bluuebunny/crossref_metadata_2025 huggingface dataset:
Body mass change strategies in blackbirds Turdus merula: the starvation–predation risk trade‐off
Authors: MACLEOD R. , BARNETT P. , CLARK J. A. , CRESSWELL W.
Published: March 2005

It is theoretically well established that body mass in birds is the consequence of a trade‐off between starvation risk and predation risk. There are, however, no studies of mass variation from sufficiently large wild populations to model in detail the range of diurnal and seasonal mass change patterns in natural populations and how these are linked to the complex environmental and biological variables that may affect the trade‐off.

This study used data on 17 000 individual blackbirds Turdus merula to model how mass changes diurnally and seasonally over the whole year and over a wide geographical area. Mass change was modelled in respect of temperature, rainfall, day length, geographical location, time of day and time of year and the results show how these mass changes vary with individual size, age and sex.

The hypothesis that seasonal mass is optimized over the year and changes in line with predictors of foraging uncertainty was tested. As theory predicts, reduced day length and reduced temperature result in increased mass and the expected seasonal peak of mass in midwinter.

The hypothesis that diurnal mass gain is optimized in terms of starvation–predation risk trade‐off theory was also tested. The results provide the first empirical evidence for intraspecies seasonal changes in diurnal mass gain patterns. These changes are consistent with shifts in the relative importance of starvation risk and predation risk and with the theory of mass‐dependent predation risk.

In winter most mass was gained in the morning, consistent with reducing starvation risk. In contrast, during the August–November non‐breeding period a bimodal pattern of mass gain, with increases just after dawn and before dusk, was adopted and the majority of mass gain occurred at the end of the day consistent with reducing mass‐dependent predation risk. The bimodal diurnal mass gain pattern described here is the first evidence that bird species in the wild gain mass in this theoretically predicted pattern.
Phenotypic plasticity in a maternal trait in red deer
Authors: NUSSEY DANIEL H. , CLUTTON‐BROCK TIM H. , ELSTON DAVID A. , ALBON STEVE D. , KRUUK LOESKE E. B.
Published: March 2005

Phenotypic plasticity and microevolution represent the two processes by which phenotypic traits in a population can track environmental change. While there is a growing literature documenting microevolution in reproductive traits in naturally occurring animal populations, few studies to date have examined either between‐individual variation in levels of plasticity or how selection acts on plasticity.

We present here mixed‐effect linear models analysing changes in calving date in relation to autumn rainfall observed over a 30‐year study of 2147 red deer on the Isle of Rum, Scotland. The study period is characterized by a phase of low and rising population density (up to and including 1980), followed by a phase of high and fluctuating population density (1981 to present).

Variation within individual females explained a population‐level trend of delayed calving dates following years of high autumn rainfall. There was significant variation between females both in their average calving dates and in their individual plastic responses of calving date to autumn rainfall.

Females born in the low population density phase were, on average, phenotypically plastic for the calving date–autumn rainfall relationship, and showed significant variation in plasticity. Selection favoured individuals with early average calving dates among these females.

Among females born at high population density, there was on average no significant plasticity for calving date, but variation in plastic responses was still present. Selection favoured females with increasingly positive plastic responses of calving date to autumn rainfall.

We argue that early experience of high population density affects the physiological condition of females, making an environmental response (calving early following dry autumns) in later life physiologically untenable for all but a few high quality individuals. These same few individuals also tend to be fitter and have higher reproductive success.
Effect of luxation type on pulpal blood flow measurements: a long‐term follow‐up of luxated permanent maxillary incisors
Authors: STROBL H. , MOSCHEN I. , EMSHOFF I. , EMSHOFF R.
Published: March 2005

summary  Laser Doppler flowmetry (LDF) is a non‐invasive method to assess pulpal blood‐flow (PBF). Dental injury has been associated with significant PBF reduction. The purpose of this study was to assess whether (i) the type of luxation trauma may affect PBF measurements and (ii) whether luxation type‐related measurements may show short‐ and long‐term changes of PBF values. In 41 trauma patients, 69 maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units were recorded in four sessions, on the day of splint removal, and 12, 24 and 36 weeks after splint removal. Statistical analysis consisted of univariate analysis of variance for repeated measurements. For the LDF measurements, the main effect of the variable ‘session’ was not significant (P = 0·119). However, there was a significant ‘session’/‘luxation type’ interaction (P = 0·000). Analysis of simple session‐within‐luxation type effects revealed intrusive luxations to be associated with a significant decrease in PBF values (P = 0·000), while subluxations (P = 0·568), lateral luxations (P = 0·980), extrusive luxations (P = 0·910), and avulsions (P = 0·996) showed no significant difference between session‐related values. The PBF measurements did not change over time for the contralateral incisors (P = 0·996). The LDF may become useful in the detection of pulpal ischaemic episodes in luxated maxillary incisors after repositioning and splinting. Further studies are warranted to assess the validity of the diagnosis of post‐traumatic ‘ischaemic episodes’ by comparing it with histological tooth pulp changes, and by determining how well it may predict course and response to treatments in clinical trials.
Postnatal euphoria: are ‘the highs’ an indicator of bipolarity?
Authors: Heron Jessica , Craddock Nick , Jones Ian
Published: March 2005

Research into postnatal mood disorders to date has concentrated on depressive syndromes of varying severity and full‐blown acute puerperal mania. However, clinical experience, backed up by a review of the literature, indicates that milder hypomanic symptoms also occur in the early puerperium. Although these symptoms may often be regarded as clinically insignificant, there is evidence that the experience of minor puerperal elation may be a predictor of later postpartum depression. In addition, studying mild puerperal high mood may provide insights into the pathophysiology of more severe puerperal mania and psychosis. This paper critically reviews the literature on milder forms of high mood occurring in the puerperium and discusses the potential clinical and research significance of ‘the highs’.
Assessment tools for screening and monitoring bipolar disorder
Authors: Baldassano Claudia F
Published: March 2005

Objective:  To review the availability and suitability of tools for screening, diagnosing, and monitoring people with bipolar disorder in both psychiatric and general practice.

Methods:  Currently available assessment tools suitable for use with patients with bipolar disorder were identified through a MEDLINE search using the following key terms: bipolar, screening, diagnosis, monitoring. Only peer‐reviewed papers published in English were considered for further review.

Results:  A review of the current literature revealed a small number of published and appropriately validated clinical tools suitable for the assessment of bipolar disorder in terms of screening, diagnosis, and long‐term monitoring.

Conclusions:  While there are a large number of formal rating scales for the assessment of various clinical aspects of bipolar spectrum disorders, there are currently only a limited number of assessment tools well suited for use in routine clinical practice. Widespread use of brief, clinically validated, and easy to use screening tools could facilitate the early identification of patients with bipolar spectrum disorders. A less structured diagnostic approach should facilitate diagnosis of the more subtle forms of the disease, particularly bipolar II disorder. Long‐term monitoring tools should strengthen the therapeutic alliance between the patient and clinician and improve long‐term quality of care and assessment of outcomes.
Patient perspectives on the diagnosis, treatment, and management of bipolar disorder
Authors: Lewis Lydia
Published: March 2005

Objective:  To compare the needs of patients and with those cited by psychiatrists in the current physician study to provide a more balanced view of the scope of unmet needs.

Methods:  A US‐based consensus panel categorized unmet needs according to their relevance to patients, providers, or health systems.

Results:  Patients need medications that are quicker acting, have less troublesome side‐effects, are more effective, and are significantly less expensive, and they need access to medications most likely to help them by not being at the mercy of restricted formularies. To improve communication with patients, physicians must not only listen more effectively but must also ask patients more direct and targeted questions, particularly regarding all symptoms the patient might be experiencing. Patients gave a high priority to making treatment decisions jointly with their physicians and being partners in their wellness plan. Peer support can also be extremely helpful to people who have bipolar disorder.

Conclusions:  By making efficacious, affordable medications available, improving communications, jointly creating wellness strategies and goals, and equally participating as active partners, patients and physicians can work together to achieve optimal wellness not just remission of symptoms.
Compliance Motivations: Perspectives of Farmers, Homebuilders, and Marine Facilities*
Authors: MAY PETER J.
Published: March 2005

This paper addresses the role of differing regulatory contexts in shaping compliance motivations. These are examined for farmers and environmental regulation in Denmark, homebuilders and building safety in the United States, and marine facilities and water quality in the United States. The findings show that the influence of different regulatory practices and the relevance of normative and social considerations differ among these regulatory contexts. This calls attention to the need for more research on the interplay of regulatory arrangements and contexts in shaping motivations for regulatory compliance.
PSYCHOSOCIAL FACTORS IN PATIENTS WITH CHRONIC KIDNEY DISEASE: Couples Coping in Response to Kidney Disease: A Developmental Perspective
Authors: Gee Christina B. , Howe George W. , Kimmel Paul L.
Published: March 2005

In this article we suggest that the treatment of patients with end‐stage renal disease (ESRD) should be informed by three developmental perspectives. In addition to the changes in the progression of the illness and its treatment demands over time, clinicians should consider psychosocial changes and challenges related to the developmental life stage of the patient (e.g., retirement) and the evolution of the patient's romantic relationship along a variety of dimensions that may affect his or her ability to cope with the disease (e.g., emotional support, conflict, sexual functioning). We briefly review the existing literature in each area and argue that integrating all three perspectives will facilitate the long‐term treatment success and patient's adjustment to the illness. Finally, we discuss the implications for the development of prevention and treatment interventions with patients and their spouses or partners and the importance of considering ethnic and cultural variations in treatment.
PSYCHOSOCIAL FACTORS IN PATIENTS WITH CHRONIC KIDNEY DISEASE: Quality of Life and Psychological Issues in Peritoneal Dialysis Patients
Authors: Lew Susie Q. , Piraino Beth
Published: March 2005

Both peritoneal dialysis (PD) and hemodialysis (HD) patients have diminished quality of life (QOL) scores compared to healthy patients. QOL tends to decline over time, with the perception of the quality of physical health deteriorating more than mental health. However, many patients continue to feel hopeless, anxious, and worry about finances, loss of sexual function, family burden, and loss of independence. Depression is the most widely acknowledged psychosocial factor seen in patients with chronic kidney disease. Major depression occurs in 25% of patients facing impending dialysis. Once on PD, the proportion with major depression sharply declines to approximately 6%. This may be due to adjustment to dialysis, but may also be because depressive symptoms are associated with an increased risk of death. A low QOL score and depression are associated with higher comorbidity, poorer nutritional status, anemia, lower residual renal function, and increased hospitalization rates. Increased depressive scores are independently predictive of an elevated peritonitis risk, perhaps due to inattentiveness, or alternatively from a decrease in immune defenses. Small molecule clearances appear to have little to do with depressive symptoms. Depression is a significant problem in PD and other dialysis patients. There is an interrelationship between psychosocial factors, perception of illness, and clinical outcome that requires further study. Serial and simple measures of both depression and QOL should be obtained routinely in all PD patients. This permits rapid recognition of problems and may enhance patients’ education on the importance of depression. Further research on interventions is urgently needed.
Microwave‐Hydrothermal Synthesis and Hyperfine Characterization of Praseodymium‐Doped Nanometric Zirconia Powders
Authors: Bondioli Federica , Leonelli Cristina , Manfredini Tiziano , Ferrari Anna Maria , Caracoche Maria Cristina , Rivas Patricia Claudia , Rodríguez Agustín Mario
Published: March 2005

This work focuses on the microwave‐assisted hydrothermal synthesis of praseodymium‐doped zirconia and on the subsequent evaluation of the effect of synthesis conditions on powder properties. Pure and 10 mol% Pr‐doped zirconia samples have been analyzed by X‐ray diffraction (XRD) and the perturbed angular correlations hyperfine technique, which probes the nearest environments of zirconium ions. At atomic scale, as determined from perturbed angular correlation data, the XRD amorphous fraction of the as‐obtained powders exhibits a tetragonal‐like structure. The pure powder becomes partially stabilized and the doped powder is a substitutional solid solution of praseodymium in tetragonal zirconia.
Effects of the Use of Pore Formers on Performance of an Anode Supported Solid Oxide Fuel Cell
Authors: Haslam Jeffery J. , Pham Ai‐Quoc , Chung Brandon W. , DiCarlo Joseph F. , Glass Robert S.
Published: March 2005

The effects of amount of pore former used to produce porosity in the anode of an anode supported planar solid oxide fuel cell were examined. The pore‐forming material utilized was rice starch. The reduction rate of the anode material was measured by Thermogravimetric analysis to qualitatively characterize the gas transport within the porous anode materials. Fuel cells with varying amounts of porosity produced by using rice starch as a pore former were tested. The performance of the fuel cell was the greatest with an optimum amount of pore former used to create porosity in the anode. This optimum is believed to be related to a trade off between increasing gas diffusion to the active three‐phase boundary region of the anode and the loss of performance because of the replacement of active three‐phase boundary regions of the anode with porosity.
The Effect of Texture and Microstructure on the Macroscopic Properties of Polycrystalline Piezoelectrics: Application to Barium Titanate and PZN–PT
Authors: García R. Edwin , Craig Carter W. , Langer Stephen A.
Published: March 2005

The effects of crystallographic texture and microstructure are analyzed for polycrystalline tetragonal BaTiO3, pseudotetragonal PZN–PT, and cubic BaTiO3. For tetragonal BaTiO3 and pseudotetragonal PZN–PT, we demonstrate that a high anisotropy of the single‐crystal properties induces an apparent enhancement in the macroscopic piezoelectric response. For tetragonal BaTiO3, the predicted macroscopic piezoelectric constants d31 and d33 are enhanced with respect to its single‐crystal value at the expense of the spatial contributions from d15. For samples possessing fiber texture, an optimal response is predicted for samples that are not perfectly textured. Similarly, an apparent enhancement of the macroscopic value of d15 is predicted for PZN–PT. For cubic BaTiO3, the low anisotropy of the underlying crystal properties induces a uniform decrease of the macroscopic electrostrictive constant, Q11, with decreasing texture. A completely random polycrystal provides 0.85±0.05 times its single‐crystal response.
Tribological Properties of WC–ZrO2Nanocomposites
Authors: Venkateswaran T. , Sarkar D. , Basu B.
Published: March 2005

In the present work, the fretting wear (mode I, linear relative tangential displacement, constant normal load) of a newly developed nanocomposite is investigated with varying load (2–10 N) and test duration (10 000–100 000 cycles). A detailed morphological investigation of worn surface is carried out using a Stylus surface profilometer, optical microscope, SEM, and electron probe microanalyser (EPMA). A clear transition in friction and wear behavior with load is observed. Based on the worn surface topography and wear debris analysis, the wear mechanisms are proposed. The extremely low wear rate (10−8mm3/N·m) along with low wear depth (<1 μm) indicates high wear resistance of nanoceramic composites. The high fretting wear resistance of the nanocomposites as well as the observed tribological properties are discussed in terms of material properties, abrasion, and tribochemical wear phenomenon.
Microstructural and Thermoelectric Characteristics of Zinc Oxide‐Based Thermoelectric Materials Fabricated Using a Spark Plasma Sintering Process
Authors: Kim Kyoung Hun , Shim Seung Hwan , Shim Kwang Bo , Niihara Koichi , Hojo Junichi
Published: March 2005

M‐doped zinc oxide (ZnO) (M=Al and/or Ni) thermoelectric materials were fully densified at a temperature lower than 1000°C using a spark plasma sintering technique and their microstructural evolution and thermoelectric characteristics were investigated. The addition of Al2O3 reduced the surface evaporation of pure ZnO and suppressed grain growth by the formation of a secondary phase. The addition of NiO promoted the formation of a solid solution with the ZnO crystal structure and caused severe grain growth. The co‐addition of Al2O3 and NiO produced a homogeneous microstructure with a good grain boundary distribution. The microstructural characteristics induced by the co‐addition of Al2O3 and NiO have a major role in increasing the electrical conductivity and decreasing the thermal conductivity, resulting from an increase in carrier concentration and the phonon scattering effect, respectively, and therefore improving the thermoelectric properties. The ZnO specimen, which was sintered at 1000°C with the co‐addition of Al2O3 and NiO, exhibited a ZT value of 0.6 × 10−3 K−1, electrical conductivity of 1.7 × 10−4Ω−1·m−1, the thermal conductivity of 5.16 W·(m·K)−1, and Seebeck coefficient of −425.4 μV/K at 900°C. The ZT value obtained respects the 30% increase compared with the previously reported value, 0.4 × 10−3 K−1, in the literature.
Apatite Converted from 3‐D Ordered Macroporous Sol–Gel Bioactive Glass (3DOM‐BG) Particles
Authors: Zhang Kai , Francis Lorraine F. , Yan Hongwei , Stein Andreas
Published: March 2005

3‐D ordered macroporous sol–gel bioactive glass particles (3DOM‐BG, pore size: 345 nm; molar composition: 75 SiO2–21 CaO–4 P2O5) were converted into nano‐crystalline calcium‐deficient carbonate apatite after soaking at 37°C in simulated body fluid. The as‐formed, flake‐like apatite transformed into a coral‐like, highly crystalline hydroxyapatite with a minor tri‐calcium phosphate phase after heating for 1 h at a temperature of 700°C. Fourier transform infrared results show the loss of carbonate and isolation of hydroxyl during heating. The heat treatment improved the apatite's resistance to dissolution in a buffer solution (pH=5).
Distinguishing Primary Headache Disorders from Cervicogenic Headache: Clinical and Therapeutic Implications
Authors: Bogduk Nikolai
Published: March 2005

The objectives of this article are to encapsulate the literature on the clinical aspects of cervicogenic headache, in order to help readers understand how cervicogenic headache can be distinguished from other primary headaches, and how it might be treated. Cervicogenic headache has evolved as a contentious and controversial entity. Tensions have developed concerning how it should be diagnosed, and if it at all exists as an entity. The literature is summarized and appraised in the form of a narrative review. Two conflicting approaches have been used to define cervicogenic headache. One has pursued the definition according to clinical features, but the validity of this approach has not been established. The other approach ignores clinical features and seeks instead to establish the diagnosis by demonstrating a cervical source of pain in the head. For that purpose diagnostic blocks have been used to pinpoint sources of pain in the upper cervical joints. Few treatments have been tested and validated for this condition. In conclusion, cervicogenic headache can be suspected but not diagnosed on the basis of clinical features. The diagnosis ultimately requires diagnostic blocks. Intra‐articular steroids may be a useful treatment. Complete relief of headache can be achieved by radiofreqeuncy neurotomy in patients whose headache stems from the C2–3 zygapophysial joint.
Long‐term effects of microgravity on the swimming behaviour of young rats
Authors: Walton Kerry D. , Benavides Louis , Singh Neeraj , Hatoum Nagi
Published: March 2005

The postnatal development of sensory systems has been shown in studies over the last four decades to be influenced by experience during critical periods of development. We report here that similar experience‐dependent development can be observed in the swimming behaviour of young rats reared from postnatal day 14 (P14) to P30 in the reduced gravitational field of low earth orbit. Animals flown in space when placed in the water on the day of landing maintained their head and forelimbs in a balanced posture. However, until the animals began to swim, their hindquarters showed little lateral postural control resulting in rotation about the longitudinal axis (60°± 4 deg). Such results suggest an ‘unlinking’ of postural control of the forequarters from the hindquarters in the early hours after landing. Similar instability seen in animals age‐matched to the day of launch (97 ± 7 deg) and in ground control animals (9 ± 3 deg) was corrected within one or two rotations, even in the absence of swimming. Animals flown in space began to swim sooner after being placed in the water, and the duration of swimming strokes was shorter than in control animals. Motion analysis revealed a difference in the swimming style on landing day. In flight animals, the knee joint was more flexed throughout the stroke, there was a narrower range of movement, and the linear velocity of the tip of the foot was faster throughout most of the stroke than in age‐matched control animals. Thus, posture in the water as well as swimming speed and style were altered in the animals flown in space. Some of these characteristics persisted for as long as the animals were followed (30 days). These included the short pre‐swimming interval and short stroke duration in flight animals. These findings clearly show that an altered gravitational field influences the postnatal development of motor function. The nature of the differences between animals reared in space for 16 days and those remaining on the ground reflects an adaptation of the flight animals to the microgravity environment. The data suggest that the most fundamental of these adaptations is a resetting of the basic motor rhythm to a higher frequency.
Leptin repletion restores depressed β‐adrenergic contractility in ob/ob mice independently of cardiac hypertrophy
Authors: Minhas Khalid M. , Khan Shakil A. , Raju Shubha V. Y. , Phan Alexander C. , Gonzalez Daniel R. , Skaf Mike W. , Lee Kwangho , Tejani Ankit D. , Saliaris Anastasies P. , Barouch Lili A. , O'Donnell Christopher P. , Emala Charles W. , Berkowitz Dan E. , Hare Joshua M.
Published: March 2005

Impaired leptin signalling in obesity is increasingly implicated in cardiovascular pathophysiology. To explore mechanisms for leptin activity in the heart, we hypothesized that physiological leptin signalling participates in maintaining cardiac β‐adrenergic regulation of excitation–contraction coupling. We studied 10‐week‐old (before development of cardiac hypertrophy) leptin‐deficient (ob/ob, n= 12) and C57Bl/6 (wild‐type (WT), n= 15) mice at baseline and after recombinant leptin infusion (0.3 mg kg−1 day−1 for 28 days, n= 6 in each group). Ob/ob‐isolated myocytes had attenuated sarcomere shortening and calcium transients ([Ca2+]i) versus WT (P < 0.01 for both) following stimulation of the β‐receptor (with isoproterenol (isoprenaline)) or at the post‐receptor level (with forskolin and dibutryl‐cAMP). In addition, sarcoplasmic reticulum (SR) Ca2+ stores were depressed. Leptin replenishment in ob/ob mice restored each of these abnormalities towards normal without affecting gross (wall thickness) or microscopic (cell size) measures of cardiac architecture. Immunoblots revealed alterations of several proteins involved in excitation–contraction coupling in the ob/ob mice, including decreased abundance of Gsα‐52 kDa, as well as alterations in the expression of Ca2+ cycling proteins (increased SR Ca2+‐ATPase, and depressed phosphorylated phospholamban). In addition, protein kinase A (PKA) activity in ob/ob mice was depressed at baseline and correctable towards the activity found in WT with leptin repletion, a finding that could account for impaired β‐adrenergic responsiveness. Taken together, these data reveal a novel link between the leptin signalling pathway and normal cardiac function and suggest a mechanism by which leptin deficiency or resistance may lead to cardiac depression.
High-Throughput Mapping of a Dynamic Signaling Network in Mammalian Cells
Authors: Barrios-Rodiles Miriam , Brown Kevin R. , Ozdamar Barish , Bose Rohit , Liu Zhong , Donovan Robert S. , Shinjo Fukiko , Liu Yongmei , Dembowy Joanna , Taylor Ian W. , Luga Valbona , Przulj Natasa , Robinson Mark , Suzuki Harukazu , Hayashizaki Yoshihide , Jurisica Igor , Wrana Jeffrey L.
Published: March 2005

Signaling pathways transmit information through protein interaction networks that are dynamically regulated by complex extracellular cues. We developed LUMIER (for luminescence-based mammalian interactome mapping), an automated high-throughput technology, to map protein-protein interaction networks systematically in mammalian cells and applied it to the transforming growth factorâÎ² (TGFÎ²) pathway. Analysis using self-organizing maps and
k
-means clustering identified links of the TGFÎ² pathway to the p21-activated kinase (PAK) network, to the polarity complex, and to Occludin, a structural component of tight junctions. We show that Occludin regulates TGFÎ² type I receptor localization for efficient TGFÎ²-dependent dissolution of tight junctions during epithelial-to-mesenchymal transitions.
Amplification of Acetylcholine-Binding Catenanes from Dynamic Combinatorial Libraries
Authors: Lam Ruby T. S. , Belenguer Ana , Roberts Sarah L. , Naumann Christoph , Jarrosson Thibaut , Otto Sijbren , Sanders Jeremy K. M.
Published: March 2005

Directed chemical synthesis can produce a vast range of molecular structures, but the intended product must be known at the outset. In contrast, evolution in nature can lead to efficient receptors and catalysts whose structures defy prediction. To access such unpredictable structures, we prepared dynamic combinatorial libraries in which reversibly binding building blocks assemble around a receptor target. We selected for an acetylcholine receptor by adding the neurotransmitter to solutions of dipeptide hydrazones [proline-phenylalanine or proline-(cyclohexyl)alanine], which reversibly combine through hydrazone linkages. At thermodynamic equilibrium, the dominant receptor structure was an elaborate [2]-catenane consisting of two interlocked macrocyclic trimers. This complex receptor with a 100 nM affinity for acetylcholine could be isolated on a preparative scale in 67% yield.
Synthesis and Crystal Structure of 17-Allyl-4,5-anhydro-7α-[(R)-1-hydroxy-1-methyl-3-(2-thienyl)propyl]-6-methoxy-6,14-ethanomorphinan-3,4,5-triol
Authors: Liu He , Wang Jingyan , Zhong Bohua
Published: March 2005

17-Allyl-4,5-anhydro-7α-[(R)-1-hydroxy-1-methyl-3-(2-thienyl)propyl]-6-methoxy-6,14-ethanomorphinan-3,4,5-triol (thienorphine 6) was synthesized and structurally characterized by NMR spectra, ESI-MS and X-ray diffraction. The crystal structure indicates that thienorphine maintained the main rigid structure of morphine while containing the C6-C14 ethano bridge. The allyl group is located in the equatorial position as expected. The packing diagram of 6 showed the presence of intramolecular and intermolecular O-H···O hydrogen bonds linking the molecules into a zigzag infinite quasi-one-dimensional chain structure.
A new likelihood for simultaneously estimating von Bertalanffy growth parameters, gear selectivity, and natural and fishing mortality
Authors: Taylor Nathan G , Walters Carl J , Martell Steven J.D.
Published: March 2005

Gear selectivity and the cumulative effects of size-selective fishing produce bias in the length-at-age samples used to estimate the von Bertalanffy growth parameters. In fished populations, fast-growing young fish and slow-growing old fish are overrepresented in sizeage samples. To account for such effects, we treated size-at-age observations as multinomial samples, with expected catches in each sizeage category dependent on growth parameters, growth variation, size selectivity, abundance at age, and the history of exploitation. Using simulated data sets, estimated growth parameters using the multinomial likelihood were unbiased when fishing mortality was not too high and the shape of the vulnerability function was correct. In contrast, estimated growth parameters using a least squares approach overestimated the metabolic growth coefficient (K) and underestimated mean asymptotic length (L∞). Models that do not explicitly account for the effects of fishing and size selectivity underestimated L∞ and overestimated K. We estimate growth parameters for northern pikeminnow (Ptychocheilus oregonensis) as an example of the method and document a stunted "pigmy" population with an L∞ of 175-mm fork length, attributing its small size to effects of high density and (or) a short growing season.
Epilithic algal abundance in relation to anthropogenic changes in phosphorus bioavailability and limitation in mountain rivers
Authors: Bowman Michelle F , Chambers Patricia A , Schindler David W
Published: March 2005

Low-level cultural eutrophication (0.13.8 µ·L1 increase in total phosphorus (TP)) of oligotrophic mountain rivers resulted in 4- to 30-fold increases in benthic algal abundance. Because anthropogenic P was more bioavailable than naturally occurring P, there were higher algal abundances downstream relative to upstream of nutrient point sources at a given P concentration. Neither TP nor soluble reactive P concentrations were indicative of P bio availability. Of the measures studied, epilithic alkaline phosphatase activity was most strongly correlated with algal abundance, most indicative of P bioavailability and thus the most precise indicator of P limitation. Although changes in dissolved inorganic nitrogen (DIN) to P ratios in river water and carbon (C) to P ratios in epilithon were consistent with changes in algal abundance and nutrient limitation, published water DIN to TP and tissue C to P ratio thresholds did not always yield accurate predictions of the type or degree of nutrient limitation. Epilithic N to P ratios and algal growth on nutrient-diffusing substrates were also inexact measures of epilithic nutrient limitation but, unlike other measures, were not strongly correlated with algal abundance. Thus, the predictability of the benthic algal response to anthropogenic nutrient additions in oligotrophic rivers will be improved by using measures indicative of both nutrient limitation and bioavailability.
Seismic uplift capacity of inclined strip anchors
Authors: Choudhury Deepankar , Subba Rao K S
Published: March 2005

Uplift capacities of inclined strip anchors in soil with a horizontal ground surface are obtained under seismic conditions. Limit equilibrium approaches with a logarithm-spiral failure surface and pseudostatic seismic forces are adopted in the analysis. The results are presented in the form of seismic uplift capacity factors as functions of anchor inclination, embedment ratio, angle of internal friction of the soil, and horizontal and vertical seismic acceleration coefficients. The uplift capacity factors are worked out separately for cohesion, surcharge, and density components. Use of the principle of superposition for calculating anchor uplift capacity is validated. The vertical seismic acceleration coefficient always reduces the uplift capacity, whereas the horizontal seismic acceleration coefficient reduces the uplift capacity in most cases. The roles of anchor embedment ratio, soil friction angle, and anchor inclination in determination of the seismic uplift capacity are also discussed. Comparisons of the proposed method with available theories in the seismic case are also presented. The present study gives the minimum seismic uplift capacity factors compared with the existing theory.Key words: seismic uplift capacity factors, inclined strip anchors, limit equilibrium, pseudostatic, cϕ soil.
Controlling suction by the vapour equilibrium technique at different temperatures and its application in determining the water retention properties of MX80 clay
Authors: Tang Anh-Minh , Cui Yu-Jun
Published: March 2005

Problems related to unsaturated soils are frequently encountered in geotechnical or environmental engineering works. In most cases, for simplicity, one can study the problems by considering the suction effects on volume change or shear strength under isothermal conditions. Often, under these conditions, a temperature-independent water retention curve is considered in the analysis  obviously a simplification. When the temperature changes are too significant to be ignored, it is necessary to account for the thermal effects. This note presents a method for controlling suction with the vapour equilibrium technique at different temperatures. First, calibration of various saturated saline solutions was carried out at temperatures ranging from 20 °C to 60 °C. A mirror psychrometer was used to measure relative humidity generated by saturated saline solutions at different temperatures. The results obtained were in good agreement with the data from the literature. This information was then used to determine the water retention properties of MX80 clay, which showed that the retention curve shifts downward with increasing temperature.Key words: vapour equilibrium technique, hygrometer, water retention curve, temperature effects, compacted bentonite.
Forest harvesting, resource-based tourism, and remoteness: an analysis of northern Ontario's sport fishing tourism
Authors: Hunt Len M , Boxall Peter , Englin Jeffrey , Haider Wolfgang
Published: March 2005

This paper assesses the impact that the routine application of Ontario's forest management planning process has on the revenue generation of sport fishing tourism sites. The analysis employs a hedonic pricing model to examine jointly these effects on revenue for three tourism experiences. These tourism experiences offer different degrees of remoteness, and as a consequence, require different levels of effort and cost to visit. Modelling the relationship between price and attributes of sites such as remoteness permits the analysis to forecast the revenue generation potential of sport fishing tourism sites under a range of forest management schemes. The results show that the extent of forest harvesting had no statistical relationship with prices charged for fishing packages at road-, boat-, or train-accessible sites and a negative but small impact on the prices charged for fishing packages at sites accessible by float plane.
ON THE EXISTENCE OF A STABLE PERIODIC SOLUTION OF TWO IMPACTING OSCILLATORS WITH DAMPING
Authors: CZOLCZYNSKI KRZYSZTOF , KAPITANIAK TOMASZ
Published: March 2005

A system that consists of two impacting oscillators with damping has been considered in this paper. In the first part, a method of analytical determination of the existence of periodic solutions to the equations of motion and a method of analysis of the stability of these solutions are presented. The results of the computations carried out by these methods have been illustrated with a few examples. In the second part of the paper, the results of some numerical investigations are presented. The goal of these studies is to determine, in which regions of parameters characterizing the system, the periodic motion with one impact per period exists and is stable.
STEPS TOWARDS CRYPTANALYSIS OF CHAOTIC ACTIVE/PASSIVE DECOMPOSITION ENCRYPTION SCHEMES USING AVERAGE DYNAMICS ESTIMATION
Authors: TENNY ROY , TSIMRING LEV S.
Published: March 2005

We analyze the security of encryption schemes based on chaos synchronization and active/passive decomposition. The security is quantified by the number of transmitted samples that has to be acquired in order to reconstruct the transmitted message with an accuracy that may compromise the transmitted information. The dynamics is estimated as the average of dynamics of the observed data within a small neighborhood of the time delay embedding phase space. We examine the factors that affect the choice of embedding dimension and neighborhood size by the unauthorized receiver. We show that the security can be enhanced by mixing a large randomly modulated message component with a smaller chaotic component while keeping the message modulation fine grained. This result is in contrast to the common approach to ensure security by adding a small message component to a larger chaotic component. Further, we show that even when a low dimensional chaotic map is used, then the unauthorized receiver is required to use a reconstruction embedding dimension that can be made large by using chaotic dynamics with large conditional negative Lyapunov exponent. This result allows one to avoid the common restriction to use only high dimensional chaotic dynamics to maintain security. We also suggest guidelines for the design of efficient active passive/passive decomposition schemes in order to maintain low transmission power, fast synchronization, and yet preserve security. We demonstrate our analysis using a relatively simple encryption scheme based on a one-dimensional chaotic tent map.
A REMARK ON HETEROCLINIC BIFURCATIONS NEAR STEADY STATE/PITCHFORK BIFURCATIONS
Authors: KIRK VIVIEN , KNOBLOCH EDGAR
Published: March 2005

We consider a bifurcation that occurs in some two-dimensional vector fields, namely a codimension-one bifurcation in which there is simultaneously the creation of a pair of equilibria via a steady state bifurcation and the destruction of a large amplitude periodic orbit. We show that this phenomenon may occur in an unfolding of the saddle-node/pitchfork normal form equations, although not near the saddle-node/pitchfork instability. By construction and analysis of a return map, we show that the codimension-one bifurcation emerges from a codimension-two point at which there is a heteroclinic bifurcation between two saddle equilibria, one hyperbolic and the other nonhyperbolic. We find the same phenomenon occurs in the normal form equations for the hysteresis/pitchfork bifurcation, in this case arbitrarily close to the instability, and show there are restrictions regarding the way in which such dynamics can occur near pitchfork/pitchfork bifurcations. These conclusions carry over to analogous phenomena in normal forms for steady state/Hopf bifurcations.
A NONLINEAR DYNAMICS PERSPECTIVE OF WOLFRAM'S NEW KIND OF SCIENCE PART III: PREDICTING THE UNPREDICTABLE
Authors: CHUA LEON O. , SBITNEV VALERY I. , YOON SOOK
Published: March 2005

We prove rigorously the four cellular automata local rules 110, 124, 137 and 193 have identical dynamic behaviors capable of universal computations. We exploit Felix Klein's remarkable Vierergruppe to partition the 256 local rules studied empirically by Wolfram into 89 global equivalence classes of which only 50 may exhibit complex dynamics. We define a 24-element rotation group which induces 30 local equivalence classes of nonlinear difference equations whose parameters can be mapped into each other among members of the same class.
Hindlimb unloading alters nitric oxide and autonomic control of resting arterial pressure in conscious rats
Authors: Mueller Patrick J. , Foley C. Michael , Hasser Eileen M.
Published: March 2005

After periods of microgravity or bed rest, individuals often exhibit reduced V̇o2 max, hypovolemia, cardiac and vascular effects, and autonomic dysfunction. Recently, alterations in expression of vascular and central nervous system NO synthase (NOS) have been observed in hindlimb-unloaded (HU) rats, a model used to simulate physiological effects of microgravity or bed rest. We examined the effects of 14 days of hindlimb unloading on hemodynamic responses to systemic NOS inhibition in conscious control and HU rats. Because differences in NO and autonomic regulation might occur after hindlimb unloading, we also evaluated potential differences in resting autonomic tone and effects of NOS inhibition after autonomic blockade. Administration of nitro-l-arginine methyl ester (l-NAME; 20 mg/kg iv) increased mean arterial pressure (MAP) to similar levels in control and HU rats. However, the change in MAP in response to l-NAME was less in HU rats, that had an elevated baseline MAP. In separate experiments, atropine (1 mg/kg iv) increased heart rate (HR) in control but not HU rats. Subsequent administration of the ganglionic blocker hexamethonium (30 mg/kg iv) decreased MAP and HR to a greater extent in HU rats. Administration of l-NAME after autonomic blockade increased MAP in both groups to a greater extent compared with intact conditions. However, the pressor response to l-NAME was still reduced in HU rats. These data suggest that hindlimb unloading in rats reduces peripheral NO as well as cardiac parasympathetic tone. Along with elevations in sympathetic tone, these effects likely contribute to alterations in vascular control and changes in autonomic reflex function following spaceflight or bed rest.
Arterial pulse modulated activity is expressed in respiratory neural output
Authors: Dick Thomas E. , Shannon Roger , Lindsey Bruce G. , Nuding Sarah C. , Segers Lauren S. , Baekey David M. , Morris Kendall F.
Published: March 2005

Although it is well-established that sympathetic activity is modulated with respiration, it is unknown whether neural control of respiration is reciprocally influenced by cardiovascular function. Even though previous studies have suggested the existence of pulse modulation in respiratory neurons, they could not exclude the possibility that such cells were involved in cardiovascular rather than respiratory motor control, owing to neuroanatomic and functional overlaps between brain stem neurons involved in respiratory and cardiovascular control. The aim of this study was to test the hypothesis that respiratory motoneurons and putative premotoneurons are modulated by arterial pulse. An existing data set composed of 72 well-characterized, respiratory-modulated brain stem motoneurons and putative premotoneurons was analyzed using δ2, a recently described statistic that quantifies the magnitude of arterial pulse-modulated spike activity [Dick TE and Morris KF. J Physiol 556: 959–970, 2004]. Neuronal activity was recorded in the rostral and caudal ventral respiratory groups of 19 decerebrate, neuromuscular-blocked, ventilated cats. Axonal projections were identified by rectified and unrectified spike-triggered averages of recurrent laryngeal nerve activity or by antidromic activation from spinal stimulation electrodes. The firing rates of ∼30% of these neurons were modulated in phase with both the respiratory and cardiac cycles. Furthermore, arterial pulse modulation occurred preferentially in the expiratory phase in that only expiratory neurons had high δ2 values and only expiratory activity had significant δ2 values after partitioning tonic activity into the inspiratory and expiratory phases. The results demonstrate that both respiratory motoneurons and putative premotoneuronal activity can be pulse modulated. We conclude that a cardiac cycle-related modulation is expressed in respiratory motor activity, complementing the long-recognized respiratory modulation of sympathetic nerve activity.
Intracellular pH during sequential, fatiguing contractile periods in isolated singleXenopusskeletal muscle fibers
Authors: Stary C. M. , Hogan M. C.
Published: March 2005

The purpose of the present study was to test the hypothesis that a preceding contractile period in isolated single skeletal muscle fibers would attenuate the decrease in pH during an identical, subsequent contractile period, thereby reducing the rate of fatigue. Intact single skeletal muscle fibers ( n = 9) were isolated from Xenopus lumbrical muscle and incubated with the fluorescent cytosolic H+indicator 2′,7′-bis-(2-carboxyethyl)-5( 6 )-carboxyfluorescein (BCECF) AM for 30 min. Two identical contractile periods were performed in each fiber, separated by a 1-h recovery period. Force and intracellular pH (pHi) fluorescence were measured simultaneously while fibers were stimulated (tetanic contractions of 350-ms trains with 70-Hz stimuli at 9 V) at progressively increasing frequencies (0.25, 0.33, 0.5, and 1 contraction/s) until the development of fatigue (to 60% initial force). No significant difference ( P < 0.05) was observed between the first and second contractile periods in initial force development, resting pHi, or time to fatigue (5.3 ± 0.5 vs. 5.1 ± 0.6 min). However, the relative decrease in the BCECF fluorescence ratio (and therefore pHi) from rest to the fatigue time point was significantly greater ( P < 0.05) during the first contractile period (to 65 ± 4% of initial resting values) compared with the second (77 ± 4%). The results of the present study demonstrated that, when preceded by an initial fatiguing contractile period, the rise in cytosolic H+concentration in contracting single skeletal muscle fibers during a second contractile period was significantly reduced but did not attenuate the fatigue process in the second contractile period. These results suggest that intracellular factors other than H+accumulation contribute to the fall in force development under these conditions.