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Humanities and Social Sciences25%
Chemistry25%

Selected Abstracts

Inlaid Multi-Walled Carbon Nanotube Nanoelectrode Arrays for Electroanalysis

ELECTROANALYSIS, Issue 1 2005
Jun Li
Abstract The rapid development in nanomaterials and nanotechnologies has provided many new opportunities for electroanalysis. We review our recent results on the fabrication and electroanalytical applications of nanoelectrode arrays based on vertically aligned multi-walled carbon nanotubes (MWCNTs). A bottom-up approach is demonstrated, which is compatible with Si microfabrication processes. MWCNTs are encapsulated in SiO2 matrix leaving only the very end exposed to form inlaid nanoelectrode arrays. The electrical and electrochemical properties have been characterized, showing well-defined quasireversible nanoelectrode behavior. Ultrasensitive detection of small redox molecules in bulk solutions as well as immobilized at the MWCNT ends is demonstrated. A label-free affinity-based DNA sensor has shown extremely high sensitivity approaching that of fluorescence techniques. This platform can be integrated with microelectronics and microfluidics for fully automated microchips. [source]

Lopingian (Late Permian) high-resolution conodont biostratigraphy in Iran with comparison to South China zonation

GEOLOGICAL JOURNAL, Issue 2-3 2010
Shu-Zhong Shen
Abstract Lopingian (Late Permian) conodonts and stratigraphy in northwest and central Iran have become hotly debated issues recently. We here use a sample-population approach, to develop a high-resolution conodont biostratigraphic framework for the Lopingian of Iran based on a re-examination of collections studied by Sweet from the Kuh-e-Ali Bashi area, northwest Iran; samples from the Abadeh C section and a nearby Permian-Triassic boundary section in the Abadeh area; and on published data. Six Wuchiapingian conodont zones, the Clarkina dukouensis, C. asymmetrica, C. leveni, C. guangyuanensis, C. transcaucasica and C. orientalis zones, and eight Changhsingian conodont zones, the Clarkina wangi, C. subcarinata, C. changxingensis, C. bachmanni, C. nodosa, C. yini, C. abadehensis and C. hauschkei zones, are described and figured. Diagnoses of ontogenetic characteristics to population variations of all the zone-naming species are re-described based on a sample-population taxonomic concept. The high-resolution Lopingian conodont zonation in Iran is closely correlative with its counterpart in South China. However, slightly different evolutionary trends in Clarkina populations existed at the very end of the Changhsingian in Iran and South China. This reflects a geographical cline and/or facies dependence and endemism in Clarkina populations rather than stratigraphic incompleteness of sections in either Iran or South China. Copyright © 2010 John Wiley & Sons, Ltd. [source]

The consolidation wave in U.S. food retailing: A European perspective

AGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 4 2001
Neil Wrigley
This article assesses, from the perspective of a European academic, the intense wave of acquisition and merger driven consolidation that swept through the U.S. food retail industry during the late 1990s. It reviews the characteristics and causes of that consolidation wave, placing emphasis on the regulatory history of the industry, the consequences of its financial reengineering during the 1980s, and the link between Wal-Mart's entry into the industry and the consolidation wave. The article then assesses the extent to which a shift in regulatory policy and practice by the Federal Trade Commission at the very end of the decade may have altered the pattern and scale of consolidation in the industry. Finally, it considers the future landscape of U.S. food retail consolidation, debating the consequences for the consolidation process of the period of FTC regulatory tightening during 1999/2000 and the likely implications of a Bush administration appointee heading the FTC [EconLit Classifications: L810, L190, G340, L400]. © 2001 John Wiley & Sons, Inc. [source]

Constraining the age of Lateglacial and early Holocene pollen zones and tephra horizons in southern Sweden with Bayesian probability methods,

JOURNAL OF QUATERNARY SCIENCE, Issue 4 2006
B. Wohlfarth
Abstract The sediment sequence from Hässeldala port in southeastern Sweden provides a unique Lateglacial/early Holocene record that contains five different tephra layers. Three of these have been geochemically identified as the Borrobol Tephra, the Hässeldalen Tephra and the 10-ka Askja Tephra. Twenty-eight high-resolution 14C measurements have been obtained and three different age models based on Bayesian statistics are employed to provide age estimates for the five different tephra layers. The chrono- and pollen stratigraphic framework supports the stratigraphic position of the Borrobol Tephra as found in Sweden at the very end of the Older Dryas pollen zone and provides the first age estimates for the Askja and Hässeldalen tephras. Our results, however, highlight the limitations that arise in attempting to establish a robust, chronologically independent lacustrine sequence that can be correlated in great detail to ice core or marine records. Radiocarbon samples are prone to error and sedimentation rates in lake basins may vary considerably due to a number of factors. Any type of valid and ,realistic' age model, therefore, has to take these limitations into account and needs to include this information in its prior assumptions. As a result, the age ranges for the specific horizons at Hässeldala port are large and calendar year estimates differ according to the assumptions of the age-model. Not only do these results provide a cautionary note for over-dependence on one age-model for the derivation of age estimates for specific horizons, but they also demonstrate that precise correlations to other palaeoarchives to detect leads or lags is problematic. Given the uncertainties associated with establishing age,depth models for sedimentary sequences spanning the Lateglacial period, however, this exercise employing Bayesian probability methods represents the best possible approach and provides the most statistically significant age estimates for the pollen zone boundaries and tephra horizons. Copyright © 2006 John Wiley & Sons, Ltd. [source]

A degradation signal recognition in prokaryotes

JOURNAL OF SYNCHROTRON RADIATION, Issue 3 2008
Eun Young Park
The degradation of ssrA-tagged substrates in prokaryotes is conducted by a subset of ATP-dependent proteases, including ClpXP complex. More than 630 sequences of ssrA have been identified from 514 species, and are conserved in a wide range of prokaryotes. SspB protein markedly stimulates the degradation of these ssrA-tagged substrates by the ClpXP proteolytic machine. The dimeric SspB protein is composed of a compact ssrA-binding domain, which has a dimerization surface and a flexible C-terminal tail with a ClpX-binding motif at its very end. Since SspB is an adaptor protein for the ClpXP complex, designed mutagenesis, fluorescence spectroscopy, biochemistry and X-ray crystallography have been used to investigate the mechanism of delivery of ssrA-tagged proteins. In this paper the structural basis of ssrA-tag recognition by ClpX and SspB, as well as SspB-tail recognition by ZBD, is described. [source]

KILLER WHALE PREDATION ON SPERM WHALES: OBSERVATIONS AND IMPLICATIONS

MARINE MAMMAL SCIENCE, Issue 3 2001
Robert L. Pitman
Abstract In October 1997 we observed a herd of approximately 35 killer whales (Orcinus orca) attack a pod of nine sperm whales (Physeter macrocephalus) 130 km off the coast of central California. During the four hours we watched, adult female killer whales, including some with calves, attacked in waves of four to five animals in what was apparently a "wound and withdraw" strategy. Adult male killer whales stood by until the very end when one charged in and quickly killed a seriously wounded sperm whale that had been separated from the group. The sperm whales appeared largely helpless: their main defensive behavior was the formation of a rosette ("marguerite"-heads together, tails out). When the killer whales were successful in pulling an individual out of the rosette, one or two sperm whales exposed themselves to increased attack by leaving the rosette, flanking the isolated individual, and leading it back into the formation. Despite these efforts, one sperm whale was killed and eaten and the rest were seriously, perhaps mortally, wounded. We also present details of two other encounters between sperm whales and killer whales that we observed. Although sperm whales, because of various behavioral and morphological adaptations, were previously thought to be immune to predation, our observations clearly establish their vulnerability to killer whales. We suggest that killer whale predation has potentially been an important, and underrated, selective factor in the evolution of sperm whale ecology, influencing perhaps the development of their complex social behavior and at-sea distribution patterns. [source]

Clinical implications of sugammadex

ANAESTHESIA, Issue 2009
J. E. Caldwell
Summary Sugammadex is a cyclodextrin molecule that encapsulates and inactivates rocuronium and vecuronium. As a result, any degree of neuromuscular block produced by rocuronium or vecuronium can be rapidly and completely reversed without autonomic effects. Because sugammadex is optimised for reversing rocuronium it is most likely to be used in conjunction with this drug. Sugammadex will allow deep levels of block to be maintained until the very end of surgery, and will allow block to be reversed at any time after rocuronium administration, even just a few minutes. The recommended dose-range is 2,16 mg.kg-1 (ascender), depending on the level of block. The availability of sugammadex reversal may increase the use of rocuronium, and decrease the use of suxamethonium and benzylisoquinoline neuromuscular blocking drugs. In addition, it will certainly increase pharmacy costs, which may be offset by faster recovery and discharge from the post-anesthesia recovery unit. Sugammadex may also change monitoring practices in that post-tetanic count will be required to quantify deep block, and quantitative monitoring of recovery may be driven by cost concerns in order to allow the use of the smallest dose of sugammadex that gives a satisfactory train-of-four ratio. Alternatively, monitoring may essentially be abandoned since a large dose of sugammadex will reliably reverse any degree of rocuronium-induced block. The ultimate clinical utility of sugammadex will be clear only after large-scale clinical use. [source]

Towards the earliest history of Kinda

ARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 1 2009
M.D. Bukharin
In the second century AD Rome could not protect the caravan trade in north-west Arabia to the south of Dedan with its own military detachments, stationed in Mad,'in and al-'Ul,. Rome seems to have attracted Aksum for the subjugation of the Arab nomads of north-west Arabia and protection of the ,Incense Road'. At the end of the second century AD Rome, Aksum and Saba' shared common interests: Aksum helped Rome to restore peace on the caravan routes, in which Saba' seemed to have been interested as well, and Rome provided a market for East African and South Arabian products. During the west Arabian campaign, described in the inscription RIÉ 277 (Monumentum Adulitanum II), which is to be dated to the very end of the second century AD, the unnamed Aksumite king, presumably Gad,rat, conquered the lands of Kinaidokolpites and Arrabites. The former name represents a combination of two names, the first of which seems to be derived from the name of Kinda (identification of the entire name with Kinda is taken for ,somewhat unlikely' in Retsö 2003: 450, n. 60). The Kinda seem to have been also known in the earlier classical tradition under the name of Kanraitai , the inhabitants of Ghamr dh,-Kinda , and thus were the most aggressive and dangerous obstacle for the Roman traders on the land routes in north-west Arabia and in the northern Red Sea in the first,second century AD. The Aksumite invasion forced the resettlement of the Kinda on the other branch of the ,Incense road', through modern Qaryat al-F,w , and its blockade, consequently followed at the beginning of the third century by the campaigns of the Sabaean king ,,'ir ,Awtar against them. [source]