Wider Spectrum (wider + spectrum)

Distribution by Scientific Domains

Selected Abstracts

A general framework for neutral models of community dynamics

ECOLOGY LETTERS, Issue 12 2009
Omri Allouche
Abstract Neutral models of community dynamics are a powerful tool for ecological research, but their applications are currently limited to unrealistically simple types of dynamics and ignore much of the complexity that characterize natural ecosystems. Here, we present a new analytical framework for neutral models that unifies existing models of neutral communities and extends the applicability of existing models to a much wider spectrum of ecological phenomena. The new framework extends the concept of neutrality to fitness equivalence and in spite of its simplicity explains a wide spectrum of empirical patterns of species diversity including positive, negative and unimodal productivity,diversity relationships; gradual and highly delayed declines in species diversity with habitat loss; and positive and negative responses of species diversity to habitat heterogeneity. Surprisingly, the abundance distribution in all of these cases is given by the dispersal limited multinomial (DLM), the abundance distribution in Hubbell's zero-sum model, showing DLM's robustness and demonstrating that it cannot be used to infer the underlying community dynamics. These results support the hypothesis that ecological communities are regulated by a limited set of fundamental mechanisms much simpler than could be expected from their immense complexity. Ecology Letters (2009) 12: 1287,1297 [source]

Fungal biodiversity, pollen morphology and leaf surface of some native species in Egypt

S. I. I. Abdel-Hafez
Five native species of the flora of Egypt: Adonis dentata Delile, Ranunculaceae; Papaver dubium L., Papaveraceae; Matthiola longipetala (Vent.) DC., Brassicaceae; Malva parviflora L., Malvaceae; and Erodium laciniatum (Cav.) Willd., Geraniaceae have been investigated morphologically, palynologically and mycologically. The total counts of phyllosphere fungi fluctuated between 223 and 388 colonies/100 leaf segments giving maximum on Malva parviflora followed by Matthiola longipetala, Erodium laciniatum, Papaver dubium and Adonis dentata. The widest spectrum of genera (20) and species (39 and l variety) was recorded on Malva parviflora and the narrowest on Adonis dentata (9, 14). Sixty species and one variety belonging to 27 genera were collected from leaves (24 genera and 56 species and 1 variety) and anthers/pollen (16 genera and 27 species) of the five studied plants with the most frequently species were some members of Alternaria, Cladosporium, Fusarium and Mucor. Members of Aspergillus and Penicillium were prevalent only on leaves of Matthiola longipetala and Malva parviflora, while these members were infrequently recorded on leaf surfaces of Adonis dentata and Papaver dubium. Results revealed that density of hairs on the leaf surface and size of leaf blade, almost seem to be the most reliable factors of the biodiversity of the fungal spores on the studied taxa. On the other hand, reticulate or striate pollen surface had a wider spectrum of fungal biodiversity and higher densities of spores compared with echinate and scabrate surface. Pilz-Biodiversität, Pollen-Morphologie und die Blattoberfläche einiger einheimischer Arten in Ágypten Aus der Flora Ágyptens wurden die fünf einheimischen Arten Adonis dentata Delile, Ranunculaceae; Papaver dubium L., Papaveraceae; Matthiola longipetala (Vent.) DC., Brassicaceae; Malva parviflora L., Malvaceae; und Erodium laciniatum (Cav.) Willd., Geraniaceae morphologisch, palynologisch und mykologisch untersucht. Die Gesamtzahl an phyllosphären Pilzen schwankte zwischen 223 und 388 Kolonien/100 Blattsegementen. Das Maximum lag bei Malva parviflora, gefolgt von Matthiola longipetala, Erodium laciniatum, Papaver dubium und Adonis dentata. Das größte Spektrum an Gattungen (20) und Arten (39 und 1 Varietät) wurde bei Malva parviflora verzeichnet, das Minimum hingegen bei Adonis dentata (9, 14). An den fünf Arten wurden insgesamt 60 Arten und eine Varietät aus 27 Gattungen an Blättern (24 Gattungen, 56 Arten und eine Varietät) und Antheren/Pollen (16 Gattungen, 27 Arten) verzeichnet. Die häufigsten Arten gehörten zu den Gattungen Alternaria, Cladosporium, Fusarium und Mucor. Arten von Aspergillus und Penicillium wurden nur an Blättern von Matthiola longipetala und Malva parviflora nachgewiesen, während sie an den Blattoberflächen von Adonis dentata und Papaver dubium seltener waren. Aus den erzielten Resultaten ergibt sich, dass die Dichte des Haarbesatzes an der Blattoberfläche und die Größe der Blattspreite die entscheidenden Faktoren zur Biodiversität der Pilzsporen an den untersuchten Taxa sind. Anderseits kann man sagen, dass reticulate und striate Pollen im Vergleich zu einer echinaten und skabraten Oberfläche ein größeres Spektrum der Pilz-Biodiversität und eine höhere Sporendichte aufwiesen. [source]

Biological characteristics of breast cancer at the primary tumour and the involved lymph nodes

E. Dikicioglu
Summary Diminished oestrogen receptor (ER) expression in the involved axillary lymph nodes (ALN) in breast cancer compared with the primary tumour has been reported in previous studies. We have assessed a wider spectrum of tumour markers (ER, progesterone receptor (PgR), p53, Ki-67 and HER-2/neu) and compared extent and staining intensities at the primary tumour and the involved ALN on specimens of 22 cases with invasive ductal breast cancer. At the involved ALN, both the quantity of positive staining cells and the staining intensities for ER and PgR were decreased (p < 0.001 and p = 0.003, respectively). In contrast, the quantity of positive staining cells (p < 0.004) and the staining intensities for Ki-67 were increased. The differences for HER-2/neu and p53 staining at both sites were insignificant. The immunohistochemical staining properties of both the primary tumour and the ALN metastases showed no correlation with the number of involved ALN (p > 0.05). This study suggested that ALN metastasis might indicate a more unfavourable expression pattern of ER, PgR and Ki-67 in invasive ductal breast cancer. [source]

Changing concepts of bladder regeneration

Akihiro Kanematsu
Abstract: During the last decade, there has been a dramatic increase in studies aimed at regeneration of the urinary bladder. Many studies employed animal-derived or synthetic materials as grafts for experimental bladder augmentation models, with or without additional measures to promote regeneration, such as autologous cell transplantation or growth factor loading. However, in spite of encouraging results in several reports, few methodologies have shown proven definitive clinical utility. One major problem in these studies is the lack of a clear distinction between native and regenerated bladder in total bladder function after augmentation. Another crucial problem is the absorption and shrinkage of larger grafts, which may result from insufficient vascular supply and smooth muscle regeneration. In contrast, researchers have recently attempted to establish alternative regenerative strategies for treating bladder diseases, and have employed far more diverse approaches according to the various pathological conditions to be treated. For total replacement of the bladder after cystectomy for invasive bladder cancer, urothelium-covered neobladder with non-urinary tract backbone remains a viable choice. In addition, functional bladder diseases such as urinary incontinence, weak detrusor, or non-compliant fibrotic bladder have also been major targets for many leading research groups in this field. These conditions are studied much more from different therapeutic standpoints, aiming at the prevention or reversal of pathological conditions in muscle remodeling or neural control. Such altered research direction would inevitably lead to less surgically based basic biological research, and also would include a far wider spectrum of adult and pediatric bladder diseases, from overactive bladder to dysfunctional voiding. [source]

RELU Special Issue: Editorial Reflections

David R. Harvey
Abstract This special issue is special in two major dimensions: the papers range intentionally over a much wider spectrum of social and natural science approaches and disciplines than is normal for the Journal of Agricultural Economics; and, the articles relate to ongoing research rather than completed work. These reflections, perhaps peculiar to a practicing applied economist and policy analyst, concentrate on the lessons to be learned and messages to be heard from the RELU programme, both by those engaged on the programme's research portfolio, and by other researchers. [source]

Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa

I. Colin Prentice
Abstract BIOME 6000 is an international project to map vegetation globally at mid-Holocene (6000 14C yr bp) and last glacial maximum (LGM, 18,000 14C yr bp), with a view to evaluating coupled climate-biosphere model results. Primary palaeoecological data are assigned to biomes using an explicit algorithm based on plant functional types. This paper introduces the second Special Feature on BIOME 6000. Site-based global biome maps are shown with data from North America, Eurasia (except South and Southeast Asia) and Africa at both time periods. A map based on surface samples shows the method's skill in reconstructing present-day biomes. Cold and dry conditions at LGM favoured extensive tundra and steppe. These biomes intergraded in northern Eurasia. Northern hemisphere forest biomes were displaced southward. Boreal evergreen forests (taiga) and temperate deciduous forests were fragmented, while European and East Asian steppes were greatly extended. Tropical moist forests (i.e. tropical rain forest and tropical seasonal forest) in Africa were reduced. In south-western North America, desert and steppe were replaced by open conifer woodland, opposite to the general arid trend but consistent with modelled southward displacement of the jet stream. The Arctic forest limit was shifted slighly north at 6000 14C yr bp in some sectors, but not in all. Northern temperate forest zones were generally shifted greater distances north. Warmer winters as well as summers in several regions are required to explain these shifts. Temperate deciduous forests in Europe were greatly extended, into the Mediterranean region as well as to the north. Steppe encroached on forest biomes in interior North America, but not in central Asia. Enhanced monsoons extended forest biomes in China inland and Sahelian vegetation into the Sahara while the African tropical rain forest was also reduced, consistent with a modelled northward shift of the ITCZ and a more seasonal climate in the equatorial zone. Palaeobiome maps show the outcome of separate, independent migrations of plant taxa in response to climate change. The average composition of biomes at LGM was often markedly different from today. Refugia for the temperate deciduous and tropical rain forest biomes may have existed offshore at LGM, but their characteristic taxa also persisted as components of other biomes. Examples include temperate deciduous trees that survived in cool mixed forest in eastern Europe, and tropical evergreen trees that survived in tropical seasonal forest in Africa. The sequence of biome shifts during a glacial-interglacial cycle may help account for some disjunct distributions of plant taxa. For example, the now-arid Saharan mountains may have linked Mediterranean and African tropical montane floras during enhanced monsoon regimes. Major changes in physical land-surface conditions, shown by the palaeobiome data, have implications for the global climate. The data can be used directly to evaluate the output of coupled atmosphere-biosphere models. The data could also be objectively generalized to yield realistic gridded land-surface maps, for use in sensitivity experiments with atmospheric models. Recent analyses of vegetation-climate feedbacks have focused on the hypothesized positive feedback effects of climate-induced vegetation changes in the Sahara/Sahel region and the Arctic during the mid-Holocene. However, a far wider spectrum of interactions potentially exists and could be investigated, using these data, both for 6000 14C yr bp and for the LGM. [source]

Orbofiban: An orally active GPIIb/IIIa platelet receptor antagonist

Nancy S. Nicholson
Abstract A key role has been established for platelet activation and thrombus formation in the pathogenesis of acute coronary syndromes, and restenosis after percutaneous interventions. Antiplatelet agents that have a wider spectrum of activity than aspirin, and clopidogrel would be expected to provide improved antithrombotic protection. Preclinical studies were used to predict clinical efficacy of orally active GPIIb/IIIa antagonists such as xemilofiban, sibrafiban, lefradafiban, and orbofiban. While clinical trials have shown potent and sustained platelet inhibition, outcomes of trials with these first generation GPIIb/IIIa compounds have been disappointing. The active moiety of orbofiban is a potent and specific inhibitor of fibrinogen binding to GPIIb/IIIa, leading to inhibition of platelet aggregation to a wide variety of agonists. Studies comparing inhibition of aggregation and bleeding suggest that chronic inhibition of platelet aggregation can be achieved without major bleeding side effects. Thrombus formation is prevented in canine models of thrombosis. Orbofiban is approximately 28% bioavailable with a t1/2 of 18,hr. The high bioavailability, long half-life, and potential safety suggest orbofiban would be suitable for chronic oral administration. Clinical data demonstrate that orally administered orbofiban has the desired pharmacodynamic effect of inhibiting platelet aggregation but does not demonstrate clinical benefit when examined in large-scale trials. © 2001 John Wiley & Sons, Inc. Med Res Rev, 21, No. 3, 211,226, 2001 [source]

Biochemical findings in common inborn errors of metabolism,

Marzia Pasquali
Abstract The application of tandem mass spectrometry (MS/MS) to newborn screening has led to the detection of patients with a wider spectrum of inborn errors of metabolism. A definitive diagnosis can often be established early enough to start treatment before symptoms appear. Here, we review common biochemical findings in disorders caused by deficiency of 3-methylcrotonyl-CoA carboxylase, isobutyryl-CoA dehydrogenase, 2-methyl-3-hydroxybutyryl-CoA dehydrogenase, 3-ketothiolase, 2-methylbutyryl-CoA dehydrogenase, and medium chain acyl CoA dehydrogenase. The diagnosis of these disorders requires biochemical confirmation by measurement of plasma acylcarnitine profile, urine organic acids, and urine acylglycine profiles followed by measurement of enzyme activity or detection of causative mutations. Early treatment can improve the outcome of these disorders. © 2006 Wiley-Liss, Inc. [source]

Fukutin gene mutations cause dilated cardiomyopathy with minimal muscle weakness

Terumi Murakami MD
Objective The fukutin gene (FKTN) is the causative gene for Fukuyama-type congenital muscular dystrophy, characterized by rather homogeneous clinical features of severe muscle wasting and hypotonia from early infancy with mental retardation. In contrast with the severe dystrophic involvement of skeletal muscle, cardiac insufficiency is quite rare. Fukuyama-type congenital muscular dystrophy is one of the disorders associated with glycosylation defects of ,-dystroglycan, an indispensable molecule for intra-extra cell membrane linkage. Methods Protein and functional analyses of ,-dystroglycan and mutation screening of FKTN and other associated genes were performed. Results Surprisingly, we identified six patients in four families showing dilated cardiomyopathy with no or minimal limb girdle muscle involvement and normal intelligence, associated with a compound heterozygous FKTN mutation. One patient died by rapid progressive dilated cardiomyopathy at 12 years old, and the other patient received cardiac implantation at 18 years old. Skeletal muscles from the patients showed minimal dystrophic features but have altered glycosylation of ,-dystroglycan and reduced laminin binding ability. One cardiac muscle that underwent biopsy showed altered glycosylation of ,-dystroglycan similar to that observed in a Fukuyama-type congenital muscular dystrophy patient. Interpretation FKTN mutations could cause much wider spectrum of clinical features than previously perceived, including familial dilated cardiomyopathy and mildest limb girdle muscular dystrophy. Ann Neurol 2006 [source]

Synthesis and antibacterial properties of peptidyl derivatives and cyclopeptides structurally based upon the inhibitory centre of human cystatin C: Dissociation of antiproteolytic and antibacterial effects

APMIS, Issue 7-8 2000
FRANCISZEK Kasprzykowski
Cysteine protease-inhibiting proteins of the cystatin superfamily can inhibit the replication of certain viruses and bacteria. The inhibitory centre of human cystatin C, the most widely distributed human cystatin, comprises three peptide segments. The present work describes the synthesis and antibacterial activity of 27 new peptidyl derivatives or cyclopeptides based upon the aminoterminal segment Arg8 -Leu9 -Val10 -Gly11. Fourteen of the new compounds displayed antibacterial activity against from 1 up to 9 of 17 clinically important bacterial species tested. Antiproteolytic activity of a compound was usually not required for its antibacterial capacity. Peptidyl diazomethanes generally had a very narrow antibacterial spectrum, inhibiting only Streptococcus pyogenes, whereas cyclopeptides and peptidyl derivatives of the general structure X-Arg-Leu-NH-CH(iPr)-CH2 -NH-Y had a much wider spectrum. The most potent of these substances displayed approximately equal minimal inhibitory and bactericidal concentrations of about 20 ,g/ml for both Staphylococcus aureus and S. pyogenes and were devoid of antiproteolytic activity. Several of the new substances could protect mice against lethal intraperitoneal challenge with S. pyogenes. Though their target remains to be disclosed, the group of substances here reported might be promising for the development of antibacterial drugs and the discovery of novel principles of action. [source]

From Member of the Company to Registered Auditor: The Role of the External Auditor in Corporate Governance

C. Richard Baker
Corporate governance has often been defined in a narrow way as comprising ,the range of control mechanisms that protect and enhance the interests of shareholders of business enterprises' (Fama and Jensen 1983). In the corporate governance literature there has also been a general focus on the structure and functioning of boards of directors and the responsibilities of audit committees in relation to external auditing (Rosenstein and Wyatt 1990;Shleifer and Vishny 1997). This article looks at the evolution of the role of external auditing in corporate governance. The role of the external auditor has changed through time, and consequently it should not be assumed that the role of external auditing is fixed or that it cannot be changed to meet societal needs and expectations. This observation leads to the primary argument of our article, which is that the role of the external auditor in corporate governance ought to be expanded in order to enhance the effectiveness of corporate governance for the benefit of a wider spectrum of stakeholders and society generally. [source]

Revisiting Fayol: Anticipating Contemporary Management

Lee D. Parker
This study argues that in classifying Fayol as a founding father of the Classical Management School, we have to some extent misrepresented this still important management theorist. The received Fayol portrayed in contemporary texts invariably emerges as a caricature of a much more insightful, complex, visionary and rounded management thinker. This study re-examines Fayol's personal and career history, as well as the arguments presented in his original work, General and Industrial Management. It finds that he was a much more complex and multidimensional figure than his conventional stereotype today, and that his management theories embraced a wider spectrum of approaches and concepts than traditionally identified with the classical management school of thought. In marked contrast to his traditional portrayal, this study uncovers traces of ideas and concepts that anticipated aspects of the human relations movement, systems-based contingency theory, the movement towards greater employee involvement in decision-making and elements of knowledge management. [source]