bluuebunny/crossref_metadata_2025_split huggingface dataset:
PLANT TRAITS AND ECOSYSTEM GRAZING EFFECTS: COMPARISON OF U.S. SAGEBRUSH STEPPE AND PATAGONIAN STEPPE
Authors: Adler Peter B. , Milchunas Daniel G. , Sala Osvaldo E. , Burke Ingrid C. , Lauenroth William K. 
Published: June 2007

Plant functional traits provide one tool for predicting the effects of grazing on different ecosystems. To test this approach, we compared plant traits and grazing response across analogous climatic gradients in sagebrush steppe, USA (SGBR), known to have a short evolutionary history of grazing, and Patagonian steppe, Argentina (PAT), where generalist herbivores exerted stronger selective pressures. We measured grazing response by sampling vegetation and soils across distance‐from‐water gradients at arid, semiarid, and subhumid study areas in both regions. Based on a previous analysis of graminoid traits, we predicted that: (1) high forage quality in all three SGBR communities would lead to high utilization and large grazing effects, whereas low quality in arid PAT would constrain utilization and grazing impacts, with semiarid and subhumid PAT intermediate in quality and grazing response; and (2) grazing in arid PAT would cause shifts in relative abundance within the graminoid functional group, due to the large range of forage quality among graminoids, but in SGBR, where all graminoids are relatively palatable, shifts in abundance would occur between grasses and shrubs.Utilization in locations close to water was higher in SGBR than in PAT study areas. This utilization difference led to differences in grazing effects consistent with our first prediction. Abundance of graminoids increased with distance from water in all three SGBR communities and in subhumid PAT, but not in arid PAT. Shrub and total production decreased with distance in SGBR but not PAT study areas. Grazing variables explained less variation in species composition in arid PAT (43%) than in any other study area (59–74%). Grazing did not significantly influence species richness. Evidence for our second prediction was mixed. Grazing did alter the relative abundance of SGBR graminoids and shrubs, but abundance shifts among the graminoids in SGBR communities were larger than in PAT communities, counter to our prediction.This case study demonstrates how plant traits can explain relative effects of grazing on ecosystem structure and functioning, although predicting species‐specific responses remains a challenge. Regardless of their evolutionary origin, poor‐quality graminoids make the arid Patagonian steppe more resistant to overgrazing than communities dominated by more nutritious species.
DISTURBANCE HISTORY AND HISTORICAL STAND DYNAMICS OF A SEASONAL TROPICAL FOREST IN WESTERN THAILAND
Authors: Baker Patrick J. , Bunyavejchewin Sarayudh , Oliver Chadwick D. , Ashton Peter S. 
Published: June 2007

Disturbances influence forest dynamics across a range of spatial and temporal scales. In tropical forests most studies have focused on disturbances occurring at small spatial and temporal scales (i.e., gap dynamics). This is primarily due to the difficulty of reconstructing long‐term disturbance histories of forests in which most tree species lack annual growth rings. Consequently, the role of past disturbances in tropical forests is poorly understood. We used a combination of direct and indirect methods to reconstruct the historical disturbance regime and stand development patterns in mature and regenerating seasonal dry evergreen forest (SDEF) in the Huai Kha Khaeng Wildlife Sanctuary in western Thailand. Direct estimates of long‐term establishment and growth patterns were obtained from 12 tree species that form annual growth rings as a consequence of the region's strong intra‐annual rainfall seasonality. Indirect estimates of establishment patterns were obtained from analyses of stand structure and individual tree architecture and application of age‐estimation models to 10 dominant canopy‐tree species using demographic data from a large‐scale, permanent forest‐dynamics plot.The combination of direct and indirect methodologies revealed a complex disturbance history in the seasonal evergreen forest over the past 250 years. In the mid‐1800s, 200–300 ha of forest were destroyed by a catastrophic disturbance, which led to the synchronous establishment of many of the trees that presently dominate the forest canopy. Since then widespread disturbances of variable intensity have occurred at least three times (1910s, 1940s, and 1960s). These disturbances created discrete temporal pulses of establishment in small to large gaps in the forest matrix across several square kilometers. Background mortality and gap formation were evident in every decade since 1790, but these varied in intensity and frequency.The SDEF retains a distinct structural and floristic legacy from the catastrophic disturbance of the mid‐1800s. The single‐age cohort that established after the disturbance has developed a complex three‐dimensional structure as a consequence of differences in interspecific growth patterns of the canopy‐tree species and subsequent disturbances of moderate and low intensity. While no single methodological approach provided a complete picture of the disturbance history and stand development patterns of the seasonal evergreen forest, taken together they offered new insights into the long‐term dynamics of a primary tropical forest. In particular, the study highlighted the role of disturbance at multiple spatial and temporal scales and varying intensities in determining the structure and composition of a complex, species‐rich tropical forest and raises important questions about the role of rare, catastrophic events on tropical forest dynamics.
FAUNA OF YOSEMITE NATIONAL PARK LAKES HAS LOW RESISTANCE BUT HIGH RESILIENCE TO FISH INTRODUCTIONS
Authors: Knapp Roland A. , Hawkins Charles P. , Ladau Joshua , McClory Jodi G. 
Published: June 2007

The ratio of the number of taxa observed at a site to that expected to occur in the absence of anthropogenic impacts (O/E) is an ecologically meaningful measure of the degree of faunal alteration. We used O/E ratios to describe the response by amphibian, reptile, benthic macroinvertebrate, and zooplankton taxa in originally fishless lakes in Yosemite National Park to the introduction and subsequent disappearance of nonnative fish. To quantify resistance (the degree to which a system is altered when the environment changes) and resilience (the degree to which a system returns to its previous configuration once the perturbation is removed), we compared O/E ratios between lakes that were never stocked, were previously stocked and still contained fish, or were previously stocked but had reverted to a fishless condition.On average, stocked‐fish‐present sites had 16% fewer taxa than never‐stocked sites (O/E = 0.84 vs. 1.00, respectively). This statistically significant difference in O/E ratios indicates that native fauna had relatively low resistance to fish introductions. Resistance was inversely related to fish density and elevation, and directly related to water depth. Vulnerability to impacts of trout predation differed markedly between faunal groups, being high for amphibians, reptiles, conspicuous benthic invertebrates, and zooplankton and low for inconspicuous benthic invertebrates. O/E ratios in stocked‐now‐fishless sites were significantly higher (1.00) than those in stocked‐fish‐present sites and were not significantly different from those in never‐stocked sites, indicating that this fauna had high resilience. For stocked‐now‐fishless sites, the relationship between the O/E ratio and the number of years since fish disappearance indicated that taxonomic composition recovered to closely resemble that of never‐stocked lakes in less than two years following fish disappearance. Collectively, these results indicate that despite strong effects of an introduced predatory fish on community structure, these systems recover quickly and predictably following fish removal.
POPULATION VIABILITY AND REINTRODUCTION STRATEGIES: A SPATIALLY EXPLICIT LANDSCAPE‐LEVEL APPROACH
Authors: Münzbergová Zuzana , Mildén Mikael , Ehrlén Johan , Herben Tomáš 
Published: June 2007

The effect of habitat destruction on the likelihood of species survival is often estimated based on the assumption that colonization and extinctions are in balance. This assumption is not sustainable in species where the dynamics of colonization and extinctions is slow in relation to landscape changes, such as in most plants.Here we use an alternative approach, a realistic, dynamic landscape‐level model that does not rely on this assumption. It enables estimation of the effect of habitat destruction using field data on the biology of a species and on real landscape structure. Because our approach relies on direct comparisons of changes in population size and survival probability due to habitat changes, it can be easily extended to other conservation questions, such as assessing the effects of events causing the extinction of populations but allowing for recolonization, or identifying optimal reintroduction strategies.We applied this method to a perennial herb, Succisa pratensis, that is a typical grassland species. We combined detailed demographic data with information on the spatial distribution of suitable habitats to model species dynamics in the landscape under different scenarios. The results show that habitat destruction alone has little effect on regional survival. However, the effect of habitat destruction increases when combined with factors causing extinctions of the existing populations that are expected to play a significant role in the study system. Our results further show that an optimal reintroduction strategy at the landscape level depends on the number of available seeds.The approach presented here was designed for studying systems where species colonization–extinction dynamics is slow compared with landscape changes. Such time lags and nonequilibrium dynamics have been suggested to be important features of many ecosystems and life forms, and this approach is thus likely to be useful for a wide range of future studies. The approach also allows the estimation of short‐term effects of habitat destruction, i.e., situations that are nonequilibrium by definition. This is never possible with equilibrium models, giving the model a wide applicability for all types of organisms.
COMMUNITY RELATIONSHIPS OF AVIAN MALARIA PARASITES IN SOUTHERN MISSOURI
Authors: Ricklefs Robert E. , Swanson Bethany L. , Fallon Sylvia M. , MartÍnez-AbraÍn Alejandro , Scheuerlein Alexander , Gray Julia , Latta Steven C. 
Published: June 2007

We studied the organization and temporal stability of an assemblage of malaria parasites (generaPlasmodiumandHaemoproteus) and their passerine avian hosts in a forested study area in southern Missouri, USA, over four years. We detected parasite infections by polymerase chain reaction (PCR) of parasite DNA from host blood samples and identified parasite lineages by sequencing a part of the mitochondrial cytochromebgene. We obtained 757 blood samples from 42 host species. Prevalence of malaria parasitism judged by PCR averaged 38.6% and varied in parallel in the three most abundant host species over the four years of the study. Parasite prevalence bore a U‐shaped relationship to host sample size. Prevalence was weakly positively associated with host body mass, but not with foraging stratum, nest height, nest type, plumage brightness, or sexual dichromatism. Over the sample as a whole, parasite prevalence did not vary between males and females or between hatch‐year and older individuals.We differentiated 34 parasite lineages. The number of host species per lineage varied from one to eight and increased with sample size. We recovered up to 14 lineages of parasite from a single host. Three relatively common lineages in the Ozarks were found nowhere else; four others were recovered from other sites in eastern North America; and six additional well‐sampled lineages were distributed in the Greater Antilles among resident island host species. Parasites that are endemic among native species of hosts on the tropical wintering grounds of Ozark birds were recovered from hatch‐year birds in the Ozarks, indicating that transmission takes place on the summer breeding grounds, and consequently, that suitable vectors are present in both the temperate and tropical portions of the parasite lineage distributions.We estimate that the number of parasite lineages within a local area will approximate the number of host species and that our perception of host breadth and parasite diversity will increase for most lineages and hosts with increased sampling. Thus, host–parasite relationships in a local area, including the role of parasites in sexual selection and the evolutionary maintenance of sex, are likely to be complex, with population and evolutionary dynamics involving many actors.
A Survey of Therapeutic Ultrasound Use by Physical Therapists Who Are Orthopaedic Certified Specialists
Authors: Wong Rita A , Schumann Britta , Townsend Rose , Phelps Crystal A 
Published: June 2007

Background and Purpose
For many years, ultrasound (US) has been a widely used and well-accepted physical therapy modality for the management of musculoskeletal conditions. However, there is a lack of scientific evidence on its effectiveness. This study examined the opinions of physical therapists with advanced competency in orthopedics about the use and perceived clinical importance of US in managing commonly encountered orthopedic impairments.

Subjects
Four hundred fifty-seven physical therapists who were orthopaedic certified specialists from the Northeast/Mid-Atlantic regions of the United States were invited to participate.

Methods
A 77-item survey instrument was developed. After face and content validity were established, the survey instrument was mailed to all subjects. Two hundred seven usable survey questionnaires were returned (response rate=45.3%).

Results
According to the surveys, the respondents indicated that they were likely to use US to decrease soft tissue inflammation (eg, tendinitis, bursitis) (83.6% of the respondents), increase tissue extensibility (70.9%), enhance scar tissue remodeling (68.8%), increase soft tissue healing (52.5%), decrease pain (49.3%), and decrease soft tissue swelling (eg, edema, joint effusion) (35.1%). The respondents used US to deliver medication (phonophoresis) for soft tissue inflammation (54.1%), pain management (22.2%), and soft tissue swelling (19.8%). The study provides summary data of the most frequently chosen machine parameters for duty cycle, intensity, and frequency.

Discussion and Conclusion
Ultrasound continues to be a popular adjunctive modality in orthopedic physical therapy. These findings may help researchers prioritize needs for future research on the clinical effectiveness of US.
FEM calculations of capillary rheometer flow for carbon‐filled liquid crystal polymer composites
Authors: Kunen Emily , Keith Jason M. , Grant Peter W. , King Julia A. , Morrison Faith A. 
Published: June 2007

AbstractThere is an emerging market for conductive resins for use in fuel cell bipolar plates. This research focuses on developing a finite element model of a capillary rheometer. Comsol Multiphysics 3.2b was used to model the flow of a remeltable thermoplastic matrix material, Vectra A950RX Liquid Crystal Polymer, with varying amounts of either a carbon black or synthetic graphite filler, to obtain the velocity profile and pressure drop of these composites within the capillary. Previous experimental results have shown that the molten composites obey a shear‐thinning power law behavior. When comparing the model predicted pressure drops from the model with the experimental data, very good agreement was obtained. This signifies that the rheological behavior of the composites can be described by a power law relationship, using parameters specific to each composite. When comparing the modeled velocity profile with the theoretical profile, it was found for all composite formulations that the velocity becomes fully developed within a length of 0.05 times the diameter of the tube, independent of the power law parameters n and m. This work is a necessary first step in developing 2D or 3D mold filling simulations for fuel cell bipolar plate applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Lichtinduzierte Reaktionen, II. Photochemische Ketenbildung aus cyclischen nichtkonjugierten Ketonen
Authors: Quinkert Gerhard , Blanke Egbert , Homburg Friedhelm 
Published: June 2007

AbstractNichtkonjugierte Ketone liefern bei UV‐ Bestrahlung Carbonsäuren. Intermediär lassen sich spektroskopisch Ketene nachweisen, die mit Wasser Carbonsäuren und mit Cyclohexylamin Säureamide ergeben. Bei UV‐Bestrahlung des cyclischen Ketons II (RCH3, R′R″D) beobachtet man eine intramolekulare Wanderung eines D‐Atoms; die Ketene lassen sich als Disproportionierungs‐produkte eines primär photochemisch erzeugten Alkyl/Acyl‐Biradikals auffassen. Die bei II (RR′R″CH3) und III praktisch ausbleibende Säurebildung wird damit verständlich.
Acyl‐lacton‐Umlagerung, XXXII. Umlagerung von α‐Acyl‐dilactonen
Authors: Korte Friedhelm , Efferoth Hans , Wüsten Florian 
Published: June 2007

AbstractDilactone2−8) reagieren unter den Bedingungen der Esterkondensation nur mit einer Methylengruppe. Dagegen lassen sich Dicarbonsäureester in Gegenwart der doppelten Menge des Kondensationsmittels mit beiden Carbonylgruppe im Verhältnis 1: 2 mit γ ‐Butyrolacton kondensieren. Beide Reaktionsprodukte können zu Tetrahydrofuranderivaten umgelagert werden. Die Umlagerung von α.α′‐Oxalyl‐bis‐butyrolacton in wäßriger Salzsäure/Dioxan führt zum 10‐Oxo‐1.6‐dioxa‐spiro[4.5]decan.
Über Metalltrifluorphosphin‐Komplexe, II. Hexakis(trifluorphosphin)‐ chrom(0) und Tris(trifluorphosphin)‐chrom(0)‐tricarbonyl
Authors: Kruck Thomas 
Published: June 2007

AbstractBei Hochdruckumsetzungen von Trifluorphosphin mit Dibenzolchrom entsteht in einer‐Trockenreaktion kristallines, farbloses Hexakis(trifluorphosphin)‐chrom(0)

equation image

Die flüchtige, diamagnetische Verbindung gleicht in ihrem chemischen und physikalischen Verhalten weitgehend dem Chromhexacarbonyl. Mit Mesitylenchrom(0)‐tricarbonyl und Chromhexacarbonyl bildet Trifluorphosphin Gemische der Verbindungen Cr(PF3)6‐n(CO)n(n⩾3), hingegen liefert Triamminchrom(0)‐tricarbonyl mit Trifluorphosphin unter Druck gemäß

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das ebenfalls farblose, kristalline und äußerst flüchtige Tris(trifluorphosphin)‐ chrom(0)‐tricarbonyl. Nach dem IR‐Spektrum ist für den diamagnetischen Komplex cis‐Stellung der PF3‐Liganden anzunehmen.
Chromatographische Untersuchungen von Äthylestern kondensierter Phosphorsäuren
Authors: Wieker Wolfgang , Walter Hans‐Peter , Thilo Erich 
Published: June 2007

AbstractPapierchromatographisch läßt sich der Langheld‐Ester, das Reaktionsprodukt von P4O10 mit Äther, bei Verwendung eines wasserhaltigen Laufmittels in zehn Komponenten auftrenne, die als Monophosphorsäure, Diphosphorsäure, Monoäthylmono‐, Diäthylmono‐, Monoäthyldi‐, Diäthyldi‐, Triäthyldi‐, Tetraäthyldi‐, Diäthyltri‐ und Triäthyltriphosphat identifiziert wurden. Demnach kann der Langheld‐Ester nicht — wie RÄTZ und THILO zunächst annahmen — nur aus Tetraäthyltetrameta‐ und Tetraäthylisotetrametaphosphat bestehen. Ähnliche Estergemische werden auch bei der Papierchromatographie des vermeintlichen Triäthyltrimetaphosphats und Pentaäthyltriphosphats erhalten.
Synthesen in der heterocyclischen Reihe, VI. Darstellung von 1‐Guanyl‐pyrazol und Pyrazolyl‐(1)‐s‐triazin. — Synthesen substituierter s‐Triazine
Authors: Bredereck Hellmut , Effenberger Franz , Hajek Manfred 
Published: June 2007

AbstractAus Aminoguanidin‐hydrogencarbonat und 1.1.3.3‐Tetraäthoxy‐propan bzw. Propinal entsteht in Gegenwart von Salzsäure 1‐Guanyl‐pyrazol‐hydrochlorid, das mit Aminen unter Aminolyse reagiert und mit Ringschlußkomponenten s‐Triazine liefert. — Die Pyrazolyl‐Gruppe der Pyrazolyl‐(1)‐s‐triazine läßt sich leicht gegen nucleophile Agentien austauschen; hierbei wurde erstmals das Hydroxy‐s‐triazin (als Monohydrat) isoliert.
Zoobenthos of Lake Uluabat, a Ramsar Site in Turkey, and Their Relationship with Environmental Variables
Authors: Kökmen Seval , Arslan Naime , Filik Cansu , Yilmaz Veysel 
Published: June 2007

AbstractThe numerical and proportional distributions of zoobenthos in lake Uluabat, which is located in the Northwestern part of Turkey and having international importance according to the Ramsar Convention, were determined from August 2004 to July 2005 at monthly intervals (except for December 2004, January and February 2005) at 12 different stations. Thirty‐three taxonomic groups were recorded. It was found that the zoobenthos consisted of 35.6 % Oligochaeta, 27.7 % Nematoda, 12.3 % Chironomidae larvae, 10.7 % Gastropoda, 3.6 % Ostracoda, and 10.1 % Varia by numbers (Bivalvia, Ceratopogonidae, Hirudinea, Odonata, Ephemeroptera, Asilidae, Hydraacarina, Hemiptera, Argulidae, and Gammaridae). The average number of invertebrates was 160 individuals for 33 taxa at the 12 different stations. Also some environmental parameters of the lakewater were analyzed (temperature, pH, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, NO2–N, NO3–N, NH3–N, PO4–3, fecal coliform, and total coliform). The relationships between the dynamics of the Oligochaeta and the physicochemical variables were supported by the Pearson correlation index and the canonical correspondence analysis (CANOCO). It was found that the relation between the average number of P. hammoniensis and P. albicola (p < 0.05, r = 0.590 and 0.593, respectively) and L. hoffmeisteri (p < 0.01, r = 0.777) was directly proportional while the relation between the average number of some taxa Trichodrillus sp., Rhyacodrilus coccineus, Nais communis, N. variabilis, and N. barbata and NO3–N (p < 0.05, r = –0.685) was inversely proportional.
Alternative Mechanistic Paths in the Hetero‐Diels–Alder Reaction of α‐Oxothiones: A Theoretical Study
Authors: Legnani Laura , Lunghi Carlotta , Albini Franca Marinone , Nativi Cristina , Richichi Barbara , Toma Lucio 
Published: June 2007

AbstractDFT calculations at the B3LYP/6‐311+G(d,p) level for the C, H, and O atoms and at the 6‐311+G(2df,p) level for the S atom were used to study the hetero‐Diels–Alder reactions between several α‐oxothiones and ethylene or methyl vinyl ether (MVE). All the transition states and the intermediates along the reaction pathways, as well as the reaction products, were located. The reactions with ethylene are all concerted though asynchronous whereas in the reactions with MVE the electron‐releasing character of the methoxy substituent lowers the energy barriers and enhances the asynchronicity and the charge transfer process to such an extent that the reaction may become unconcerted and exhibit a two‐step mechanism with a zwitterionic intermediate derived from nucleophilic attack of electron‐rich MVE to the sulfur atom of the strongly electrophilically activated α‐oxothiones. The reactions are also favored by the conjugation of the newly formed C=C bond. Moreover, the geometric features of the diene exert a nonnegligible role, as dienes that are planar or almost planar in their ground state show a lower energy barrier. Thus, both geometric and electronic features of the dienes as well as of the dienophiles play a significant role in the easiness of the reactions and in their mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)