 pediatric dermatologists surveyed who have cared for such a patient within the last 2 years. Based upon the results of our survey, we conclude that most pediatric dermatologists limit their evaluation of such patients to a thorough patient history and physical examination. This limited approach may be a sufficient evaluation in affected patients who are otherwise healthy.
Cutaneous Manifestations and Massive Genital Involvement in Hennekam Syndrome
Authors: Musumeci Maria Letizia , Nasca Maria Rita , De Pasquale Rocco , Schwartz Robert A. , Micali Giuseppe
Published: June 2006

Abstract:  We describe a 16‐year‐old boy with intestinal lymphangiectasia, lymphedema of the limbs and genitalia, mild mental retardation, and facial anomalies (Hennekam syndrome) and cutaneous lesions. Severe edema in the genital area created a gigantic mass that included the scrotum and penis. Numerous grouped red‐violaceous pseudo‐vesicular lesions and plaques, as well as verrucous brown papules, were present on the penis and scrotum. The prepuce was hypertrophic, with severe phimosis. Histologic analysis revealed dilated lymphatic vessels lined by a discontinuous layer of flat endothelial cells in the papillary dermis and extending down to the reticular dermis. Dilated blood vessels were also present but no cellular abnormalities were identified. A diagnosis of superficial cutaneous lymphatic malformations was made. To the best of our knowledge, this is the first detailed cutaneous histologic investigation in a patient with Hennekam syndrome. We assume that the onset of cutaneous lesions in our patient was likely triggered by a generalized worsening of his lymphedema.
Maturity‐Onset Diabetes of the Young with Necrobiosis Lipoidica and Granuloma Annulare
Authors: Marchetti Federico , Gerarduzzi Tania , Longo Filippo , Faleschini Elena , Ventura Alessandro , Tonini Giorgio
Published: June 2006

Abstract:  We describe a 12‐year‐old white girl with granuloma annulare localized to both ankles since she was five, necrobiosis lipoidica in the left pretibial region since she was ten, and a recent history of weakness, migraine, and weight loss. After initial evaluation, high fasting blood glucose levels and high hemoglobin A1c were found. The family history for non‐insulin‐dependent diabetes was suggestive of maturity‐onset diabetes of the young. Coexistence of necrobiosis lipoidica and granuloma annulare, together with a family history of non‐insulin‐dependent diabetes, the age of onset, and the absence of ketosis, are specific features making possible, a clinical diagnosis. Genetic confirmation may not be so easily accessible or necessary.
Double‐Blind, Randomized, Placebo‐Controlled Trial of the Use of Topical 10% Potassium Hydroxide Solution in the Treatment of Molluscum Contagiosum
Authors: Short Katherine A. , Fuller L. Claire , Higgins Elisabeth M.
Published: June 2006

Abstract:  Molluscum contagiosum is a common viral infection of the skin that frequently affects children. Lesions take between 6 and 18 months to resolve spontaneously and are a source of great embarrassment to both caretakers and children, often affecting attendance at school and limiting social activity. Treatment options to date have been poorly tolerated by children but recent studies have suggested that potassium hydroxide may be beneficial. This double‐blind, randomized, placebo‐controlled study compared 10% potassium hydroxide with placebo (normal saline). Twenty patients, aged 2 to 12 years, were recruited. Parents applied a solution twice daily to lesional skin until signs of inflammation appeared. Children were examined by the same observer on days 0, 15, 30, 60, and 90. Seventy percent of children receiving topical potassium hydroxide cleared, compared with 20% in the placebo group. Further dosing studies are required to identify whether weaker concentrations of potassium hydroxide are as efficacious, with less irritancy.
Entrepreneurs, Effectual Logic, and Over–Trust
Authors: Goel Sanjay , Karri Ranjan
Published: June 2006

This article complements extant literature on entrepreneurship and trust by proposing a model of over–trust (the tendency to trust more than what is warranted) using entrepreneurial characteristics and effectual logic. We trace how entrepreneurs following effectual processes may tend to over–trust. More formally, we propose that specific personality characteristics of the entrepreneur interact with effectual logic to make the entrepreneur more susceptible to over–trust. The proposed model is value neutral in that we do not imply that over–trust has negative consequences for entrepreneurs. In fact, it may be part of the overall risk that entrepreneurs assume in a new venture creation.
Trust within Entrepreneur Bank Relationships: Insights from Italy
Authors: Howorth Carole , Moro Andrea
Published: June 2006

Previous research has focused on economic factors that influence relationships between entrepreneurs and banks. Trust is relevant because it can reduce agency problems. A conceptual framework is developed from previous literature and from a study of entrepreneurs and bank managers from two regions of Northeast Italy. Testable propositions are derived regarding determinants of trust and the process of development in the entrepreneur–bank relationship. Within close–knit communities, information from third parties and community involvement affect the build up of trust. The implications are that bestowing trust may increase trustworthy behavior leading to a spiral of trust. Heavy monitoring may lead to lower levels of trust in a bank and lower demand for finance and/or less trustworthy behavior.
Government Agency and Trust in the Formation and Transformation of Interorganizational Entrepreneurial Networks
Authors: Neergaard Helle , Ulhøi John Parm
Published: June 2006

This article examines the role of trust and government agency in the creation and evolution of interorganizational cooperation among entrepreneurial ventures in general and the influence of trust on development trajectories in particular. The multiple–case approach used draws on five in–depth case studies adopting a focal firm perspective. Trust is shown to play a critical role in the formation, maintenance, and transformation of interorganizational cooperative relationships; whereas its absence results in discontinuation. Moreover, the results suggest that government agency may unintentionally destroy existing, well–functioning, interorganizational cooperative arrangements.
Razorfish
Authors: Forbes Daniel P. , Pavone Carla
Published: June 2006

Founded at the dawn of the Internet industry in 1995, Razorfish's pioneering technology, marketing, human resource, and acquisition strategies enabled it to become a paragon of global success in just 5 years. In 2000 and 2001, it appeared that this success would be short–lived. Increased competition, declining demand, and an economic recession all combined to threaten Razorfish's future. This case chronicles the rise of Razorfish and the Internet industry, as well as the challenges presented by a changing industry and economic context. In the spring of 2001, Razorfish management faced options that appeared as either high–risk or highly distasteful.
Phase‐Resolved Strain Measurements in Hydrated Ordinary Portland Cement Using Synchrotron X‐rays
Authors: Biernacki J. J. , Parnham C. J. , Watkins T. R. , Hubbard C. R. , Bai J.
Published: June 2006

X‐ray diffraction methods developed for the determination of residual stress states in crystalline materials have been applied to study residual strains and strains because of mechanical loading of ordinary portland cement paste. Synchrotron X‐rays were used to make in situ measurements of interplanar spacings in the calcium hydroxide (CH) phase of hydrated neat portland cement under uniaxial compression. The results indicate that strains on the order of 1/100 000 can be resolved providing an essentially new technique by which to measure the phase‐resolved meso‐scale mechanical behavior of cement under different loading conditions. Evaluation of these strain data in view of published elastic parameters for CH suggests that the CH carries a large fraction of the applied stress and that plastic interactions with the matrix are notable.
Conductivity and Permittivity of Nickel‐Nanoparticle‐Containing Ceramic Materials in the Vicinity of Percolation Threshold
Authors: Abdurakhmanov Umar , Sharipov Shamil , Rakhimova Yayra , Karabaeva Munira , Baydjanov Maksudbek
Published: June 2006

Conductivity and static permittivity of ceramic materials containing nanoparticles of Ni were measured in the vicinity of percolation threshold. It is found that, below this threshold, the experimentally obtained dependences of conductivity and static permittivity on the fractional Ni content in these materials are different from those calculated in the frame of the percolation theory. The origin of this discrepancy is discussed in terms of the network hierarchy model proposed recently by Balberg et al. for composite materials.
Microstructure and Surface Segregation of 3 mol% Y2O3‐Doped ZrO2 Particles
Authors: Ii Seiichiro , Yoshida Hidehiro , Matsui Koji , Ohmichi Nobukatsu , Ikuhara Yuichi
Published: June 2006

Microstructure of a commercial 3 mol% yttria‐doped zirconia nano‐particulate powder was observed by transmission electron microscopy, and the distribution of yttrium cation was investigated by energy‐dispersive X‐ray spectroscopy (EDS) with a probe size less than 1 nm. The cross‐sectional high‐resolution transmission electron microscopy observations revealed that there are two kinds of particles, consisting of single‐phase tetragonal and two phases comprising tetragonal and monoclinic. EDS analysis revealed that yttrium cations segregate to the surface of the tetragonal particle. The origin of tetragonal to monoclinic transformation was considered to be due to external stress during the powder milling process.
Effect of Friction on Inhomogeneous Shrinkage Behavior of Structured LTCC Tapes
Authors: Pohle Dirk , Wagner Matthias , Roosen Andreas
Published: June 2006

Vias, cavities, and other cutouts are significant inhomogeneities in low temperature co‐fired ceramics (LTCC) tapes and lead to inhomogeneous shrinkage during sintering, which has a negative effect on the quality of the final multilayer device. The influence of such cutouts on the shrinkage behavior of LTCC tapes was investigated by an exact measurement of the geometry before and after sintering and by in situ observations with an optical dilatometer. The investigations show a strong influence of cutouts on the magnitude of shrinkage inhomogeneities. This effect is more pronounced, if the tapes become thinner, the dimensions of the cutouts become larger, or their position becomes less centric. It is shown that the most important factor on the occurrence of shrinkage inhomogeneities in tapes with cutouts is the static friction of the LTCC material on the setter. Severe warpage is caused by interlocking effects, which occur at bumps of the rough setter surface when the inner edges of the cutouts are pulled over the setter. By using a separating agent between the LTCC tape and the setter, the static friction could be minimized, which eliminates the sintering inhomogeneities.
Microcontact Printed BaTiO3 and LaNiO3 Thin Films for Capacitors
Authors: Nagata Hajime , Ko Song Won , Hong Eunki , Randall Clive A. , Trolier‐McKinstry Susan , Pinceloup Pascal , Skamser Daniel , Randall Michael , Tajuddin Azizuddin
Published: June 2006

There is an ongoing need to develop new technologies to enable further down‐scaling of layer thicknesses in multilayer ceramic devices, for example, in multilayer capacitors (MLC). Microcontact printing of chemical solutions of both the dielectric and electrode layers was explored as an economical means of preparing patterned thin films for MLC without requiring photolithography. For this purpose, methanol/acetic acid‐based BaTiO3 solutions were spun onto polydimethylsiloxane stamps, printed onto substrates, pyrolyzed, and crystallized. LaNiO3 was used as a prototype electrode that could also be microcontact printed. The line edge roughness produced this way was on the order of a tenth of a micrometer, which should enable very small margins. The printed layer thickness was also very uniform. Microcontact printed capacitors with a single dielectric layer were fabricated and found to have dielectric constants >800 with loss tangents <2%. Alignment between subsequent layers is readily achieved. Multilayer dielectric/electrode stacks could be fabricated without cracking or delaminations. Consequently, microcontact printing appears to be a viable potential means of preparing MLC with layer thicknesses in the range of ≤0.2 μm.
Oviposition preference and larval performance in the exotic birch‐leafmining sawfly Profenusa thomsoni
Authors: Digweed Scott C.
Published: June 2006

This study used experiments at several spatial scales to determine whether (1) intraspecific competition occurs among larvae of the leafmining sawfly Profenusa thomsoni (Konow) (Hymenoptera: Tenthredinidae) on birch (Betula spp.), (2) oviposition site preferences of P. thomsoni maximize offspring performance, and (3) early‐season damage by external folivores or the leafminer Fenusa pumila Leach (Hymenoptera: Tenthredinidae) affects oviposition preferences or larval performance of P. thomsoni.

Larval P. thomsoni competed at natural densities; survival and weight of larvae were reduced under crowded conditions. Despite this, females of P. thomsoni tended to lay eggs on leaves already bearing eggs from other females and discriminated only weakly among leaves of different sizes on a branch. Both damage by F. pumila and artificial damage to leaves early in the season decreased survival of P. thomsoni larvae on the same branch, and ovipositing P. thomsoni females avoided damaged leaves but not other leaves on the same branch. In general, oviposition choices by P. thomsoni reduced larval survival. Possible reasons for the lack of a strong preference–performance relationship in P. thomsoni are discussed.
Influence of postzygotic reproductive isolation on the interspecific transmission of the paternal sex ratio chromosome inTrichogramma
Authors: Jeong Gilsang , Stouthamer Richard
Published: June 2006

The paternal sex ratio (PSR) chromosome is a supernumerary chromosome that causes the destruction of the paternal chromosome set in the first mitosis in a fertilized egg. It is known from parasitoid wasps in the generaNasoniaandTrichogramma(Hymenoptera). In these haplodiploids, the egg fertilized by sperm carrying PSR matures as a haploid male that again carries, and is capable of transmitting, the PSR chromosome. Because of its unique transmission behavior, the PSR chromosome may be easily transmitted between species. This study tests whether the interspecific transmission of PSR betweenTrichogramma kaykaiPinto and Stouthamer andTrichogramma deionPinto and Oatman (Hymenoptera: Trichogrammatidae) is affected by two types of postzygotic reproductive isolation, i.e., hybrid inviability and hybrid sterility. The results show that PSR can rescue fertilized eggs that would normally be inviable in the interspecific cross and the rescued eggs develop into male offspring that carry PSR. The results suggest that the two types of postzygotic reproductive isolation have no effect on the transmission of PSR between the twoTrichogrammaspecies.
Behavioural responses of the aphid parasitoid Diaeretiella rapae to volatiles from Arabidopsis thaliana induced by Myzus persicae
Authors: Girling R.D. , Hassall M. , Turner J.G. , Poppy G.M.
Published: June 2006

In response to herbivory by insects, several plant species have been shown to produce volatiles that attract the natural enemies of those herbivores. Using a Y‐tube olfactometer, we investigated responses of the aphid parasitoid Diaeretiella rapae MacIntosh (Hymenoptera: Aphidiidae) to volatiles from Arabidopsis thaliana Columbia (Brassicaceae) plants that were either undamaged, infested by the peach‐potato aphid, Myzus persicae Sulzer (Homoptera: Aphididae), or mechanically damaged, as well as to volatiles from just the aphid or its honeydew. In dual‐choice experiments, female D. rapae given oviposition experience on A. thaliana infested with M. persicae were significantly attracted to volatiles from A. thaliana infested with M. persicae over volatiles from undamaged A. thaliana and similarly were significantly attracted to plants that had been previously infested by M. persicae, but from which the aphids were removed, over undamaged plants. Diaeretiella rapae did not respond to volatiles from M. persicae alone, their honeydew, or plants mechanically damaged with either a pin or scissors. We conclude that an interaction between the plant and the aphid induces A. thaliana to produce volatiles, which D. rapae can learn and respond to. Poor responses of D. rapae to volatiles from an A. thaliana plant that had two leaves infested with M. persicae, with the two infested leaves being removed before testing, suggested the possibility that, at this stage of infestation, the majority of volatile production induced by M. persicae may be localized to the infested tissues of the plant. We conclude that this tritrophic interaction is a suitable model system for future investigations of the biochemical pathways involved in the production of aphid‐induced volatiles attractive to natural enemies.
X‐ray computerized tomography as a new method for monitoring Amegilla holmesi nest structures, nesting behaviour, and adult female activity
Authors: Greco Mark , Bell Melissa , Spooner‐Hart Robert , Holford Paul
Published: June 2006

Nest structures of the Australian blue‐banded bee, Amegilla holmesi Rayment (Hymenoptera: Apidae), are difficult to monitor non‐invasively, because the bee is a fossorial species that constructs tunnels and natal cells within the soil. Visualization of nest structures requires physical separation of the structures from the soil substrate, which destroys the nest. Using helical, two‐dimensional (2D) X‐ray computerized tomography (CT), and three–dimensional (3D) volume rendering software on 13 artificial mud‐brick nests, we were able to view all previously reported nest structures and cell contents without damaging the nests. We used three volume rendering algorithms (sum along ray, scatter HQ, and false colour), two of which (scatter HQ and false colour) have not previously been used to visualize nest architecture. Each algorithm has a particular advantage for visualizing specific nest structures. The 2D CT images provided the greatest spatial resolution within and between nest structures (capture pixel matrix size 512 × 512; voxel size 0.449 mm3), and for the first time we were able to visualize a meniscus within natal cells that contained liquid provisions, which is a valuable characteristic in detecting the earliest stage of juvenile development once a natal cell is sealed. We also recorded and attributed Hounsfield units to nest structures and their contents that can be utilized in future studies. This new method also enabled us to count and measure natal cells using on‐screen linear callipers, visually observe and record stages of larval and pupal development, and visually gauge the incidence of cell parasitism without damaging the nest. Artificial nests can be transported easily to research facilities that have CT scanners; each scan including image processing takes less than 30 min per nest and currently costs less than AUD 20.00, which is within the reach of apiculturists. X‐ray CT could be used to follow the life cycle of blue‐banded bees and other cryptic species and also to monitor their health.
Disarming the paradox of sublethal plant defense against insects: Trirhabda virgata larval development time and leaf tissue loss on Solidago altissima
Authors: Wise Michael J. , Fox Rebecca J. , Abrahamson Warren G.
Published: June 2006

Although the fitness benefits of traits that kill herbivores are obvious, the contention that sublethal antiperformance traits have evolved as plant defenses has proved more controversial. Traits that slow herbivore development seem particularly paradoxical, given the common assumption that a protracted feeding period will lead to greater total consumption. Whereas this assumption is superficially reasonable, there is very little evolutionarily relevant evidence to suggest that plants on which larval development is slower actually lose more tissue. For the assumption underlying the sublethal‐defense paradox to be valid, plant traits that affect larval development time and tissue loss must be positively correlated genetically within natural plant populations. In this study, we examined the relationship between larval development time of the beetle Trirhabda virgata LeConte (Coleoptera: Chrysomelidae) and plant tissue loss by its host plant Solidago altissima L. (Asteraceae). Plant genets on which the larval development time was longer ended up losing less leaf area than plant genets that allowed quicker larval development. This negative genetic correlation contradicts the common assumption that greater sublethal resistance leads to increased tissue loss. Combined with other hypothesized benefits of sublethal resistance, this result suggests that antiperformance traits may constitute a more potent form of resistance than is generally acknowledged.
AGE STRUCTURE AND GROWTH OF THE BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) FROM STRANDINGS IN THE MISSISSIPPI SOUND REGION OF THE NORTH‐CENTRAL GULF OF MEXICO FROM 1986 TO 2003
Authors: Mattson Megan Cope , Mullin Keith D. , Ingram G. Walter , Hoggard Wayne
Published: June 2006

Abstract

Despite their high abundance and wide distribution, little is known about the historical or current growth and age structure of coastal bottlenose dolphins (Tursiops truncatus) in the north‐central Gulf of Mexico. Between 1986 and 2003, teeth were collected from bottlenose dolphins stranded on the mainland coast of Mississippi and the adjacent barrier islands. Bottlenose dolphin strandings occurred year round, peaking in March and April. Neonate strandings also peaked during these 2 mo. Age estimates were obtained from 111 animals by reading the growth layer groups in the dentine layer of the teeth. The ages ranged from <1 yr to 30 yr of age. The two‐stage Laird–Gompertz growth model was fitted to the total length and age data. On the basis of this model, the asymptotic lengths were estimated at 250 cm for females and 255 cm for males. The length at birth estimates were 98–103 cm for females and 100–107 cm for males. These lengths are similar to those of bottlenose dolphin populations from other Gulf of Mexico areas and from the North Atlantic Ocean along the southeastern United States.
Large‐scale spatial and temporal patterns in population dynamics of the stoat, Mustela erminea, and the least weasel, M. nivalis, in Finland
Authors: Hellstedt Paavo , Sundell Janne , Helle Pekka , Henttonen Heikki
Published: June 2006

The stoat and the least weasel are specialist predators of small rodents, and therefore their numbers are likely to depend on the availability of voles. These small predators are ecologically alike, but they differ somewhat in their diet. The stoat is larger in size than the least weasel and therefore capable of using a wider variety of prey species, while the least weasel is more restricted to small mammals. Voles in northern Fennoscandia exhibit cyclic dynamics of 3–5 years with large‐scale spatial synchrony and geographical trends in cycle length and amplitude. We predicted that the cyclic dynamics of voles are reflected in the dynamics of their predators with slight differences between the stoat and the least weasel. In this study we use snow‐tracking data to characterize the dynamics of small mustelids. The data were collected from different parts of Finland using permanent triangle‐shaped census routes of 12 km in 1989 to 2003. Population fluctuations of small mustelids were generally multiannually periodic and in synchrony over large areas, but we did not find any clear geographical gradient in the attribute of small mustelid dynamics comparable to those observed in vole population fluctuations. Instead, we found a similar decreasing temporal trend in the abundances of both species as has been recently reported for voles.
Environmental variability influences the structure of benthic algal communities in an oligotrophic lake
Authors: Kathleen McCabe Shelley , Cyr Hélène
Published: June 2006

Theoretical models suggest that environmental variability can promote biodiversity, both in terms of richness and evenness of species. These findings have been supported experimentally in simplified communities with simplified regimes of environmental variability. Here we test the importance of environmental variability in a more natural setting by comparing the composition of benthic algal communities along a natural gradient of environmental variability created by internal waves in an elongated lake basin. Algal communities were grown on tiles at five upwind and five downwind sites in the lower littoral zone of South Arm, in Lake Opeongo, Ontario, Canada. Upwind sites were 1°C colder, on average, than downwind sites and had more variable water temperatures. The ranges of mean water temperatures and of water temperature variability were greater among upwind sites than among downwind sites. We used water temperature variability as a proxy for environmental variability. Total algal biovolume was similar at all sites, but the composition of these communities varied systematically with temperature variability. An observed shift in the relative dominance between Achnanthidium minutissimum, Surirella sp. and Pinnularia spp. is consistent with what we know about these species. Diatom richness increased from 12 to 15 genera with increasing variability at upwind (p=0.10, r2=0.65) and downwind sites (p=0.11, r2=0.63). Community evenness also increased with increasing variability (p=0.03, r2=0.82 at upwind sites; p=0.0002, r2=0.99 at downwind sites). These relationships were observed despite low nutrient and light availability, as well as the presence of grazers. Furthermore, environmental variability affected diatom communities in the presence of several competing factors (temperature, light, nutrients and disturbance). Our results suggest that increased environmental variability can lead to higher biodiversity in a complex natural system.
Physiological responses to stoichiometric constraints: nutrient limitation and compensatory feeding in a freshwater snail
Authors: Fink Patrick , Von Elert Eric
Published: June 2006

Nitrogen (N) and phosphorus (P) are considered to be essential nutrients that control secondary production in various ecosystems; insufficient availability of N and P can limit herbivore growth. Here, data are presented from field samplings and from a laboratory experiment on the potential of primary producers low in P, N, or P and N to constrain growth of the freshwater gastropod Radix ovata. The filamentous green alga Ulothrix fimbriata was cultured under different nutrient regimes, resulting in algae with different C:N:P ratios. The pure algae were fed in high and low quantities to juvenile R. ovata. Low availability of N and especially P in the algae strongly constrained the biomass accrual of the herbivore. In accordance with theoretical predictions, these food quality differences were highly dependent on the food quantity. The snails’ growth rate was significantly related to their body C:P ratio, thereby supporting the growth rate hypothesis. R. ovata displayed a pronounced compensatory feeding response to low‐nutrient food that could partly dampen but not fully compensate the food quality effects on snail growth. Increased feeding of gastropods at low P and/or N availability leads to depletion of periphyton biomass; hence compensatory feeding would shift the benthic herbivore community from a P or N limitation to a C limitation and thus have whole‐ecosystem effects.
Size and temperature dependent foraging capacities and metabolism: consequences for winter starvation mortality in fish
Authors: Byström Pär , Andersson Jens , Kiessling Anders , Eriksson Lars‐Ove
Published: June 2006

The foraging related capacities, energy requirements and the ability of individuals to withstand starvation are strongly dependent on body size and temperature. In this study, we estimated size‐dependent foraging rates and critical resource density (CRD) in small Arctic char (Salvelinus alpinus) under winter conditions and compared these with previous observations under summer conditions. We investigated if starvation mortality is size‐dependent in the laboratory, and we assessed the potential for winter growth and the occurrence and size dependency of winter mortality both in a large scale pond experiment and in natural lakes. The efficiency of foraging on macroinvertebrates increased with size but was lower at 4 than 12°C, still CRD was lower at 4 than 12°C as metabolic rates decreased faster than foraging efficiency with temperature. When starved, small char died before large and at rates which suggest that YOY char need to feed during winter to avoid starvation. Results from both our pond experiment and field study indicate that survival of YOY char over winter is high, despite severe winter conditions, because YOY char are able to feed and grow during winter. In seasonal environments with declining resources, the size scaling and temperature dependency of foraging and metabolic demands may provide conditions which can favour either small or large individuals. This size advantage dichotomy relates to that larger individual's by having a higher CRD are more likely to start starving, but once resource levels are below CRD for all size classes, small individuals starve to death at a higher rate. Negative size‐dependent winter mortality from starvation is suggested to be more pronounced in species that are not adapted to feed at low temperatures and in species feeding on zooplankton, since zooplankton abundance, in contrast to macroinvertebrate abundance, is generally low during winter.
Age differences in blue tit Parus caeruleus plumage colour: within‐individual changes or colour‐biased survival?
Authors: Delhey Kaspar , Kempenaers Bart
Published: June 2006

In many species of passerine birds yearlings display a less elaborate version of the adult secondary sexual traits, but the causes of such differences in ornamentation are not always well understood. We studied age‐related changes in blue tit Parus caeruleus UV/blue structural crown coloration, a sexually selected trait. In our Austrian study population, older blue tits, irrespective of sex, displayed on average a more ultraviolet (lower hue, higher UV chroma), more chromatic and brighter crown coloration than yearlings. This age dichromatism was caused by within‐individual changes in the expression of crown coloration between years since males and females became more UV, more chromatic and brighter as they aged. Colour biased survival did not contribute to the observed pattern of age dichromatism since crown coloration was largely unrelated to overwinter survival. Between‐year repeatability of crown colour was significant for most colour variables but low in general, and lower for females than for males. In the blue tit, yearling males might benefit from being less ornamented by avoiding adult aggression but at the expense of sexual attractiveness. Adaptive explanations of blue tit age dichromatism should however take into account that age effects were of similar magnitude in males and females. This suggests that both male and female yearlings could benefit from being less ornamented and hence that sexual selection might be acting on both sexes simultaneously in this species.