bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Nutrient Concentrations in the River Elbe
Authors: Guhr Helmut , Spott Dieter , Bormki Gerald , Baborowski Martina , Karrasch Bernhard 
Published: February 2004

AbstractThe nutrient turnover and the resulting development of phytoplankton biomass were investigated during four river surveys in the free‐flowing reach of the river Elbe under almost constant hydrological and meteorological conditions taking into account the transport time and the time of day. The chlorophyll‐a concentration was found to increase by a factor of between 3 and 6 depending on the season, while the biomass load increased by a factor of up to 18. The concentrations of dissolved silicate and dissolved total phosphate behaved oppositely to this development, while the levels of particulate bound nutrients rose accordingly. Depending on the season, 6…23% of the total bound nitrogen was found to be removed from the river by denitrification. The river Saale contains the highest load of nutrients of all the tributaries. At the end of the investigated reach, algae biomass accounts for as much as 75% of the POC.
Extracellular Enzyme Activity in the River Elbe during a Spring Flood Event
Authors: Karrasch Bernhard , Bormki Gerald , Herzsprung Peter , Winkler Markus , Baborowski Martina 
Published: February 2004

AbstractThe ecological balance of rivers can be significantly disturbed by floods, increasing the supply of allochthonous material and energy to the fluvial planktonic food web. During spring flooding in the Elbe in 1999, various physicochemical (pH, conductivity, suspended particulate matter (SPM), particulate and dissolved organic carbon (DOC, POC), inorganic nutrients) and biological parameters (concentration of chlorophyll‐a, abundance and biomass of bacteria) were studied in connection with the microbial self‐cleaning capacity (dissolved and particle‐associated extracellular enzyme activity of ten different enzymes). The pattern of dissolved and particulate material was found to differ greatly (regarding dilution and allochthonous input dynamics), with biological parameters displaying partly differing patterns owing to their bioactivity. Hydrolytic activity was detected for all the enzyme categories investigated, with especially high breakdown rates being determined for proteins containing leucine, arginine, and tyrosine. The overall activities of all the microbial extracellular enzymes studied proved to be dominated by the ectoenzymes ((62.8 ± 13.6)%) associated with particulate (particles, aggregates, and bacterial cell walls). The resulting ecological implications for microbial self‐cleaning processes in rivers are discussed.
Free and Particle‐associated Extracellular Enzyme Activity and Bacterial Production in the Lower Elbe Estuary, Germany
Authors: Karrasch Bernhard , Ullrich Sören , Mehrens Maren , Zimmermann‐Timm Heike 
Published: February 2004

AbstractA high abundance of particles and aggregates is a characteristic of estuaries and may represent important loci of increased bioproductivity and microbial activity. From a survey performed in the Elbe estuary, particle concentration (using a particle counter), bacterial biomass and abundance (AODC method), bacterial production rates ([3H] thymidine method) and the microbial extracellular enzyme activity of 11 enzymes (MUF and MCA method) were determined with particular respect to their relationship to particles and aggregates (sizefractionated). Although higher particle abundance was found compared to other sections of the river Elbe, neither relative nor absolute bacterial activity associated with particles and aggregates was enhanced. The activity of free dissolved microbial enzymes was found to dominate the breakdown of organic material. The productivity of free dispersed bacteria ≥0.2…<2 μm (2…69%) and bacteria attached to small particles ≥2…<10 μm (27…93%) considerably surpassed that of bacteria associated with particles >10 μm (0…40%). This indicates that the larger particles and aggregates do not always contribute substantially to the overall microbial activity in rivers and estuaries.
The Situation of the German Elbe Tributaries — Development of the Loads in the Last 10 Years
Authors: Kowalik Corinna , Kraft Jörg , Einax Jürgen W. 
Published: February 2004

AbstractFrom 1991 to 1996 intensive investigations (“Leitprojekt Elbe 2000”) were performed on the water and sediment quality of the German Elbe tributaries. Schwarze Elster, the Mulde river system (Freiberger Mulde, Zwickauer Mulde, andVereinigte Mulde), Saale and its tributaries Ilm and Unstrut, Weiße Elster, and Havel and Spree were considered. These important tributaries have a catchment area of approximately 86 000 km2 and they are together more than 2 500 km long.The concentrations of different metals (e.g., Cd, Cr, Cu, Fe, Hg, Pb, or Zn) were determined. Furthermore, the alkali and alkaline earth elements and the concentrations of anions such as Cl—, NO, and SO were analyzed in the water samples. In addition, conductivity, pH, redox potential, and temperature were measured directly at the sampling location. Together 21 700 pieces of data for water samples and 8 300 pieces of data for sediment samples formed the base for the statistical evaluation and interpretation.The water samples of the German Elbe tributaries are characterized by high salt loads (Ca, Mg, Na, Cl—, and conductivity), resulting from mining in the southern Harz region. In the sediments the concentrations of As, Cd, Pb, and Zn were identified as the most important anthropogenic parameters. The elements Co, Fe, Mn, and Ni were detected as typical background elements.
Saliva sampling to assess cortisol levels in unrestrained common marmosets and the effect of behavioral stress
Authors: Cross N. , Pines M.K. , Rogers L.J. 
Published: February 2004

AbstractWe report a method for taking saliva samples from unrestrained, captive marmosets (Callithrix jacchus) to assess levels of free cortisol. Saliva samples can be obtained reliably, without any habituation, by encouraging the marmosets to lick and chew a cotton‐wool bud coated in banana. Saliva is thus left on the bud. We also tested sweetened fruit‐drink crystals and a number of other substances, but none of these attracted all of the marmosets, and even flavors that were effective once soon lost their attraction. The presence of banana in the samples collected was found to lower the measured concentration of cortisol; however, as shown in samples taken with and without the banana coating on the bud, it did so in a linear and consistent way, and did not vary significantly among subjects. Therefore, a simple conversion factor could be applied to correct for the presence of banana. A first experiment showed that the marmosets exhibited a rise in salivary cortisol levels in response to social isolation. A second experiment showed elevation of cortisol during a period when the marmosets were disturbed by increased human activity and noise levels in the building in which they were housed. Hence, this method of saliva sampling is a convenient, noninvasive means of assessing cortisol levels in marmosets. Am. J. Primatol. 62:107–114, 2004. © 2004 Wiley‐Liss, Inc.
Predicting folivorous primate abundance: Validation of a nutritional model
Authors: Chapman Colin A. , Chapman Lauren J. , Naughton‐Treves Lisa , Lawes Michael J. , Mcdowell Lee R. 
Published: February 2004

AbstractUnderstanding the determinants of animal abundance has become more vital as ecologists are increasingly asked to apply their knowledge to the construction of informed management plans. However, there are few general models are available to explain variation in abundance. Some notable exceptions are studies of folivorous primates, in which the protein‐to‐fiber ratio of foods has been shown to predict biomass. Here we examine the generality of Milton's [American Naturalist 114:363–378, 1979] protein/fiber model by providing a detailed analysis of diet selection in black‐and‐white colobus monkeys (Colobus guereza), and applying the model to populations shown to be stable; an assumption not previously examined. Based on observations of two groups of black‐and‐white colobus in Kibale National Park, Uganda, and one group in a forest fragment, we documented that the animals selected young leaves that had more protein, were more digestible, and had a higher protein‐to‐fiber ratio than mature leaves. The mature leaves did not differ from young leaves with respect to secondary compounds or mineral content (with the exceptions of copper and zinc). All of the colobus groups selected foods with a high protein‐to‐fiber ratios. However, one group also selected more digestible foods, and in another group, foraging efforts were positively related to zinc and negatively related to potassium. Previous studies that examined Milton's protein/fiber model did not demonstrate that the study populations were stable. If some populations were not at carrying capacity, then the correlations drawn between food availability and/or quality and folivore biomass may have been spurious. To address this issue, we censused a series of forest fragments in 1995 and again in 2000. We found that the populations in these fragments had declined from 165 in 1995 to 119 animals in 2000. However, based on evidence of population stability and lack of forest disturbance, we concluded that five of the original populations were stable. The biomass of these populations was related to the protein‐to‐fiber ratio of the fragment's trees. Combining our data with published data, we demonstrate that the protein‐to‐fiber ratios of mature leaves available to these folivorous primates accounted for 87% of the variance in their biomass. Am. J. Primatol. 62:55‐69, 2004. © 2004 Wiley‐Liss, Inc.
Dietary patterns in Perrier's sifakas (Propithecus diadema perrieri): A preliminary study
Authors: Lehman Shawn M. , Mayor Mireya 
Published: February 2004

AbstractSome lemur species range into only one habitat type, whereas others range into a variety of habitats. Because plant community structure can differ between habitats, dietary patterns may vary for conspecific groups of primates that range into more than one type of habitat. The goal of our study was to determine how habitat variation influences dietary patterns in Perrier's sifakas (Propithecus diadema perrieri) that range into both dry and riparian forests in northern Madagascar. We collected 542 hr of data on the behavior and diet of two groups of P.d. perrieri from 7 June to 4 August 1998 at Camp Antobiratsy in Analamera Special Reserve, Madagascar. We computed indices of dietary diversity for each group and dietary/plant species similarity between groups. P.d. perrieri in group 1 fed predominantly in dry forest (72.7% of feeding records, n=660), whereas those in group 2 fed most often in riparian forest (73.7% of feeding records, n=666). The index of dietary similarity (0.986) was significantly higher than the index of plant species similarity (0.767). Although the P.d. perrieri in the two study groups fed predominantly in different forest habitats, they ate similar food items in very comparable proportions (but not from the same plant species). However, based on habitat availability measures, neither group fed where they were expected to feed. Am. J. Primatol. 62:115‐122, 2004. © 2004 Wiley‐Liss, Inc.
Prevalence of enteric parasites in pet macaques in Sulawesi, Indonesia
Authors: Jones‐Engel Lisa , Engel Gregory A. , Schillaci Michael A. , Froehlich Jeffery , Paputungan Umar , Kyes Randall C. 
Published: February 2004

AbstractOn the Indonesian island of Sulawesi, nonhuman primate pets come into frequent contact with humans, presenting the possibility of zoonotic and anthropozoonotic disease transmission. We collected fecal samples from 88 pet macaques representing six of the seven macaque species currently recognized as endemic to Sulawesi (Macaca nigra, M. nigrescens, M. hecki, M. tonkeana, M. maura, andM. ochreata) as well as two non‐endemic species (M. fascicularisandM. nemestrina) in order to determine the prevalence of intestinal parasitic infection in this population. Seven taxa of intestinal protozoa (Blastocystis hominis, Iodamoeba bütschlii, Entamoeba coli, Entamoeba hartmanni, Chilomastrix mesnili, Endolimax nana, andRetortamonas intestinalis) and three taxa of nematodes (hookworm,Trichurisspp., andAscarisspp.) were detected. The overall parasitization rate was 59.1%. Commensal organisms predominated in this population. Parasitization was not statistically correlated with macaque age group, sex, species, or location, or with the owner's level of education. These findings are discussed in the context of primate pet ownership practices in Sulawesi. Am. J. Primatol. 62:71‐82, 2004. © 2004 Wiley‐Liss, Inc.
Relations among birth condition, maternal condition, and postnatal growth in captive common marmoset monkeys (Callithrix jacchus)
Authors: Tardif Suzette D. , Bales Karen L. 
Published: February 2004

AbstractThe present study characterizes the relations among maternal condition, litter size, birth condition, and growth in body weight for a population of common marmosets. The subjects of the study were marmosets born into a single colony between 1994 and 2001. Three sets of analyses were conducted to answer the following questions: 1) Is there a relationship between litter size, maternal condition, and birth condition? In the study population, maternal body weight, maternal age, litter size, and birth condition were related in a complex fashion. Birth weight and prenatal long‐bone growth, as reflected in knee–heel length, were both related to maternal age, with older mothers supporting higher prenatal growth. Age and maternal condition appeared to interact as determinants of long‐bone growth, as the combination of older and larger mothers resulted in significantly longer knee–heel lengths in their offspring. 2) Is there a relationship between birth condition or maternal condition and subsequent growth or final adult size? The early growth rate in this population was similar to early growth rates reported for three different marmoset colonies, suggesting that early growth may be relatively inflexible in this species. However, within this population, the variation that did occur in early growth rate was related to birth weight and maternal weight. Later growth and adult weight were related to birth weight and litter size: small twin infants displayed slower later growth rates and were smaller as adults than twins that began life at a higher birth weight, while the birth weight of triplets was not related to adult size. In these marmosets, small infants that were the result of increased litter size differed from small infants whose small birth size resulted from other factors. This reinforces the proposal that the causes of low birth weight will be relevant to the development of the marmoset as a model of prenatal environmental effects. Am. J. Primatol. 62:83–94, 2004. © 2004 Wiley‐Liss, Inc.
Sexual behavior and hormonal estrus cycles in captive aged lowland gorillas (gorilla gorilla)
Authors: Atsalis Sylvia , Margulis Susan W. , Bellem Astrid , Wielebnowski Nadja 
Published: February 2004

AbstractTo evaluate whether observed cycles in proceptive behavior in aging lowland gorilla females (age 40+) at Brookfield Zoo were driven by ovarian activity, we compared monthly behavioral data to estradiol and progestogen cycles based on fecal hormone assessments. Progestogen peaks showed regularity and close coincidence with monthly sexual behaviors. Estradiol was more variable. Progestogen peaks varied between 22±5 days for the control female (29 years old), to 24±2.5 and 29±8 for the two aged subjects. In the first aged female, which was housed with other females and a silverback, the high degree of cyclicity in sexual behavior, regularity of progestogen cycles, and close concordance between hormonal cycling and sexual behavior strongly compared to patterns found (in this and other studies) in gorilla females <35 years old. Cyclical progestogen peaks were longer and more variable in the second aged female—perhaps because she lacked the social mediation of other females or a male. For husbandry reasons she is not housed with the gorilla group, behavioral data were not collected from her. The value of our longitudinal study is in obtaining reproductive profiles of primate females that are approaching maximum lifespan. This pilot study is part of a larger research project on reproductive senescence that will include other captive females >35 years old, a population that is rapidly increasing in North American zoos as gorillas continue to age. Am. J. Primatol. © 2004 Wiley‐Liss, Inc.
Scalp EEG for the diagnosis of epilepsy and photosensitivity in the baboon
Authors: Ákos Szabó C. , Leland Michelle , Sztonák László , Restrepo Santiago , Haines Richard , Mahaney Michael A. , Williams Jeff T. 
Published: February 2004

AbstractSpontaneous seizures have been observed in several baboon species housed at the Southwest National Primate Research Center (SNPRC), including Papio hamadryas anubis and cynocephalus/anubis, hamadryas/anubis, and papio/anubis hybrids. The goal of this study was to establish a noninvasive, reliable electroencephalographic technique to characterize epilepsy phenotypes and assess photosensitivity in these subspecies. Thirty baboons with witnessed seizures, and 15 asymptomatic baboons underwent scalp electroencephalograms (EEGs) with photic stimulation (PS). The sensitivity and specificity of surface EEG for identifying interictal epileptic discharges (IEDs) in baboons with witnessed seizures were examined. The morphology of IEDs, electroclinical features of seizures and responses to PS, reproducibility of EEG findings, and intrarater reliability were also evaluated. Twenty‐three seizure baboons (77%) demonstrated IEDs, predominantly with frequencies of 4–6 Hz in 18 baboons and 2–3 Hz in six baboons. Two seizure animals had a mixture of 2–3‐Hz and 4–6‐Hz IEDs. All animals with 2–3‐Hz IEDs were 3 years old or younger. Myoclonic seizures (MS) and generalized tonic‐clonic seizures (GTCS) were recorded in 13 baboons (43%). PS activated IEDs in 15 baboons (50%) and seizures in nine baboons. The presence of IEDs or seizures was not associated with a particular gender or species (Fisher exact test, α=0.05). Seizures were more common in animals >3 years old, while PS‐induced IEDs and seizures were more prevalent in P.h. anubis/cynocephalus crosses compared to P.h. anubis. In the asymptomatic controls, IEDs were recorded in five baboons (33%), and photoparoxysmal responses were observed in two (13%). Surface EEG is a sensitive and reliable instrument for characterizing the epilepsy encountered in Papio species. Electroclinically, the seizure animals had generalized epilepsy with photosensitivity. The variation in IED morphology may be age‐related or it may reflect different epileptic phenotypes. Ketamine provoked IEDs and seizures in most seizure animals and only in a few asymptomatic baboons; therefore, it may enhance the sensitivity of surface EEG for detecting a predisposition to epilepsy. Am. J. Primatol. 62:95–106, 2004. © 2004 Wiley‐Liss, Inc.
Nature or Petrochemistry?—Biologically Degradable Materials
Authors: Mecking Stefan 
Published: February 2004

AbstractNaturally occurring polymers have been utilized for a long time as materials, however, their application as plastics has been restricted because of their limited thermoplastic processability. Recently, the microbial synthesis of polyesters directly from carbohydrate sources has attracted considerable attention. The industrial‐scale production of poly(lactic acid) from lactic acid generated by fermentation now provides a renewable resources‐based polyester as a commodity plastic for the first time. The biodegradability of a given material is independent of its origin, and biodegradable plastics can equally well be prepared from fossil fuel feedstocks. A consideration of the overall carbon dioxide emissions and consumption of non‐renewable resources over the entire life‐cycle of a product is not necessarily favorable for plastics based on renewable resources with current technology—in addition to the feedstocks for the synthesis of the polymer materials, the feedstock for generation of the overall energy required for production and processing is decisive.
Monohydroxy‐hydrazone‐functionalized thermally crosslinked polymers for nonlinear optics
Authors: Singh Rajendra K. , Stoffer James O. , Flaim Tony D. , Hall David B. , Torkelson John M. 
Published: February 2004

AbstractThe synthesis and properties of six hydrazone‐functionalized crosslinked polymers possessing stable nonlinear optics (NLO) properties are presented. First, a series of six hydroxy‐functionalized, NLO‐active hydrazone chromophores were synthesized. These chromophores were then grafted via its hydroxy functionality on an epoxy polymer to obtain the six NLO‐active soluble prepolymers. The grafting reaction yielded multiple secondary hydroxyl sites, which were used for further crosslinking by formulation of the prepolymer with a blocked polyisocyanate crosslinker. This formulation was spin‐coated on glass slides to form 2–2.5 μ thick defect‐free transparent films. The films were corona‐poled above their glass‐transition temperatures to align the chromophores in a noncentrosymmetric fashion and were simultaneously cured. The thermal characteristics of the second‐order nonlinearity of the six polymers were compared to illustrate the key structure–property relationships underlying the performance of the films in terms of NLO activity and thermal stability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 770–781, 2004
Properties of amine‐containing coatings prepared by plasma polymerization
Authors: Choukourov A. , Biederman H. , Kholodkov I. , Slavinska D. , Trchova M. , Hollander A. 
Published: February 2004

AbstractTwo monomers, ethylenediamine (EDA) and diaminocyclohexane (DACH), were plasma‐polymerized in continuous‐wave (CW) and pulse modes. The influence of different plasma parameters on the deposition rate and film composition were investigated in detail and the changes in aminofunctionalization with varying pulse parameters were examined by FTIR, ESCA, and chemical‐derivatization techniques. It was shown that a varying duty cycle does not produce a considerable effect on the retention of amine groups into the film, while power and ton play a significant role in the polymerization process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 979–990, 2004