bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy balance and temperature relations of Azorella compacta, a high‐elevation cushion plant of the central Andes
Authors: Kleier C. , Rundel P. 
Published: September 2008

AbstractThe environmental relationships and ecophysiology of Azorella compacta, a giant cushion plant, were investigated in Parque Nacional Lauca, Chile (18°10′–18°25′ S and 69°16′ W, 4400 m asl). The diurnal temperature range can reach 42 °C on some days of the year. The surface temperature of A. compacta was 13 °C below that of the air temperature of −7 °C at dawn, but from midmorning to late afternoon, the plant surface temperature remained within a few degrees of the air temperature. Soil surface temperatures did not differ between north‐ and south‐facing slopes, but a model showed an increase in radiation reception by north‐facing slopes throughout most of the year. Gas exchange measurements of A. compacta measured at the onset of the wet season ranged from −0.6662 to 11.4 μmol·m−2·s−1, and maximum stomatal conductance (Gs) was 410 mmol·m−2·s−1. The estimated light compensation point was 89 μmol·m−2·s−1 and estimated light saturation occurred at about 1280 μmol·m−2·s−1. Diurnal water potential measurements for A. compacta ranged from −1.67 to −2.65 MPa. This is one of the first ecophysiological studies of a tropical alpine cushion plant.
Differential and interactive effects of temperature and photoperiod on budburst and carbon reserves in two co‐occurring Mediterranean oaks
Authors: Sanz‐Pérez V. , Castro‐Díez P. , Valladares F. 
Published: September 2008

AbstractEffects of temperature and photoperiod and their interactions on budburst and on the use of carbon reserves were examined in two Mediterranean oaks differing in wood anatomy and leaf habit. Seedlings of Quercus ilex subsp. ballota (evergreen and diffuse‐porous wood) and Q. faginea (semi‐deciduous and ring‐porous wood) were grown under two temperatures (12 and 19 °C) and two photoperiods (10 and 16 h) in a factorial experiment. In the 16 h photoperiod at 19 °C, photosynthesis was suppressed in half of the seedlings by covering leaves with aluminium foil. The concentration of soluble sugars, starch and lipids in leaves, stems and roots was assessed before and after budburst. Under the 12 °C treatment (mean current temperature in early spring in the Iberian Peninsula), budburst in Q. faginea occurred earlier than in Q. ilex. Higher temperature promoted earlier budburst in both species, mostly under the 16 h photoperiod. This response was less pronounced in Q. faginea because its budburst was also controlled by photoperiod, and because this species needs to construct a new ring of xylem before budburst to supply its growth demands. Therefore, dates of budburst of the two species became closer to each other in the warmer treatment, which might alter competitive relations between the species with changing climate. While Q. ilex relied on carbon reserves for budburst, Q. faginea relied on both carbon reserves and current photoassimilates. The different responses of the two Quercus species to temperature and photoperiod related more to xylem structure than to the source of carbon used for budburst.
Immunohistochemical Analysis of Low‐Temperature Methylmethacrylate Resin‐Embedded Goat Tissues
Authors: Vertenten G. , Vlaminck L. , Ducatelle R. , Lippens E. , Cornelissen M. , Gasthuys F. 
Published: September 2008

SummaryGoats are frequently used as a suitable animal model for tissue engineering. Immunohistochemistry can be helpful in improving the understanding and evaluation of the in vivo tissue responses at a molecular level. Several commercially available antibodies (KI67, vimentin, CD31, core‐binding factor alpha‐1, osteocalcin, alkaline phosphatase, MAC387, CD3, CD20, CD20cy, CD79 and CD45) were evaluated on Technovit 9100 New© embedded goat tissues. Only vimentin, osteocalcin, MAC387 and CD3 revealed positive staining. These antibodies can be routinely used to evaluate goat tissues at molecular level. The use and development of alternative antibodies might further supplement and complete the possibilities for immunohistochemical analysis of goat tissue samples.
Electron Microscopic Study of the Porcine Choroid Plexus Epithelium
Authors: De Spiegelaere W. , Casteleyn C. , Van Den Broeck W. , Simoens P. 
Published: September 2008

SummaryThe choroid plexus (CP) is a highly vascularized organ in the brain ventricles which acts as the main producer of cerebrospinal fluid (CSF). A study of the surface ultrastructure of the porcine CP was performed using scanning and transmission electron microscopy. The vascular walls of the capillaries were fenestrated. Epiplexus cells of different morphology were abundant on top of the epithelial surface. Two types of epithelial cells were present, characterized by the presence or absence of microvilli. Some epithelial cells contained cilia while other cells had large secretory protrusions called blebs. In the choroid epithelium of the lateral ventricles, some cells with large depressions were present. Cells with peduncles, such as recently discovered in the buffalo, could not be recognized. The variability of the choroidal surface structures clearly indicates the active role of the CP in the formation and maintenance of the CSF and its components.
A Morphological Study of Skeletal Development in Turkey during the Pre‐Hatching Stage
Authors: Atalgin S. H. , Kürtül I. 
Published: September 2008

SummarySkeletal chondrofication, ossification and growth of turkey embryos were investigated and analysed to enable assessment of the developmental status and evaluation of the experimental effects on skeletal development, skeletal mutations and development of cultured embryos. Ten embryos were prepared every 24 h from 8 to 28 days of incubation. The fixed embryos were cleared and stainedin totowith Alcian blue & Alizarin red for cartilage and ossified components, respectively. Observation of the skeleton was performed under a stereoscopic microscopy, with special attention to the timing of chondrofication and ossification of the bones. The first occurrence of the primary ossification centres was observed in the femur, tibiotarsus, and the dentary and supra‐angular of the mandible on the 12th day, followed immediately by the other long bones. Skeletal features of the skull were determined to show the latest appearance of cartilage and ossification. Hence, all elements of the hyolingual apparatus remained cartilaginous until hatching took place except for the ceratobranchial. Even though the vertebral column chondrified earlier as compared with the ribs and sternum, they ossified later. While chondrofication was present in all the regions of the vertebral column at the same time, ossification progressed from the cervical through caudal regions. The growth rate of the femur was eminently higher than that of the humerus with increase in time, particularly after the 20th day of incubation. This seems to be obviously natural because the eggs used in the study are from the broiler turkey, which gains giant muscle mass at a very short period; precocity is probably at the expense of the bones of the leg rather than those of the wing.
ULTRASOUND‐MEDIATED MICROBUBBLE DESTRUCTION ENHANCES THE EFFICACY OF BONE MARROW MESENCHYMAL STEM CELL TRANSPLANTATION AND CARDIAC FUNCTION
Authors: Song Xiang , Zhu Hong , Jin Lijuan , Wang Junfeng , Yang Qinghui , Jin Peng , Li Xueqi 
Published: September 2008

SUMMARY

Application of ultrasound (US) to intravascular microbubble (MB) contrast agents causes small capillary ruptures. The purpose of the present study was to examine the effects of US‐mediated MB destruction on bone marrow mesenchymal stem cell (BMSC) transplantation into the infarcted myocardium and to evaluate whether this approach could improve cardiac function.
Ultrasound was applied to the anterior chest of rabbits after intravenous injection of MB followed by infusion of BMSC. There were four groups investigated: (i) a control group, in which neither US nor MB were used prior to infusion of BMSC; (ii) one group subjected to US alone prior to infusion of BMSC; (iii) another group injected with MB prior to infusion of BMSC; and (iv) a group in which US was applied to MB prior to the infusion of BMSC. Cardiac function was evaluated by echocardiography 24 h and 4 weeks after cell transplantation. All rabbits were killed to enable histological and immunochemical examination.
Echocardiography 24 h after infusion of BMSC indicated no difference in cardiac function between any of the groups, as assessed by left ventricular ejection fraction (LVEF), left ventricular end‐diastolic dimensions (LVDD), left ventricular systolic diameter (LVSD) and fractional shortening (FS%; all P > 0.05). However, 4 weeks after BMSC transplantation, there was a significant improvement in LVEF in the group subjected to US plus MB compared with the control, US alone and MB alone groups (59.5 ± 3.5, 52.5 ± 5.5, 52.8 ± 5.2 and 51.1 ± 3.5%, respectively; all P < 0.05). In addition, treatment with US plus MB significantly reduced LVDD and LVSD and increased capillary density in the infarcted area.
In conslusion, the results of the present study indicate that using US‐mediated MB destruction prior to BMSC transplantation into the infarcted myocardium improves the effectiveness of cardiac cell therapy and cardiac function in rabbits.
Reference gene selection for real‐time polymerase chain reaction in human lung cells subjected to cyclic mechanical strain
Authors: PINHU Liao , PARK John E.S. , YAO Weixue , GRIFFITHS Mark J.D. 
Published: September 2008

Background and objective:  The respiratory system is constantly exposed to mechanical forces that influence cellular phenotype in health and disease. Quantitative real‐time PCR (qPCR) is widely used to determine gene expression. The validity of qPCR depends on using stable reference genes for normalization. The effect of cyclic mechanical strain on reference gene expression by lung epithelial, fibroblast and endothelial cells has not been studied systematically.Methods:  The stability of expression of fourteen potential reference genes in response to six different regimens of cyclic mechanical strain was ranked using the geNorm tool in human lung epithelial cell lines (A549 and H441), human fetal lung fibroblasts (HFL‐1), human lung microvascular endothelial cells, primary human lung fibroblasts and primary human alveolar type 2 (hAT2) cells. The expression variation of these reference genes was also screened in unstimulated whole human lung.Results:  The stability of the selected reference genes varied within and between cell types, the variation in expression being greatest in primary cultures of hAT2. Correspondingly, the effect of expressing message for the stretch responsive gene IL‐8 normalized to the 14 reference genes was greatest in the hAT2 cells, there being an almost fivefold difference in mRNA relative change comparing different reference genes in the same samples. The minimum number of genes required to derive a reliable normalization factor for experiments on single lung cell types undergoing mechanical strain was two and for whole human lung it was four.Conclusions:  These results demonstrate that the optimal reference genes for lung cells subjected to CMS are cell type specific.
Orexin B/hypocretin 2 increases glutamatergic transmission to ventral tegmental area neurons
Authors: Borgland S. L. , Storm E. , Bonci A. 
Published: September 2008

AbstractThe orexins (hypocretins) play a crucial role in arousal, feeding and reward. Highly relevant to these functions, orexin‐containing neurons from the lateral hypothalamus project densely to the ventral tegmental area (VTA), which is the origin of dopamine projections implicated in motivation and reward. Orexin A/hypocretin 1 (oxA/hcrt‐1) can enable long‐term changes associated with drugs of abuse; however, the effects of orexin B/hypocretin 2 (oxB/hcrt‐2) on excitatory synaptic transmission in the VTA are unknown. We used whole‐cell patch‐clamp electrophysiology in rat horizontal midbrain slices to examine the effects of oxB/hcrt‐2 on excitatory synaptic transmission. We observed that oxB/hcrt‐2 has distinct effects from oxA/hcrt‐1 in the VTA. oxB/Hcrt‐2 (100 nm) increased presynaptic glutamate release in addition to a postsynaptic potentiation of NMDA receptors (NMDARs). The oxB/hcrt‐2‐mediated postsynaptic potentiation of NMDARs was mediated via activation of orexin/hypocretin 2 (OX2/Hcrt‐2) receptors and protein kinase C (PKC). Furthermore, the increase in transmitter release probability was also PKC‐dependent, but not through activation of orexin/hypocretin 1 (OX1/Hcrt‐1) or OX2/Hcrt‐2 receptors. Finally, oxB/hcrt‐2 or the selective OX2/Hcrt‐2 receptor agonist ala11‐d‐leu15‐orexin B, significantly reduced spike‐timing‐induced long‐term potentiation. Taken together, these results support a dual role for oxB/hcrt‐2 in mediating enhanced glutamatergic transmission in the VTA, and suggest that oxA/hcrt‐1 and oxB/hcrt‐2 exert different functional roles in modulating the enhancement of the motivational components of arousal and feeding.
Reward‐guided learning beyond dopamine in the nucleus accumbens: the integrative functions of cortico‐basal ganglia networks
Authors: Yin Henry H. , Ostlund Sean B. , Balleine Bernard W. 
Published: September 2008

AbstractHere we challenge the view that reward‐guided learning is solely controlled by the mesoaccumbens pathway arising from dopaminergic neurons in the ventral tegmental area and projecting to the nucleus accumbens. This widely accepted view assumes that reward is a monolithic concept, but recent work has suggested otherwise. It now appears that, in reward‐guided learning, the functions of ventral and dorsal striata, and the cortico‐basal ganglia circuitry associated with them, can be dissociated. Whereas the nucleus accumbens is necessary for the acquisition and expression of certain appetitive Pavlovian responses and contributes to the motivational control of instrumental performance, the dorsal striatum is necessary for the acquisition and expression of instrumental actions. Such findings suggest the existence of multiple independent yet interacting functional systems that are implemented in iterating and hierarchically organized cortico‐basal ganglia networks engaged in appetitive behaviors ranging from Pavlovian approach responses to goal‐directed instrumental actions controlled by action‐outcome contingencies.
Complex seasonal patterns of primary producers at the land–sea interface
Authors: Cloern James E. , Jassby Alan D. 
Published: September 2008

AbstractSeasonal fluctuations of plant biomass and photosynthesis are key features of the Earth system because they drive variability of atmospheric CO2, water and nutrient cycling, and food supply to consumers. There is no inventory of phytoplankton seasonal cycles in nearshore coastal ecosystems where forcings from ocean, land and atmosphere intersect. We compiled time series of phytoplankton biomass (chlorophyll a) from 114 estuaries, lagoons, inland seas, bays and shallow coastal waters around the world, and searched for seasonal patterns as common timing and amplitude of monthly variability. The data revealed a broad continuum of seasonal patterns, with large variability across and within ecosystems. This contrasts with annual cycles of terrestrial and oceanic primary producers for which seasonal fluctuations are recurrent and synchronous over large geographic regions. This finding bears on two fundamental ecological questions: (1) how do estuarine and coastal consumers adapt to an irregular and unpredictable food supply, and (2) how can we extract signals of climate change from phytoplankton observations in coastal ecosystems where local‐scale processes can mask responses to changing climate?
Movement of adult pecan weevils Curculio caryae within pecan orchards
Authors: Cottrell Ted E. , Wood Bruce W. 
Published: September 2008

Abstract1 The pecan weevil Curculio caryae (Horn) (Coleoptera: Curculionidae) is an indigenous pest of pecan Carya illinoinensis (Wangenh.) K. Koch, in North America. Understanding the movement of this pest from the orchard floor to host trees could lead to pest management practices that exploit weevil behaviour and thus reduce insecticide application to the entire orchard canopy. Furthermore, no information exists on diel periodicity of pecan weevil movement.2 Movement of adult pecan weevils crawling and flying to the host trunk, flying to the host canopy, crawling within the host canopy and flying between host trees was studied using four types of passive traps over four seasons. Each type of trap was used to capture weevils at different locations on or near the tree and to discriminate flying versus crawling behaviour.3 More pecan weevils crawl to the trunk than fly and a proportion of the population flies directly from the orchard floor into the pecan canopy. The majority of this movement occurs at dusk.4 The vertical distribution of weevils was generally uniform throughout the canopy but more weevils were captured in suspended traps nearest tree tops, rather than traps near the ground, when flying between trees and this was significantly so for two of 4 years.5 The results of the present study are contrary to previous reports suggesting that most adult pecan weevils fly to the pecan trunk after emergence from the soil; however, our results did indicate that a proportion of the population flies directly from the orchard floor into the pecan canopy and thus would circumvent strategies that attempt to control weevils moving up the trunk.
New type of egg attachment structure in Ephemeroptera and comparative analysis of chorion structure morphology in three species of Ephemerellidae
Authors: Ubero‐Pascal N. , Puig M. A. 
Published: September 2008

AbstractEphemeroptera eggs vary greatly in their morphology, a characteristic that has been used to solve systematic problems. The eggs of Ephemerellidae may be considered among the most studied in mayfly families, especially with regard to the number of species for which they have been described (approximately 32 species corresponding to 12 genera). However, this study provides new details of the egg morphology of three species of this family, Serratella ignita (Poda 1761), S. spinosa (Ikonomov 1961) and Torleya major (Klapalek 1905). The main finding was that the morphology and organization of the lateral attachment structures do not resemble the type normally associated with‘knob terminated coiled thread’ (KCT). The particular characteristics of this structure, never before described for Ephemeroptera, led us to propose a new type of attachment structure, the ‘multithread‐folded with terminal fibre cluster’ (MFT). We also provide a detailed description of the chorion morphology of the eggs of the three species, identifying a tear‐shaped variation in the oval sperm guide and confirming the type III polar caps in the two species of Serratella Walsh, 1862.
Purchasing Power Parity under Regime Shifts: An Application to Asian Countries*
Authors: Nusair Salah A. 
Published: September 2008

This paper re‐examines the long‐run purchasing power parity (PPP) relationship for nine Asian countries relative to the USA and Japan during a period containing significant structural breaks. The relevance of considering structural breaks in PPP tests is demonstrated by utilizing the Johansen et al. (2000) procedure that allows for up to two pre‐determined structural breaks. Using conventional tests without considering breaks, one is able to reject the null of no cointegration for only four countries. The Johansen et al. procedure clearly demonstrates the importance of allowing for structural breaks and provides strong support for long‐run PPP for all the countries, regardless of the base country, except in the case of the Philippines vis‐à‐vis Japan. The Hansen–Johansen parameter constancy test indicates stability for all the countries except the Philippines relative to the USA and Malaysia relative to Japan.
Irradiance Gradients in the Presence of Participating Media and Occlusions
Authors: Jarosz Wojciech , Zwicker Matthias , Jensen Henrik Wann 
Published: September 2008

AbstractIn this paper we present a technique for computing translational gradients of indirect surface reflectance in scenes containing participating media and significant occlusions. These gradients describe how the incident radiance field changes with respect to translation on surfaces. Previous techniques for computing gradients ignore the effects of volume scattering and attenuation and assume that radiance is constant along rays connecting surfaces. We present a novel gradient formulation that correctly captures the influence of participating media. Our formulation accurately accounts for changes of occlusion, including the effect of surfaces occluding scattering media. We show how the proposed gradients can be used within an irradiance caching framework to more accurately handle scenes with participating media, providing significant improvements in interpolation quality.
Frame Sequential Interpolation for Discrete Level‐of‐Detail Rendering
Authors: Scherzer Daniel , Wimmer Michael 
Published: September 2008

AbstractIn this paper we present a method for automatic interpolation between adjacent discrete levels of detail to achieve smooth LOD changes in image space. We achieve this by breaking the problem into two passes: We render the two LOD levels individually and combine them in a separate pass afterwards. The interpolation is formulated in a way that only one level has to be updated per frame and the other can be reused from the previous frame, thereby causing roughly the same render cost as with simple non interpolated discrete LOD rendering, only incurring the slight overhead of the final combination pass. Additionally we describe customized interpolation schemes using visibility textures.The method was designed with the ease of integration into existing engines in mind. It requires neither sorting nor blending of objects, nor does it introduce any constrains in the LOD used. The LODs can be coplanar, alpha masked, animated, impostors, and intersecting, while still interpolating smoothly.
Sample Based Visibility for Soft Shadows using Alias‐free Shadow Maps
Authors: Sintorn Erik , Eisemann Elmar , Assarsson Ulf 
Published: September 2008

AbstractThis paper introduces an accurate real‐time soft shadow algorithm that uses sample based visibility. Initially, we present a GPU‐based alias‐free hard shadow map algorithm that typically requires only a single render pass from the light, in contrast to using depth peeling and one pass per layer. For closed objects, we also suppress the need for a bias. The method is extended to soft shadow sampling for an arbitrarily shaped area‐/volumetric light source using 128‐1024 light samples per screen pixel. The alias‐free shadow map guarantees that the visibility is accurately sampled per screen‐space pixel, even for arbitrarily shaped (e.g. non‐planar) surfaces or solid objects. Another contribution is a smooth coherent shading model to avoid common light leakage near shadow borders due to normal interpolation.