bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonant Raman spectroscopy of confined and surface phonons in CdSe‐capped CdS nanoparticles
Authors: Dzhagan Volodymyr , Rayevskaya Olexandra , Stroyuk Olexandr , Kuchmiy Stepan , Zahn Dietrich R. T.
Published: July 2009

A series of colloidal CdS/CdSe heteronanoparticles are studied by Resonant Raman spectroscopy. The Raman‐active phonons of both CdS‐core and CdSe‐shell are monitored upon a gradual increase of the shell thickness. Noticeable differences between the Raman spectra taken at different excitation wavelengths are observed, which can be related to different resonant conditions for different vibrational modes at a certain excitation wavelength. The possible morphology transformation of the CdSe shell with increase of its thickness is discussed, based on the correlation between changes in phonon spectra of the nanoparticles and the spectra of photoluminescence and optical absorption. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum tunneling through moving Kondo objects
Authors: Kikoin Konstantin , Kiselev Michael N. , Richert Jean
Published: July 2009

We show how the time‐dependent modulation of charge input signal applied to the gate electrode in a double quantum dot may be converted to a pulse in the Kondo tunneling current, which is predominantly spin response of this nano‐device in a strong Coulomb blockade regime. The stochastic component of the input signal reveals itself as the infrared cutoff of Kondo tunneling transmission (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phononic crystals and manipulation of sound
Authors: Pennec Yan , Djafari‐Rouhani Bahram , Larabi Hocine , Vasseur Jérôme , Hladky‐Hennion Anne‐Christine
Published: July 2009

The acoustic properties of phononic crystals are presented, using numerical simulations. In a first part we study some possible applications of these composite materials. In particular, we show that defect modes (cavities, wave guides, stubs...) inserted inside the 2D periodic structure may lead to the possibility of manipulating the propagation of sound and realizing selective frequency filters and efficient devices for wavelength demultiplexing. We also report on the vibration modes of a 2D plate, i.e. a phononic crystal of finite thickness along the axis of the inclusions. We investigate the existence of absolute band gaps in the band structure of the plate, either free or deposited on a substrate. This should open new perspectives in the field of high‐frequency radiofrequency devices. Finally, we present the possibility of devicing sonic insulators for frequencies of the order of kHz with relatively small thicknesses of the phononic crystal sample as compared to the wavelength. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Additional phonon modes related to intrinsic defects in CdHgTe
Authors: Polit J. , Sheregii E. M. , Cebulski J. , Kisiel A. , Marcelli A. , Robouch B. V. , Guidi M. Cestelli , Piccinini M. , Mycielski A.
Published: July 2009

The optical reflectivity measurements data are reported. They were obtained by means of synchrotron (DAFNE‐LIGHT in LNF, Italy) as the radiation source as well as mercury lamp, in far infrared region for the 9 sample of Hg1‐xCdxTe (x = 0.06‐0.7) in the temperature interval 20 K‐293 K. The imaginary part of dielectric function obtained by means of Kramers‐Kroning transformation were analyzed in the Lorentzian‐approximation of dielectric function, using the model of deformed tetrahedra. Beside eight canonical phonon modes observed earlier by Kozyrev et al., we observed several additional lines in the region below 120 cm–1. Our analysis is based on the experimental data obtained for the samples of n ‐ and p ‐type and prepared by different manufacture technologies. The temperature dependence of the frequency of vibration modes in the region 90 cm–1–118 cm–1 is also presented and discussed. This analysis has shown that two kinds of lines are observed in this region: the lines of the first type are generated by the electron transitions while the lines of the second one are generated by oscillations in defect‐bearing tetrahedra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extended van Hove singularity, strong electron–phonon interaction and superconducting gap in doped Bi‐2212 single crystals
Authors: Ponomarev Yaroslav , Mikheev Mikhail , Sudakova Marina , Tchesnokov Sergei , Kuzmichev Svetoslav
Published: July 2009

Tunneling spectroscopy studies of high‐temperature superconductors (HTSC) are overviewed. Facts are presented evidencing the strong electron–phonon interaction and the scaling of a superconducting gap and a critical temperature in doped Bi‐2212 single crystals. A sharp extra structure in the current‐voltage characteristics (CVC's) of Bi‐2212 contacts is attributed to the presence of the extended van Hove singularity (EVHS) close to the Fermi level in slightly overdoped and slightly underdoped samples. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The correlated and shared gamma frailty model for bivariate current status data: An illustration for cross‐sectional serological data
Authors: Hens N. , Wienke A. , Aerts M. , Molenberghs G.
Published: July 2009

Frailty models are often used to study the individual heterogeneity in multivariate survival analysis. Whereas the shared frailty model is widely applied, the correlated frailty model has gained attention because it elevates the restriction of unobserved factors to act similar within clusters. Estimating frailty models is not straightforward due to various types of censoring. In this paper, we study the behavior of the bivariate‐correlated gamma frailty model for type I interval‐censored data, better known as current status data. We show that applying a shared rather than a correlated frailty model to cross‐sectionally collected serological data on hepatitis A and B leads to biased estimates for the baseline hazard and variance parameters. Copyright © 2009 John Wiley & Sons, Ltd.
Colorimetric Protein Sensing by Controlled Assembly of Gold Nanoparticles Functionalized with Synthetic Receptors
Authors: Aili Daniel , Selegård Robert , Baltzer Lars , Enander Karin , Liedberg Bo
Published: July 2009

A novel strategy is described for the colorimetric sensing of proteins, based on polypeptide‐functionalized gold nanoparticles. Recognition is accomplished using a polypeptide sensor scaffold designed to specifically bind to the model analyte, human carbonic anhydrase II (HCAII). The extent of particle aggregation, induced by the Zn2+‐triggered dimerization and folding of a second polypeptide also present on the surface of the gold nanoparticle, gives a readily detectable colorimetric shift that is dependent on the concentration of the target protein. In the absence of HCAII, particle aggregation results in a major redshift of the plasmon peak, whereas analyte binding prevented the formation of dense aggregates, significantly reducing the magnitude of the redshift. The versatility of the technique is demonstrated using a second model system based on the recognition of a peptide sequence from the tobacco mosaic virus coat protein (TMVP) by a recombinant antibody fragment (Fab57P). Concentrations down to ≈10 nM and ≈25 nM are detected for HCAII and Fab57P, respectively. This strategy is proposed as a generic platform for robust and specific protein analysis that can be further developed to monitor a wide range of target proteins.
Fibroblastic Colony-Forming Unit Bone Marrow Cells Delay Progression to Gastric Dysplasia in aHelicobacterModel of Gastric Tumorigenesis
Authors: Wang Sophie S.W. , Asfaha Samuel , Okumura Tomoyuki , Betz Kelly S. , Muthupalani Sureshkumar , Rogers Arlin B. , Tu Shuiping , Takaishi Shigeo , Jin Guangchun , Yang Xiangdong , Wu Deng-Chyang , Fox James G. , Wang Timothy C.
Published: July 2009

Bone marrow mesenchymal stem cells (MSCs) have been shown to have immune modulatory effects. Despite efforts to identify these cells in vivo, to date, MSCs have been defined mainly by their in vitro cell characteristics. Here, we show that Lin−CD44hiSca1−cKit+CD34− cells make up ∼0.5%–1% of murine whole bone marrow cells and yield nearly an equal amount of fibroblastic colony-forming units (CFU-F) as whole bone marrow. After transplantation into lethally irradiated recipients, Lin−CD44hiSca1−cKit+CD34− cells engrafted in the bone marrow long-term and demonstrated characteristics of MSCs, including capacity to differentiate into osteoblasts and adipocytes. To examine whether Lin−CD44hiSca1−cKit+CD34− cells have immune modulatory effects, in vitro coculture with activated CD4+ T-cells resulted in decreased Th17 cell differentiation by Lin−CD44hiSca1−cKit+CD34− cells. Furthermore, serial infusions with Lin−CD44hiSca1−cKit+CD34− cells reduced the progression to low-grade gastric dysplasia in mice infected with chronic Helicobacter felis (p = .038). This correlated with reduced gastric interleukin (IL)-17F, IL-22, and ROR-γt gene expression in responding mice (p < .05). These data suggest that bone marrow derived Lin−CD44hiSca1−cKit+CD34− cells have characteristics of MSCs and reduce progression of early gastric tumorigenesis induced by chronic H. felis infection. The prevention of dysplastic changes may occur through inhibition of Th17-dependent pathways.

Disclosure of potential conflicts of interest is found at the end of this article.
Evaluation of the Long-Term Reconstituting Subset of Hematopoietic Stem Cells with CD150
Authors: Papathanasiou Peter , Attema Joanne L. , Karsunky Holger , Xu Jian , Smale Stephen T. , Weissman Irving L.
Published: July 2009

Blood is a tissue with a high cell turnover rate that is constantly being replenished by bone marrow hematopoietic stem cells (HSCs) seeded during fetal ontogeny from the liver. Here we show that the long-term (LT) reconstituting subset of cKit+Thy1.1(lo)Lin(−/lo)Sca1+Flk2− HSCs is CD150+. HSCs sourced from the fetal liver show LT, multilineage engraftment from E14.5 onward, and the CD150 cell surface molecule can readily substitute Thy1.1 as a positive marker of LT-HSCs in this tissue. From both fetal liver and adult bone marrow, cKit+Thy1.1(lo)Lin(−/lo)Sca1+Flk2− CD150+ cells exhibit robust LT competitive engraftment, self-renewal, multilineage differentiation capacity, and an accessible chromatin configuration consistent with high expression of erythroid/megakaryoid genes in purified cell subsets. Our data show that, with appropriate combinations of cell surface markers, stem cells can be accurately isolated to high purity and characterized. This is important for the clarification of lineage relationships and the identification of bona fide regulators of stem cell self-renewal and differentiation both in normal and neoplastic tissues.
Haematocolpos following herbal treatment for fibroids
Authors: Maharajan Pushpakala Ajaya , Carey Matthew , Agboola Niyi
Published: July 2009

The authors present a case history of a woman of African origin who was found to have a gross haematocolpos and uterine fibroids following investigations for severe abdominal pain. This case highlights the importance, when treating a culturally diverse population, of recognising how practices conducted in other countries might contribute to a presenting condition. Copyright © 2009 Wiley Interface Ltd
Two‐ and Three‐Dimensional Hybrid Compounds Formed by 1,2‐, 1,3‐ and 1,4‐Cyclohexanedicarboxylates of Zinc
Authors: Ramakrishna Matte H. S. S. , Swain Sarat K. , Thirumurugan A. , Rao C. N. R.
Published: July 2009

By employing the hydrothermal method, five zinc cyclohexanedicarboxylates (CHDCs) with the compositions, [Zn2(1,4‐CHDC)(1,10‐phen)4]·(H2O)2(NO3)2 (I), [Zn(1,4‐CHDC)] (II), [Zn3(1,3‐CHDC)3(4,4′‐bipy)] (III), [Zn5(OH)2(1,3‐CHDC)4] (IV), and [Zn(1,2‐CHDC)] (V), were prepared and characterised. Compound I is a molecular structure while II, III and V have two‐dimensional layered structures. Compounds II, III and V are coordination polymers (I0O2) possessing zero‐dimensional inorganic connectivity (In, n = 0) and two‐dimensional organic connectivity (Om, m = 2). Compound IV is a coordination polymer (I0O3) possessing zero‐dimensional inorganic connectivity (In, n = 0) and three‐dimensional organic connectivity (Om, m = 3). In all these compounds, the CHDC anions are in the (e,e) conformation except in II, where it has the (a,e) conformation.
Umweltchemie und Ökotoxikologie in Deutschland
Authors: Lammel Gerhard , Scheringer Martin , Fischer Klaus
Published: July 2009

Fragestellung Wie gestaltet und ggf. verändert sich die wissenschaftliche Produktivität der Umweltchemie und Ökotoxikologie in Deutschland? So einfach die Frage klingt: Sie ist schwer zu beantworten, denn auf Fachgebieten, die per se interdisziplinär sind, sind Überlappungen zu Nachbargebieten die Regel und Abgrenzungen schwierig, zum Teil unmöglich, weil in der Literatur nicht erkennbar oder nicht erfasst. Umweltchemie und Ökotoxikologie sind oft „drin“, stehen aber nicht „drauf“ – auf den Institutsnamen, den Projekttiteln oder den Zeitschriftentiteln. Bei in hohem Maße interdisziplinären Arbeiten – Tendenz steigend – sind wir Wissenschaftler in manchen Fällen sogar selbst verlegen um eine abgrenzende Zuordnung oder empfänden eine solche als inadäquat oder artifiziell.

Ansatz Der Vorstand der Fachgruppe hat die bibliometrische Analyse anhand von Zeitschriftenstichproben als eine probate Herangehensweise für diese Frage gewählt. Nicht erfasst werden in einer solchen Stichprobe Arbeiten, die in Zeitschriften veröffentlicht wurden, die primär nicht der Umweltchemie oder Ökotoxikologie, sondern einem anderen Fach zugerechnet werden. Von der Analyse erfasst werden insbesondere aber die vielen umweltchemischen und ökotoxikologischen Arbeiten von Wissenschaftlern, deren Arbeitsschwerpunkt in einem anderen Feld liegt und die nur gelegentlich auf unseren Gebieten arbeiten, gleich welche Berufs- und Institutsbezeichnung sie tragen mögen. Diese Fehlerquelle zu vermeiden, erscheint für relative junge Fächer und stark interdisziplinäre Arbeitsgebiete prioritär.
Risk factors for obstetric fistula in the Far North Province of Cameroon
Authors: Tebeu Pierre Marie , de Bernis Luc , Doh Anderson Sama , Rochat Charles Henry , Delvaux Thérèse
Published: July 2009

Objective

To describe the circumstances of occurrence and identify potential risk factors for obstetric fistula in northern Cameroon.

Methods

A case series study of 42 obstetric fistula patients seeking services at the Provincial Hospital of Maroua, Cameroon, between May 2005 and August 2007. Structured interviews were conducted prior to surgical intervention.

Results

Among obstetric fistula patients, 60% had lived with obstetric fistula for more than 5 years at the time of surgery. Eighty‐one percent of patients had received no formal education and 86% were teenagers at their first delivery. Regarding the pregnancy and delivery preceding the occurrence of the fistula, 50% of women reported that they had received no prenatal care and 76% were in labor for more than 12 hours. The majority (83%) of women delivered a stillborn baby.

Conclusions

Obstetric fistula patients in the Far North Province of Cameroon had a low level of education, were married at a young age, and had poor access to quality maternal healthcare services.
The role of exploratory buying behavior tendencies in choices made for others
Authors: Chowdhury Tilottama G. , Ratneshwar S. , Desai Kalpesh Kaushik
Published: July 2009

We examine whether the consumer trait of exploratory buying behavior tendencies (EBBT; Baumgartner, H., and Steenkamp, J.E.M. (1996). Exploratory consumer buying behavior: Conceptualization and measurement. International Journal of Research in Marketing, 13, 121–137.) can influence even choices made for others. The results of three experiments in a gift‐giving context show that high (vs. low) EBBT individuals have greater salience of hedonic search motives and consequently form more diverse consideration sets while purchasing a gift. Further, when working with a specific gift budget, high EBBT consumers are more likely to diversify their gift choices by buying a greater number of relatively lower‐priced gift items. We also find that the effects of the EBBT trait are significantly attenuated when the regulatory focus of the person making the gift decision is one of prevention rather than promotion. Discussion focuses on implications and future research directions regarding the relationship between exploratory buying behavior tendencies and consumer decision‐making.
Spondias mombin is culturally deprived in megafauna-free forest
Authors: Janzen Daniel H.
Published: July 2009

In the semi-deciduous forests of Santa Rosa National Park in the Pacific coastal lowlands of northwestern Costa Rica, the large and fast-growing tree Spondias mombin(Anacardiaceae) experiences greater than 95% post-dispersal seed predation by a bruchid beetle (Amblycerus spondiae) on its nuts that have been dispersed to any part of pristine or secondary successional forest. Nuts dispersed (by white-tailed deer) to abandoned pastures immediately adjacent to the forest suffer less than 20% post-dispersal seed predation but seedlings are killed by frequent grass fires. S. mombin displays significant recruitment of saplings and young trees only on forest edges free of fire for long intervals. The very high percent seed predation in the forest and the failure of many nuts to ever be dispersed away from the parent tree is attributed directly and indirectly to the absence of a herbivorous (frugivorous) megafauna that would have been part of the habitat of S. mombin through most of its evolutionary history. These large animals would have consumed large numbers of S. mombin fruits and thereby dispersed the nuts in such a manner as to have both led to more escape from bruchids and an overall reduction in the bruchid population density. By their defecation patterns, these mammals would also have defecated more nuts in sites of high quality for S. mombin sapling survival than is the case at present. In contemporary habitats, S. mombin is culturally deprived in that it can no longer interact with the habitats, animals and densities of animals whose selective pressures were a major force in the evolution of the tree's traits.
Altitudinal zonation of forest vegetation on Mount Kerinci, Sumatra: with comparisons to zonation in the temperate region of east Asia
Authors: Ohsawa M. , Nainggolan P. H. J. , Tanaka N. , Anwar C.
Published: July 2009

The altitudinal zonation of forests on Mount Kerinci, Sumatra (3800 m) is described and compared with that in the temperate region of east Asia. Nine plots were selected between 1750 m in altitude and the upper limit of vegetation at 3250 m, at intervals of about 200 m in altitude. The plots are distinguished according to their main dominants, and the population structure of the dominant species is examined. The lower forests have species showing the whole range of size classes as well as solitary giants as dominants, but the upper forests lack these giants and are floristically poorer. Between 1750 m (the start of well preserved natural vegetation) and 2950 m (the forest limit) three forest zones are distinguished, and between 2950 and 3250 m a scrub zone. Upper forest zones tend to be dominated by species of the same genus or family which form important understory components of the zone below. Based on floristic comparisons with mountains of higher latitudes (i.e. Himalayas and Japan), the two lower forest zones (up to 2400 m) represent a subtropical zone, and the upper forest zone a warm-temperate zone. Climatic conditions at the forest limit on Mount Kerinci are similar to those at the latitudinal limit of warm-temperate evergreen trees; in the Himalayas the forest limit represents the latitudinal limit of the cool-temperate, and in Japan of the subarctic Altitudinal zonation patterns change with latitude, reaching their most complex on subtropical mountains where the two floristic realms, the Boreal and Palaeotropical, meet. A scheme for the pattern of vegetation zonation in east Asia is proposed.
Nutrient dynamics of a Puerto Rican subtropical dry forest
Authors: Lugo Ariel E. , Murphy Peter G.
Published: July 2009

The distribution of the nutrients N, P and K in soil and vegetation and their mobility through litterfall and decomposition in mature and successional stands of a subtropical dry forest were studied in Guánica, Puerto Rico. Soils of the Guánica forest have high total amounts of N (9100 kg/ha), P (1820 kg/ha), and K (7460 kg/ha). However, high extractable Ca (>4000 mg/g) and pH (> 7–8) may explain why only 1.3 and 25% of the total P and K, respectively, were extractable. Total ecosystem storage of N, P and K was 10,300, 1900 and 7700 kg/ha, respectively, of which vegetation stored only 10, 2 and 3%, respectively. Litterfall returned 26, 18 and 180% per year of the N, P and K stored in the ground litter compartment. Trees retranslocated about 30 and 65% of the N and P required to satisfy aboveground net primary production and immobilized P in dead roots. Slow leaf decomposition (7.3 yr for 95% decomposition) released K faster than mass, P as fast as mass, and ash and N slower than mass. The use efficiency of P by litterfall was high compared with other tropical forests, while that of N and K was similar to other tropical and temperate forests. Cutting and regrowth of vegetation resulted in differences in the nutrient concentration in litterfall and nutrient use efficiency of successional vegetation.
Organization of a community of tadpoles in rain forest streams in Borneo
Authors: Inger Robert F. , Voris Harold K. , Frogner Karl J.
Published: July 2009

Samples of 29 distinct larval forms of anurans were collected in streams flowing through primary rain forest at Nanga Tekalit, Sarawak, at three periods spaced over 22 years. This assemblage of tadpoles lives in torrents, riffles, shingle areas, open pools, leaf drifts, protected side pools, potholes in rocky banks, bank seepages, and pools of small intermittent streams. Positive associations of species in types of microhabitats and co-occurrence within sites lead to recognition of four taxonomically heterogeneous groups: one concentrated in leaf drifts; one using riffles, shingle areas, and open pools; one concentrated in potholes; and one using side pools and potholes. Most pairs of larval forms having strong negative association are characterized by differences in morphology and feeding behaviour; they show little evidence of competitive relations. Between-sites variation in species composition differs among the types of microhabitats, leaf drifts showing the least amount of variation. Species composition within a site shows less change over intervals of 1–5 days than over intervals of 13–18 days. Variation in species composition is greater between sites than within sites over intervals of 9–31 days. Organization in this community seems to be effected by three factors: reproductive behaviour of adults and morphological and behavioural adaptations of tadpoles.
Root biomass of a mangrove forest in southern Thailand. 1. Estimation by the trench method and the zonal structure of root biomass
Authors: Komiyama Akira , Ogino Kazuhiko , Aksornkoae Sanit , Sabhasri Sanga
Published: July 2009

In a mangrove forest in southern Thailand, the root biomass was estimated for the Sonneratia zone, the Sonneratia-Bruguiera ecotone, the Bruguiera zone and the Rhizophora zone. A 0.2 m (width) × 15.5 m (length) × 1.0 m (depth) trench was dug between two trees of Rhizophora apiculata and the roots in the trench harvested, rinsed, sorted by diameter and weighed. The dry weight of roots collected from the trench was 135.6 kg, equivalent to a total root biomass of 437.5 t ha−1 including 220.5 t ha−1 of fine roots.

The root density distribution of a single tree was assumed to be predictable exponentially. Two variables of the equation were determined by iteration using the data from a trench excavation and tree distribution study. This equation was applied to 1.3 ha and the root biomass distribution was analysed. The root biomass in each of the above four zones was estimated at 171.8, 84.8, 242.6 and 509.5 t ha−1, respectively. The proportion of fine roots (<2 mm) ranged from 46.4% to 66.4%.
Carbon mineralization in semi-arid northeastern Australia: the role of termites
Authors: Holt John A.
Published: July 2009

The contribution of a population of mound building, detritivorous termites (Amitermes laurensis(Mjöberg)) to nett carbon mineralization in an Australian tropical semi-arid woodland has been examined. Carbon mineralization rates were estimated by measuring daily CO2flux from five termite mounds at monthly intervals for 12 months. Carbon flux from the mounds was found to be due to microbial activity as well as termite activity. It is conservatively estimated that the association ofA. laurensisand the microbial population present in their mounds is responsible for between 4%–10% of carbon mineralized in this ecosystem, and the contribution of all termites together (mound builders and subterranean) may account for up to 20% of carbon mineralized. Regression analysis showed that rates of carbon mineralization in termite mounds were significantly related to mound moisture and mound temperature. Soil moisture was the most important factor in soil carbon mineralization, with temperature and a moisture X temperature interaction term also exerting significant affects.
Recruitment, growth and mortality of tree species in a lowland dipterocarp forest in Peninsular Malaysia
Authors: Manokaran N. , Kochummen K. M.
Published: July 2009

Changes in the lowland dipterocarp forest structure and composition are described for a 34-year period between 1947 and 1981 in Sungei Menyala Forest Reserve, Peninsular Malaysia. Although tree density declined by about 10%, basal area changed little, averaging 32.4 m2 ha−1. Size class distributions in 1947 and 1981 were not significantly different. Mortality rates were independent of size class. Mortality exceeded recruitment during the first 16 years to 1963, but was thereafter almost exactly balanced by recruitment. Recruitment rate increased significantly for the latter part of the study.

Mortality was greater than average for understorey species and lower for emergents. Pioneer and late seral species together showed significantly higher mortality rates. Amongst the commoner species, emergent, late-seral and pioneer species showed the highest annual diameter growth rates with species averages over all size classes exceeding 3 mm yr−1; rates for main-canopy species were between 1.5 and 2.5 mm yr−1, and understorey species generally less than 2 mm yr−1.

Species richness was almost identical in 1947 and 1981 (243, 244 species), but a clear decline (to 229 species) between 1953 and 1971 was recovered by 1981. Most species showed little net change in density over the 34-year period, but eight of the 32 commoner species showed significant changes, all unidirectional. These changes in species composition are not negligible, but further analysis is needed to determine if, for example, they are related to disturbance of part of the plot in 1917.
Input of wind–dispersed seeds into light–gaps and forest sites in a Neotropical forest
Authors: Augspurger Carol K. , Franson Susan E.
Published: July 2009

A total of 52,467 wind-dispersed seeds from 14 tree and 32 liana species fell into 1720 seed traps in 43 paired light-gap and adjacent forest sites on Barro Colorado Island, Panama. Summed at the community level, many more wind-dispersed seeds were collected from light-gaps (61%) than from forest sites (39%). They accumulated from March through May, 1984 to a density of 328 m-2 in gaps and 207 m-2 in forest sites. In contrast, only 33% of the total of 2782 non-wind-dispersed seeds were collected in gaps. Due to the extreme heterogeneity of the seed rain, these differences between gap and forest sites were not statistically significant at the community-level. Gap sites received more wind-dispersed seeds than adjacent forest sites in only 20 of 43 locations and in 13 of 20 species, especially those with individuals of high fecundity near gap sites. Of the estimated 105 million wind-dispersed seeds contributing to the seed rain of the 50 ha study plot, only 4.1% were dispersed to the rare gap sites that enhance the establishment and growth of seedlings for many of these species.
The mosaic theory of forest regeneration and the determination of forest composition in Ghana
Authors: Swaine M. D. , Hall J. B.
Published: July 2009

Early studies comparing adult and juvenile tree populations in West Africa described a contrast in flonstic composition between the two age classes. These studies have been mis-represented in more recent literature, and confusion has arisen over their interpretation.

Similar comparisons are reported here for six forest sites in Ghana. At any one site, clear differences in composition were recognized between adult and juvenile samples, but in terms of the variation in flonstic composition over the whole of the forest zone, they are slight and forest types appear to ‘breed true’.

At one site, Kade, compositional differences between size classes are fully described for all canopy species on a 0.25 ha plot. There was an abrupt change in composition at about 30 cm gbh. At this site, mortality rates for trees >30 cm gbh were greater amongst species with a high proportion of juveniles in the population. At other sites, changes in composition were sometimes abrupt, occurring at various size classes, or were more gradual.

The populations of some species included a large number of juveniles at all sample sites, but the converse, where species always have low densities of juveniles, were not seen. The possible implications of these results for future canopy composition are discussed in relation to temporal equilibrium, or lack of it, in tropical forest composition.
Phenological studies of shrub and treelet species in tropical cloud forests of Costa Rica
Authors: Koptur Suzanne , Haber William A. , Frankie Gordon W. , Baker Herbert G.
Published: July 2009

(1) During 1978–1981, marked individuals of 107 species of treelets and shrubs in three forest types between 1300–1650 m elevation at Monteverde, Costa Rica, were monitored at monthly intervals for behaviour of leafing, flowering, and fruiting.

(2) Although there was not a pronounced seasonal pattern of leafing activity, more species produced new leaves in the dry season. Species that flush large quantities of new leaves do so more commonly in the drier months. Leaf loss was gradual and unobtrusive in species observed.

(3) Flowering activity was greatest in the late dry season and early wet season. Most species exhibited extended flowering; only 15% of the species were massively flowering. Massive flowerers showed less seasonality than extended flowerers.

(4) Of the species studied, the majority had relatively unspecialized flowers which were visited by a variety of insects; small bee-pollination was the next most common, followed by hummingbird, beetle, settling moth, sphingid, butterfly, large bee and fly pollination (the pollination system of 18 species was unknown). Hummingbird pollinated species showed little seasonality of flowering when compared with species exhibiting small moth, and beetle pollination syndromes, as well as those with unspecialized flowers.

(5) The vast majority of species studied have fleshy fruits (sarcochores). Fruiting activity was less markedly seasonal than flowering. Species with fruit are more numerous in the second half of the year (the wet season and early dry season). The second year of the study saw substantially fewer species in fruit than the first year; this is attributed to the greater than usual rainfall and inclement weather during the peak flowering season.

(6) Cloud forest shrub and treelet phenology is compared with patterns of other forests that have been studied. In general, the greater the rainfall, the less seasonality of flowering and fruiting is seen. Although Monteverde is very wet, rainfall is intermediate between that of lowland dry and lowland wet forest in Costa Rica. Seasonality of flowering and fruiting at Monteverde is more pronounced than at La Selva (wet) and less obvious than in Guanacaste (dry).
A re-assessment of effects of fire on miombo regeneration in the Zambian Copperbelt
Authors: Chidumayo E. N.
Published: July 2009

In 1933/34 eight coppice plots were established in Brachystegia-Julbemardia (miombo) woodland at Ndola in the Copperbelt area of Zambia by the Forestry Department. These plots have been maintained under fire protection, annual early or late dry season burning since 1934/35. Before establishment stems over 20.3 cm girth at breast height were enumerated. Three of the eight plots (one fire protected and two annually early burnt) were enumerated in 1982, 48–49 years after establishment. In addition, a coppice plot at Chitwi, 16 km southwest of the Ndola plots, cleared in 1972 and left to regenerate naturally was enumerated in May 1982 and August 1986 to assess woody plant growth.

The density of stems over 20.0 cm girth in the 13-year-old coppice at Chitwi was 2.5 times that in an adjacent shelterbelt woodland. The stem density in the fire protected plot at Ndola in 1982 was 86% of the pre-felling density while in one of the early burnt plots it was 95% of the pre-felling density. The protected plot had the lowest species diversity after 49 years, largely because of the loss of 11 understorey species that were present before felling.

There were no significant differences in stem mean girth at breast height (gbh) of canopy species in the Ndola plots under fire protection and early burning regimes. Mean annual gbh increments of abundant species were estimated at 1.17–2.21 cm yr−1 and 0.59–1.42 cm yr−1 during 0–9 and 0–49 year age-periods, respectively. Estimated mean annual basal area increments for stems over 30 cm gbh were 0.35 m2 ha−1 for the 13-year-old coppice and 0.24–0.27 m2 ha−1 for the 49-year-old coppice. These results indicate a decrease in both gbh and basal area increment with increasing age of miombo coppice
Canopy dynamics and light climates in a tropical moist deciduous forest in India
Authors: Lee David W.
Published: July 2009

The canopy dynamics and light climates within a 20 by 60 m quadrat were studied in a disturbed moist deciduous forest near Bombay, India. A map was drawn of individual trees within the quadrat, the taxa were identified, and their phenology was followed from November 1984 to July 1985. The quadrat contained 14 species, the most common being Tectona grandis, Terminalia tomentosa, Butea monosperma, Mitragyne parviflora and Albizia procera. Some individuals were in leaf at all times, more so at the moister east end of the quadrat. In November at the end of the rainy season, light measurements documented percentages of total daily photosynthetic photon fluence (PPF) at 10.0% of full sunlight; 44% of this flux was due to sun-flecks whose duration was approximately 17% of the daytime hours. Values for six sites were similar to mid-day measurements along a 40 m transect, and consistent with the 94% canopy cover of the sites, photographed with a fish-eye lens. The March dry season measurements revealed a more intense radiation environment (54% of solar PPF), and 59% of the photosynthetic photon flux density at mid-day along the transect. Canopy openings were increased to a mean of 59.4%. Light in the understorey in November was spectrally altered, with typical R:FR ratios of 0.30, compared to March values identical to those of sunlight, at 1.10.
Microhabitat variation in an African savanna: effects of woody cover and herbivores in Kenya
Authors: Georgiadis Nicholas J.
Published: July 2009

Effects of extreme livestock pressure on the abundance and distribution of a drought-deciduous shrubSericocomopsis pallida, and effects of the shrub canopy on microclimate, soil fertility and grass production, were studied in savanna grasslands of southern Kenya. Canopy volume declined with increasing herbivore pressure, but shrub density was not systematically affected, suggesting strong resilience against destruction by herbivores. However, shrubs became more aggregated with increasing herbivory, suggesting that clumps of individuals are more resilient to destruction than are isolated individuals. Grass production was three times greater under the canopy ofS. pallidathan in the open. Comparisons of physical-chemical properties among soils derived from four microsites revealed far higher nutrient levels in sub-canopy soil than in soil derived from open ground between canopies, and radically different properties compared to soil heavily enriched with livestock dung and urine. Higher nutrient levels beneath the canopy most likely resulted from Utter decomposition.

A pot experiment, designed to simulate shading and soil conditions in the field, showed that grass growth promotion was largely due to a substantial increase in soil fertility beneath the canopy ofS. pallida, comparable to grass productivity in soil enriched with livestock excreta. However, this increase in sub-canopy grass production did not significantly increase regional grass layer production.
Nutrient content of bulk precipitation in south-central Java, Indonesia
Authors: Bruijnzeel L. A.
Published: July 2009

The chemical composition of bulk precipitation was studied for a period totalling 18 months between 1975 and 1978 at a high rainfall site in central Java. The following elements were determined: calcium, magnesium, sodium, potassium, nitrate-nitrogen, chlorine, phosphate-phosphorus, silicon, aluminium, iron, manganese and pH. Ammoniacal nitrogen, total nitrogen and sulphate-sulphur were determined, during four weeks in May 1983. Concentrations of all elements rose dramatically during the exceptionally severe dry season of 1977 which may have caused accession rates for some nutrients to be overestimated (i.e. compared to a year with ‘normal’ rainfall) by about 10%. Results are explained in terms of prevailing wind directions and proximity to, or absence of, particular solute sources, such as the ocean, volcanoes or eroding lands.

Most elements exhibited intermediate concentrations when compared with data for other humid tropical locations; sodium and perhaps nitrogen were on the low side and pH on the high side of the spectrum. Annual accession rates at the study site were considerable by pan-tropical standards, mainly as a result of high rainfall totals. Comparing accession rates with 25-year-average nutrient immobilization rates in stemwood of local plantations ofPinus merkusiiJungh. et de Vr. andAgathis dammaraWarb. showed atmospheric inputs of magnesium and potassium to be high enough (theoretically) to account for losses of these elements in stemwood removal. Corresponding figures for nitrogen were 90% (Pinus) and 50% (Agathis), and for calcium and phosphorus 60 and 40% respectively (both species).
Tropical secondary forests
Authors: Brown Sandra , Lugo Ariel E.
Published: July 2009

The literature on tropical secondary forests, defined as those resulting from human disturbance (e.g. logged forests and forest fallows), is reviewed to address questions related to their extent, rates of formation, ecological characteristics, values and uses to humans, and potential for management. Secondary forests are extensive in the tropics, accounting for about 40% of the total forest area and their rates of formation are about 9 million ha yr−1. Geographical differences in the extent, rates of formation and types of forest being converted exist.

Secondary forests appear to accumulate woody plant species at a relatively rapid rate but the mechanisms involved are complex and no clear pattern emerged. Compared to mature forests, the structure of secondary forest vegetation is simple, although age, climate and soil type are modifying factors. Biomass accumulates rapidly in secondary forests, up to 100 t ha−1during the first 15 yr or so, but history of disturbance may modify this trend. Like biomass, high rates of litter production are established relatively quickly, up to 12–13 t ha−1yr−1by age 12–15 yr. And, in younger secondary forests (< 20 yr), litter production is a higher fraction of the net primary productivity than stemwood biomass production. More organic matter is pro duced and transferred to the soil in younger secondary forests than is stored in above-ground vegetation. The impact of this on soil organic matter is significant and explains why the recovery of organic matter in the soil under secondary forests is relatively fast (50 yr or so). Nutrients are accumulated rapidly in secondary vegetation, and are returned quickly by litterfall and decomposition for uptake by roots.

We propose a model of the gains and losses, yields and costs, and benefits and tradeoffs to people from the current land-use changes occurring in the tropics. When the conversion of forest lands to secondary forests and agriculture is too fast or land-use stages are skipped, society loses goods and services. To avoid such a loss, we advocate management of tropical forest lands within a landscape perspective, a possibility in the tropics because land tenures and development projects are often large.
Ecology of the Asian elephant in southern India. II. Feeding habits and crop raiding patterns
Authors: Sukumar R.
Published: July 2009

The Asian elephant's foraging strategy in its natural habitat and in cultivation was studied in southern India during 1981–83. Though elephants consumed at least 112 plant species in the study area, about 85% of their diet consisted of only 25 species from the order Malvales and the families Leguminosae, Palmae, Cyperaceae and Gramineae. Alteration between a predominantly browse diet during the dry season with a grass diet during the early wet season was related to the seasonally changing protein content of grasses.

Crop raiding, which was sporadic during the dry season, gradually increased with more area being cultivated with the onset of rains. Raiding frequency reached a peak during October-December, with some villages being raided almost every night, when finger millet (Eleusine coracana) was cultivated by most farmers. The monthly frequency of raiding was related to the seasonal movement of elephant herds and to the size of the enclave. Of their total annual food requirement, adult bull elephants derived an estimated 9.3% and family herds 1.7% in quantity from cultivated land. Cultivated cereal and millet crops provided significantly more protein, calcium and sodium than the wild grasses. Ultimately, crop raiding can be thought of as an extension of the elephant's optimal foraging strategy.
Flora and reproductive phenology of the rain forest at Bukit Timah, Singapore
Authors: Corlett Richard T.
Published: July 2009

The 71 ha Bukit Timah Nature Reserve contains the largest surviving area of primary rain forest in Singapore. The recorded vascular plant flora of the forest consists of at least 854 species: 787 angiosperms in 109 families, 65 pteridophytes and three gymnosperms. 58.6% of the species are trees or shrubs, 18.7% climbers, 12.3% terrestrial herbs, 8.8% epiphytes and hemi-epiphytes, 1.0% saprophytes and 0.6% parasites. The four families with most species -Rubiaceae, Euphorbiaceae, Orchidaceae and Moraceae - account for a quarter of the angio-sperm flora but contribute few large trees. Community reproductive phenology is charac-terized by supra-annual bursts of general flowering and fruiting, contrasting with a low back-ground level. After an exceptionally dry and sunny February, 1987, more than 150 species in 42 families flowered between late March and late May, followed by an equally well-defined fruiting peak 13 weeks later, between late June and late August.
Nitrogenase activity in soil and litter of a tropical lowland rain forest and an adjacent fernland in Sri Lanka
Authors: Maheswaran J. , Gunatilleke I. A. U. N.
Published: July 2009

Nitrogenase activity in the surface soil and litter layers from a tropical lowland rain forest and an adjacent fernland in Sri Lanka was measured by the acetylene reduction method. The total amount of acetylene reduced, a measure of biological nitrogen fixation, was greater in the fernland (38.4 µmol m−2 h−1) than in the forest (15.3–29.2 µmol m−2 h−1). In both ecosystems the nitrogenase activity was greater (59–85%) in the soil than in the litter layer. The rates of acetylene reduction in soil and litter showed an inverse relationship with the decay constants of mixed litter and a positive relationship was found between the rate of acetylene reduction and the C:extractable nitrogen ratio of the soil. The relatively greater rate of nitro genase activity coupled with the slower rate of litter decomposition in the fernland indicates that accumulation of nitrogen may result in the soil and litter layers of the deforested areas during their aggrading phases.
Termites, soil fertility and carbon cycling in dry tropical Africa: a hypothesis
Authors: Jones Julia Allen
Published: July 2009

Termites, particularly the mound building, fungus growing Macrotermitinae, reach densities of up to 400 termites m−2in soils of dry tropical Africa. The influence of Macrotermi tinae in increasing certain soil nutrients in mounds compared to adjacent soils has been documented, but the links between litter harvesting by termites, soil fertility, and global C cycling have not been explored. This study reviews the evidence from soil science, ecology and atmos pheric chemistry and generates hypotheses to explain the role of termites in dry tropical eco systems. It is suggested that termite activity exhaustively partitions litterfall among adjacent com peting colonies, where it is so thoroughly decomposed that little or no organic C is incorporated into the soils. Associated N, P, and cations build up in the mounds, but C apparently is emitted as CO2and CH4from the mounds. While not adequate to calculate nutrient fluxes through termites, the data available support the argument that termites contribute significantly to atmospheric fluxes of CO2and CH4. Moreover, they suggest a coupling of regional soil forming processes and the global C budget.
The influence of primary production on a raptor community in Hwange National Park, Zimbabwe
Authors: Hustler K. , Howells W. W.
Published: July 2009

We studied the breeding success and distribution of three species of eagles, four species of vultures and one species of eagle owl on two areas of differing primary productivity from 1973 to 1984. Densities of all species were lower in areas with lower productivity. Breed-ing success on both biomes was similar, the lower densities of birds on the least productive biome apparently compensating for the lower productivity. Eagles produced more one-egg clutches, laid later and reared fewer young in the period of poor rainfall, probably as a result of reduced productivity. Vulture data were difficult to interpret because abundant food at breed-ing time was created by ungulate population management throughout the entire study period. Concentrations of all species on the more productive biome, and solitary breeding on the least productive biome by a normally colonially breeding species, suggests that primary production also influences vulture densities and perhaps breeding success.
The biosystematics and evolution of thePolyalthia hypoleucaspecies complex (Annonaceae) of Malesia. II. Comparative distributional ecology
Authors: Rogstad Steven H.
Published: July 2009

One component of the high organismal diversity of tropical lowland rain forests is the existence of series of closely related, sympatric species. For example, the six distinct tree species of the monophyleticPolyalthia hypoleucacomplex regularly grow sympatrically in various combinations throughout the rain forests of Malesia. Theoretical and empirical evidence has been presented indicating that the members of such series either (1) are well differentiated with respect to at least one major niche component; or (2) may lack differentiated niches. In this study, certain sympatric members of the complex are shown to have clearly diverged in autecological characteristics that affect their distribution including: (1)P. glauca, P. hypoleuca, andP. sumatranadiffer in growth characteristics, height at maturity, seedling germination requirements, and are found on soils with differing degrees of hydration; (2)P. discolorgrows to a different height and on different substrate types than doesP. multinervis; and (3)P. glaucaandP. hypoleucaseedlings differ in transpiration characteristics and response to flooding and drought.