Home About us Contact
|
Home About us Contact | ||
|
|
||
Epoch
Selected AbstractsA NEW EPOCH OF INDIVIDUALIZATION?PUBLIC ADMINISTRATION, Issue 3 2007PERSONALIZATION' OF PUBLIC SECTOR SERVICES, PROBLEMS WITH THE The paper discusses the role of the concept of ,personalization' in New Labour policy on the reform of public sector services. The analysis points to the contradictory ways in which the concept has been used in both policy statements, in the work of various authors, and in the think tank Demos, which has been closely associated with the diffusion of the concept. The correlative uncertainties with respect to implementation are discussed and related to the use of ,epochal' forms of argument in the justification of this latest instalment of public sector reform in the United Kingdom. [source] Palaeomonsoon variability in the southern fringe of the Badain Jaran Desert, China, since 130 ka BPEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2006Quanzhou Gao Abstract Taking the Chagelebulu Stratigraphic Profile as a typical example, a comprehensive study has been conducted to elucidate the palaeoclimatic and geomorphic evolution patterns in the southern fringe of the Badain Jaran Desert, which were found to be complex and polycyclic in the past 130 ka. However, the fluctuating magnitude is not as remarkable as that in the eastern China sandy region. The shift in climate from interglacial to glacial and the uplift process of the Qinghai,Xizang Plateau are the two leading forces driving the evolution of the climate and desert landforms in this area. Seventeen cycles of cold, dry and warm, humid climatic stages were recognized in the Upper Pleistocene Series of the profile. The sharp uplift of the Qinghai,Xizang Plateau superimposed a cool and arid climatic trend in this area. As a result of the climatic changes, the desert in this area has undergone multiple stages of expansion and contraction since 130 ka bp. The middle Holocene Epoch and the early stage of the Late Pleistocene Period were the main periods when the sand dunes became stabilized, and the early and late phases of the Holocene Epoch and late phase of the Pleistocene Epoch were the main periods when the previously stabilized sand dunes became mobile. The late phase of the Pleistocene Epoch was the most mobile stage, when the aeolian sand activities formed the essential geomorphic pattern of the Badain Jaran Desert. Copyright © 2005 John Wiley & Sons, Ltd. [source] Bright Epoch: Women and Coeducation in the American West by Andrea G. Radke-MossHISTORY OF EDUCATION QUARTERLY, Issue 1 2010MARY CLINGERMAN YARAN No abstract is available for this article. [source] Transnational Competence in an Emergent EpochINTERNATIONAL STUDIES PERSPECTIVES, Issue 2 2002Peter H. Koehn The article elaborates a framework for understanding the relevance of transnational competence to the dynamics that mark the transformations of our time. Nongovernmental stakeholders interacting through dense civil-society networks that permeate domestic-foreign frontiers bear increasing responsibility for the course of events. Based on linked interests, interorganizational knowledge generation and aggregation, partnerships, and interpersonal/intercultural interactions, they are deeply involved in addressing the many challenges posed by an ever more interdependent world. Transnational competence lubricates transterritorial networks and projects. Here, the authors extend earlier work that posited a worldwide skill revolution both by developing explicit dimensions of transnational competence and by introducing a behavioral component. The new framework provides analytical groundwork for explaining why some people, groups, and networks are more effective than others in forging meaningful transnational solidarities, negotiating and benefiting from the intensifying experience of globalization, and waging successful transnational campaigns. The article also probes how the spread of transnational competence is being facilitated by global migration and transmigration trends. The final section explores the governance implications of expanding transnational competency for the emergent epoch. [source] Clinical Evaluation of a Pacemaker Algorithm That Adjusts the Pacing Rate During Sleep Using Activity VariancePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2000FIRAT DURU DURU, F., et al.: Clinical Evaluation of a Pacemaker Algorithm That Adjusts the Pacing Rate During Sleep Using Activity Variance. Even though rate responsive pacemakers are able to regulate pacing rates based on sensor activity, they are set with a minimum rate that is not adjusted to provide rate decreases during sleep. The aim of this study was to evaluate the performance of the "Sleep Rate" feature, as compared to patient diaries and a validated method that identifies sleep from wrist actigraphy. In 19 patients (15 men; age 69 ± 8 years) with Pacesetter Trilogy DR+ pacemakers, the base rate and the sleep rate were set to 80 and 50 ppm, respectively. When the patients returned 2 days later, data recorded by the pacemaker and wrist actigraph were analyzed to find the agreement in corresponding sleep/wake periods. In 17 (89%) patients, the pacemaker went into the sleep mode. The total sleep time derived from actigraphy significantly exceeded the time during which the pacemaker was in sleep mode (1156.8 ± 83.4 vs 307.3 ± 77.2 minutes). Frequent reversions out of the sleep mode limited the total sleep time derived from the pacemaker. Cumulative analysis of the pacemaker data showed that the maximum time in the sleep mode was 78 minutes, and exceeded 1 hour in six instances, 30 minutes in 32 instances, and 15 minutes in 83 instances. Epoch by epoch comparisons revealed a good agreement (93.6 ± 1.8%) during wakefulness between the corresponding actigraph and pacemaker epochs. However, only 24.6 ± 3.7% of the corresponding epochs during sleep were identical, and the overall agreement was 54.4 ± 3.7%. Except for one patient who reported palpitations, patients did not suffer from a pacemaker rate change. The Sleep Rate feature provides rate reduction during sleep, while assuring rapid frequency response during physical activity. However, the current algorithm does not allow long periods of slow pacing rate during continuous sleep, possibly due to its conservative design and the presence of movement arousals, which has to be improved in future generation algorithms. [source] Petit-Lac (western Lake Geneva) environment and climate history from deglaciation to the present: a synthesisBOREAS, Issue 4 2005STEPHANIE GIRARDCLOS During the past decade, the presentation of seismic and sedimentological data has allowed reconstruction of the environment and climate history of the Petit-Lac (western Lake Geneva). Methods such as high-resolution seismics, sediment core analysis (macroscopic description, grain-size analysis, mineralogy) and palynology have been used to infer the changes in the lake's environment from deglaciation to the present. However, no final synthesis has been attempted to link this information in the development of a comprehensive evolution model of the Petit-Lac and its surrounding region. The Petit-Lac deglaciation occurred in three phases during the Rhône glacier retreat: the Geneva stage and the Coppet and Nyon re-advances. In the Versoix area, rivers developed just after the retreat of the Rhone glacier from the Nyon stage. The Nyon fan delta started at the end of the Bølling, and its lobe fluctuated in size and orientation in six phases from the Lateglacial to the present. The action of bottom currents (i.e. erosion, non-deposition surfaces) arising at the beginning of the Holocene indicates that the frequency and direction of strong wind regimes varied greatly. Lacustrine mass failures occurred at different time intervals: two between deglaciation and the end of the Oldest Dryas, two between the Bølling and the Younger Dryas, and four during the Holocene. From the Oldest Dryas to the Contemporary Epoch, the vegetation changed from a steppe to a climate-influenced forest, and finally to a mostly human-controlled forest. [source] Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma,JOURNAL OF QUATERNARY SCIENCE, Issue 2 2010Philip L. Gibbard Abstract In June 2009, the Executive Committee of the International Union of Geological Sciences (IUGS) formally ratified a proposal by the International Commission on Stratigraphy to lower the base of the Quaternary System/Period to the Global Stratotype Section and Point (GSSP) of the Gelasian Stage/Age at Monte San Nicola, Sicily, Italy. The Gelasian until then had been the uppermost stage of the Pliocene Series/Epoch. The base of the Gelasian corresponds to Marine Isotope Stage 103, and has an astronomically tuned age of 2.58 Ma. A proposal that the base of the Pleistocene Series/Epoch be lowered to coincide with that of the Quaternary (the Gelasian GSSP) was also accepted by the IUGS Executive Committee. The GSSP at Vrica, Calabria, Italy, which had hitherto defined the basal boundary of both the Quaternary and the Pleistocene, remains available as the base of the Calabrian Stage/Age (now the second stage of the revised Pleistocene). In ratifying these proposals, the IUGS has acknowledged the distinctive qualities of the Quaternary by reaffirming it as a full system/period, correctly complied with the hierarchical requirements of the geological timescale by lowering the base of the Pleistocene to that of the Quaternary, and fully respected the historical and widespread current usage of both the terms ,Quaternary' and ,Pleistocene'. Copyright © 2009 John Wiley & Sons, Ltd. [source] Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records,JOURNAL OF QUATERNARY SCIENCE, Issue 1 2009Mike Walker Abstract The Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record across the Pleistocene,Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs of climatic warming at the end of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high degree of precision. This climatic event is most clearly reflected in an abrupt shift in deuterium excess values, accompanied by more gradual changes in ,18O, dust concentration, a range of chemical species, and annual layer thickness. A timescale based on multi-parameter annual layer counting provides an age of 11 700 calendar yr b2,k (before AD 2000) for the base of the Holocene, with a maximum counting error of 99,yr. A proposal that an archived core from this unique sequence should constitute the Global Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch (Quaternary System/Period) has been ratified by the International Union of Geological Sciences. Five auxiliary stratotypes for the Pleistocene,Holocene boundary have also been recognised. Copyright © 2008 John Wiley & Sons, Ltd. [source] Tangible Heritage: Production of Astrolabes on a Laser EngraverCOMPUTER GRAPHICS FORUM, Issue 8 2008G. Zotti I.3.5 [Computer Graphics]: Computational geometry and object modelling , geometric algorithms, languages and systems; I.3.8 [Computer Graphics]: Applications Abstract The astrolabe, an analog computing device, used to be the iconic instrument of astronomers during the Middle Ages. It allowed a multitude of operations of practical astronomy which were otherwise cumbersome to perform in an epoch when mathematics had apparently almost been forgotten. Usually made from wood or sheet metal, a few hundred instruments, mostly from brass, survived until today and are valuable museum showpieces. This paper explains a procedural modelling approach for the construction of the classical kinds of astrolabes, which allows a wide variety of applications from plain explanatory illustrations to three-dimensional (3D) models, and even the production of working physical astrolabes usable for public or classroom demonstrations. [source] Selling archaeology and anthropology: early medieval artefacts at the Expositions universelles and the Wiener Weltausstellung, 1867,1900EARLY MEDIEVAL EUROPE, Issue 1 2008Bonnie Effros The archaeological and anthropological exhibits included in the four Expositions universelles held in Paris between 1867 and 1900 and the Wiener Weltausstellung in the Austro-Hungarian capital in 1873, contributed to the commercialization of antiquarianism and granted international attention to the amateur practitioners of these emerging disciplines. Displays of archaeological artefacts and human remains from the migration period and the early Middle Ages, juxtaposed with more exotic ,primitive' art, permitted organizers to broaden the aesthetic sensibilities of fairgoers and promote the acquisition of native antiquities. Exhibiting private collections of early medieval objects likewise justified nineteenth-century concepts of French and ,pan-Germanic' identity by linking them to iconic artefacts and romanticizing the barbarity of this distant epoch. [source] HAROLD WILSON'S DEVALUATION: A SALUTARY LESSONECONOMIC AFFAIRS, Issue 3 2008G. R. Steele The 1967 sterling devaluation opened the final act of the Keynesian epoch. The assurance ,that the pound here in Britain, in your pocket or purse or in your bank' had not been devalued, rests upon a ,fixed price' assumption invoked by John Maynard Keynes for the 1930s. It carried the implication that a currency revaluation is the only price change that is relevant to international competitiveness. That is nonsense. Devaluation succeeds in readjusting international payments only if it reduces the value of the pound in our pocket, purse or bank. [source] Cut-off scores in MMSE: a moving target?EUROPEAN JOURNAL OF NEUROLOGY, Issue 5 2010J. Morgado Background:, Cognitive tests are known to be influenced by language, culture and education. In addition, there may be an impact of ,epoch' in cognition, because there is secular increase in scores of IQ tests in children. If we assume this is a long lasting process, then it should persist later in life. Methods:, To test this hypothesis, we compared the performance of two cohorts of individuals (,50 years of age), evaluated 20 years apart using the Mini-Mental State Examination (MMSE). Results:, Study population included 135 participants in 1988 and 411 in 2008. MMSE scores were higher in 2008 than in 1988 for literacy x age-matched subgroups, the difference being significant for participants with lower literacy. Score variance was explained by literacy (, = 0.479, t = 14.598, P = 0.00), epoch (, = 0.34, t = 10.33, P = 0.00) and age (, = ,0.142, t = ,4.184, P = 0.00). Conclusion:, The present results are in accordance with a lifelong secular improvement in cognitive performance. The operational cut-off values may change with time, which may have clinical impact in the diagnosis of disorders like mild cognitive impairment or dementia. [source] EXPANSION OF GOLF COURSES IN THE UNITED STATES,GEOGRAPHICAL REVIEW, Issue 1 2008DARRELL E. NAPTON ABSTRACT. Twenty-five million Americans play golf on the nation's 16,000 courses each year. These golf courses constitute a significant national landscape feature. Since 1878, when the game arrived in the United States, golf has filtered down the urban, economic, and social hierarchies to become accepted by and accessible to most Americans. During the ensuing thirteen decades the number, location, and layout of the nation's golf courses have responded to many of the same driving forces that impacted the nation, including decentralization, growth of the middle class, war, economic depression, suburbanization, and the increasing role of the federal government. Four epochs of golf-course growth and diffusion show the growing acceptance of the sport and depict where courses were most likely to be constructed as a result of the prevailing forces of each epoch. [source] High-resolution Lopingian (Late Permian) timescale of South ChinaGEOLOGICAL JOURNAL, Issue 2-3 2010Shu-Zhong Shen Abstract The Lopingian represents the last epoch of the Palaeozoic Era and is bracketed by two severe biotic mass extinctions associated with dramatic environmental changes. The Lopingian Epoch lasted about 7 millions years and was also bracketed by large volcanic eruptions with the Emeishan volcanics at the base and the Siberian traps at the top. Considerable data have accumulated recently and in this paper we attempt to summarize these findings in a high-resolution Lopingian (Late Permian) timescale that integrates currently available multiple biostratigraphic, isotope chemostratigraphic, geochronologic and magnetostratigraphic data. In South China at least 13 conodont zones, multiple polarity zones and large carbon isotope fluctuations in the Lopingian are recognized and provide the high-resolution calibration that is essential to study this Late Permian interval characterized by Earth's largest biotic extinction. We also present a global correlation chart for the marine Lopingian Series. Copyright © 2010 John Wiley & Sons, Ltd. [source] Recognition of southern Gondwanan palynomorphs at Gondwana's northern margin,and biostratigraphic correlation of Permian strata from SE Turkey and AustraliaGEOLOGICAL JOURNAL, Issue 2-3 2010Ellen Stolle Abstract This study focuses on the palynology of Guadalupian (Middle Permian) strata of SE Turkey, especially on late Wordian and earliest Capitanian deposits, which are dated by foraminifers and can be chronostratigraphically related to the geological timescale. Herein, palynological species, such as Altitriletes densus, Cymatiosphaera gondwanensis and Praecolpatites sinuosus, previously characteristic for Pakistan, Australia and Antarctica are recorded. Therefore, the Permian biozones of marine fauna and the palynology of SE Turkey and the rest of the Arabian area and Australia are compared and correlated. This long-distance, eastern Gondwana-wide biostratigraphical correlation, conducted for the first time in the Guadalupian epoch in this study, showed that Corisaccites alutas has a similar Last Occurrence Datum in SE Turkey and in Australia. The correlation also showed that in the late Wordian a number of species were present throughout eastern Gondwana, whereas the distribution of other certain species was influenced by provincialism. Hence, it may be concluded that certain species of parent plants probably co-occurred Gondwana-wide, while the distribution of others was dependant on climate. Copyright © 2010 John Wiley & Sons, Ltd. [source] Tectonic and environmental evolution of Quaternary intramontane basins in Southern Apennines (Italy): insights from palaeomagnetic and rock magnetic investigationsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2010M. Porreca SUMMARY Southern Apennines is characterized by active extensional tectonics with NE,SW stretching direction. The seismicity of the region is very well understood and continuously monitored. In contrast, the onset of extensional tectonics is chronologically poorly constrained. The aim of this study is that to give important constraints on the development of extensional regime and the onset of the continental deposition during Quaternary in Southern Apennines. We report the results of palaeomagnetic and rock magnetic analyses from four Quaternary small intramontane basins in the Picentini Mountains (Southern Apennines). The sedimentary sequences are located at different altitudes, from 600 to 1200 m a.s.l., and were deposited in fluvial-lacustrine environments. We sampled 29 sites in clays and lacustrine limestones from Tizzano, Piano del Gaudo and Acerno basins and in red palaeosoils and matrix-supported conglomerates from the Iumaiano basins. In the clay and limestones samples magnetite, titano-magnetite, hematite and iron-sulphide have been recognized as the main magnetic carriers, whereas magnetite and hematite characterize the Iumaiano conglomerates and red soils. Palaeomagnetic results have been integrated with published radiometric data in order to constrain the age of each sedimentary basins. Sites from the Iumaiano basin, which represents the substrate of the Tizzano and Piano del Gaudo basins, show a reverse polarity and therefore have been attributed to the lower Matuyama chron. In contrast, palaeomagnetic data from Tizzano basin show a transition from reversed to normal polarity along the exposed section, which has been interpreted as the Matuyama/Brunhes transition. Sites from Acerno and Piano del Gaudo basins show a normal polarity, which, according to radiometric and pollen data, have been correlated to the Brunhes epoch. On the base of such results we discuss the tectono-stratigraphic evolution of the basins and the role of extensional tectonics in this portion of the Southern Apennine during the Quaternary. [source] ILLUSIONS OF POWER AND EMPIRE,HISTORY AND THEORY, Issue 4 2005JAMES N. ROSENAU ABSTRACT Subsequent to the end of the Cold War, analysts groped for an understanding of the overall structures of world politics that marked the emergence of a new epoch. As a result, the concept of empire became a major preoccupation, with the economic and military power of the United States considered sufficient for regarding it as an empire. Due to the proliferation of new microelectronic technologies and for a variety of other specified reasons, however, the constraints inherent in the new epoch make it seem highly unlikely that the U.S. or any other country can ever achieve the status of an empire. In effect, the substantial shrinkage of time and distance in the current period has led to the replacement of the age of the nation-state that originated with the Treaty of Westphalia in 1648 with the age of the networked individual. It is an age that has developed on a global scale and that has brought an end to the history of empires. [source] Brief breath holding may confound functional magnetic resonance imaging studiesHUMAN BRAIN MAPPING, Issue 4 2005David F. Abbott Abstract We demonstrate that breath holding of short durations may confound functional magnetic resonance imaging (fMRI) studies. Some subjects may hold their breath for a short time during task performance, especially if the task is challenging. Breath holding may therefore need to be considered specifically when interpreting fMRI experiments. We studied the temporal and spatial characteristics of cerebral T2*-weighted signal during short periods of breath holding by seven individuals in a 3-tesla MR scanner. We demonstrate that breath-holds as short as 3 s can result in regions of significant cerebral activation. More interestingly, we show that focal activation remains present when the data is analysed in a number of different ways, including analyses that correct for motion and model the task epoch as if it were 10 times longer than the actual breath-hold length. These findings have potential relevance for many researchers carrying out fMRI studies. Hum. Brain Mapping 24:284,290, 2005. © 2005 Wiley-Liss, Inc. [source] The New Mega-Projects: Genesis and ImpactsINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 4 2008FERNANDO DIAZ ORUETA Abstract Critiques of urban renewal and large-scale developments were prominent in the period 1960,80. In particular, they emphasized the negative environmental and social consequences of these schemes and especially attacked them for displacing low-income and ethnically different populations. In the 1980s and 1990s, we saw a decline in such projects in many places, responding to popular protest and intellectual dissent, along with a new emphasis on preservation. More recently, however, we see the revival of mega-projects, often connected with tourism and sports development and incorporating the designs of world-famous architects. Frequently these are on landfill or abandoned industrial sites. The symposium for which this is an introduction shows the growing convergence of North American and European projects. This convergence is visible in their physical form, their financing, and in the role played by the state in a world marked by neoliberalism. At the same time, the new projects do display a greater environmental sensitivity and commitment to urbanity than the modernist schemes of an earlier epoch. Résumé Dans la période 1960,1980, les critiques sur les aménagements à grande échelle et les grandes rénovations urbaines étaient fréquentes. Elles soulignaient notamment les conséquences environnementales et sociales néfastes de ces programmes, en leur reprochant en particulier de déplacer les populations à faible revenu ou d'appartenance ethnique différente. Dans les années 1980 et 1990, ces projets se sont faits plus rares dans bien des endroits, répondant à la contestation populaire et au désaccord des intellectuels, parallèlement à une préoccupation nouvelle pour la préservation. Dernièrement, pourtant, les mégaprojets ont réapparu, souvent associés à un aménagement touristique ou sportif et intégrant des créations d'architectes de renommée mondiale. Ils se situent fréquemment sur le site d'anciennes décharges ou usines abandonnées. Le symposium dont ce texte sert d'introduction montre la convergence croissante des projets nord-américains et européens, convergence que l'on constate dans leur forme physique, leur financement et dans le rôle que joue l'État dans un monde empreint de néolibéralisme. En même temps, les nouveaux projets affichent une sensibilitéà l'environnement et un engagement vis-à-vis de l'urbanité plus marqués que les programmes modernistes antérieurs. [source] Transnational Competence in an Emergent EpochINTERNATIONAL STUDIES PERSPECTIVES, Issue 2 2002Peter H. Koehn The article elaborates a framework for understanding the relevance of transnational competence to the dynamics that mark the transformations of our time. Nongovernmental stakeholders interacting through dense civil-society networks that permeate domestic-foreign frontiers bear increasing responsibility for the course of events. Based on linked interests, interorganizational knowledge generation and aggregation, partnerships, and interpersonal/intercultural interactions, they are deeply involved in addressing the many challenges posed by an ever more interdependent world. Transnational competence lubricates transterritorial networks and projects. Here, the authors extend earlier work that posited a worldwide skill revolution both by developing explicit dimensions of transnational competence and by introducing a behavioral component. The new framework provides analytical groundwork for explaining why some people, groups, and networks are more effective than others in forging meaningful transnational solidarities, negotiating and benefiting from the intensifying experience of globalization, and waging successful transnational campaigns. The article also probes how the spread of transnational competence is being facilitated by global migration and transmigration trends. The final section explores the governance implications of expanding transnational competency for the emergent epoch. [source] ECONOS in the epoch of CARS renaissanceJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2007A. M. Zheltikov Abstract The fifth European Conference on Nonlinear Optical Spectroscopy (ECONOS), continuing a long-standing tradition of European CARS Workshops (ECWs), was held in Smolenice, Slovakia, in April 2006. This special issue includes 15 contributions from ECONOS authors, giving a flavor of the most interesting topics covered by ECONOS'2006. Copyright © 2007 John Wiley & Sons, Ltd. [source] Sleep electroencephalogram in children with a parental history of alcohol abuse/dependenceJOURNAL OF SLEEP RESEARCH, Issue 1p2 2010LEILA TAROKH Summary We examined the sleep electroencephalogram (EEG) in 9- and 10-year-old children with (PH+) and without (PH,) a parental history of alcohol abuse/dependence to determine whether sleep disturbances associated with alcohol precede the onset of alcohol use. Participants slept on a fixed sleep schedule that ensured at least a 10-h time in bed for 1 week before an adaptation and baseline night. Data were collected in a four-bed sleep research laboratory. Thirty healthy boys and girls aged 9 or 10 years were classified as either PH+ or PH, based on DSM-IV criteria applied to structured parental interviews. All-night polysomnography was performed, sleep data were scored visually in 30-s epochs, and EEG power spectra were calculated for each epoch. All-night EEG spectra were calculated for rapid eye movement (REM) and non-REM (NREM) sleep, and cycle-by-cycle spectra were calculated for NREM sleep. The two groups did not differ on any sleep stage variable. All-night analyses revealed normalized power in the delta band and spindle range were lower in PH+ children. Within NREM sleep cycles PH+ children exhibited less normalized power in the delta band and spindle range compared with PH, children. This effect occurred in the first four cycles and was most pronounced in the first sleep cycle of the night. We found no signs of sleep disruption in sleep stages for PH+ children. Sleep EEG spectral differences, however, suggest that certain circuits responsible for ,protecting' sleep may be impaired in PH+ children, which may lead to disrupted sleep later in life. [source] Labour-market Institutions and Macroeconomic ShocksLABOUR, Issue 2 2003Yu-Fu Chen The effect of shocks depends on the nature of these institutions and the effect of institutional change depends on the macroeconomic environment. It follows that a given set of institutions may be appropriate in one epoch and not in another. We derive a dynamic model of labour demand in which the effect of firing costs on labour demand depends on the macroeconomic environment: when the level of macroeconomic activity is expected to drop and/or the trend rate of productivity growth is small, a rise in firing costs affects mainly (and adversely) the hiring decision and not the layoff decision. This makes firing costs harmful to employment when it may appear most appropriate. In contrast, firing costs can raise employment during periods of high growth and positive shocks. Our hypothesis is supported by empirical results using OECD data. [source] Phylogeography of ninespine sticklebacks (Pungitius pungitius) in North America: glacial refugia and the origins of adaptive traitsMOLECULAR ECOLOGY, Issue 18 2010JACLYN T. ALDENHOVEN Abstract The current geographical distribution of the ninespine stickleback (Pungitius pungitius) was shaped in large part by the glaciation events of the Pleistocene epoch (2.6 Mya,10 Kya). Previous efforts to elucidate the phylogeographical history of the ninespine stickleback in North America have focused on a limited set of morphological traits, some of which are likely subject to widespread convergent evolution, thereby potentially obscuring relationships among populations. In this study, we used genetic information from both mitochondrial DNA (mtDNA) sequences and nuclear microsatellite markers to determine the phylogenetic relationships among ninespine stickleback populations. We found that ninespine sticklebacks in North America probably dispersed from at least three glacial refugia,the Mississippi, Bering, and Atlantic refugia,not two as previously thought. However, by applying a molecular clock to our mtDNA data, we found that these three groups diverged long before the most recent glacial period. Our new phylogeny serves as a critical framework for examining the evolution of derived traits in this species, including adaptive phenotypes that evolved multiple times in different lineages. In particular, we inferred that loss of the pelvic (hind fin) skeleton probably evolved independently in populations descended from each of the three putative North American refugia. [source] An unbiased pilot survey for Galactic water masersMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010J. L. Caswell ABSTRACT The Australia Telescope Compact Array has been used in a fast surveying mode to study the 22-GHz transition of water in two small sample regions of the southern Galactic plane. The observations allow an unbiased search for water masers, including any that may have no association with masers from other molecules (or indeed, no association with any other detectable celestial object). Positions with arcsecond accuracy were obtained from the original survey data for detected sources, and these were re-observed at an epoch more than two years later. Variability of the spectra between the epochs was considerable: our total of 32 masers comprises 24 detected at both epochs, two detected at only the first epoch and six detected at only the follow-up epoch. The success of our surveying mode shows it to be a practical strategy for the difficult task of extending unbiased water maser surveys to a large portion of the Galactic plane. Our results show quantitatively the effect of variability on the completeness of surveys conducted at a single epoch. Most of our maser detections are new discoveries. Only four had previously been detected (in searches towards interesting targets in the survey area). The high density of water masers from our unbiased survey supports earlier suggestions that they are the most populous maser species, and one of the most sensitive and reliable tracers of massive young stellar objects , newly forming massive young stars. The spectra of nine masers show high-velocity emission, and they show a striking preponderance of blueshifted high-velocity features. This is compatible with such blueshifts being a characteristic of populations dominated by masers at the earliest evolutionary stage of star formation, in some cases prior to the onset of methanol masers. Amongst the high-velocity emission sources there are two new examples where blueshifted high-velocity outflows dominate the total emission; these substantially increase the previously known meagre population of five such objects and suggest that they may be surprisingly abundant. [source] Hydrodynamical N -body simulations of coupled dark energy cosmologiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010Marco Baldi ABSTRACT If the accelerated expansion of the Universe at the present epoch is driven by a dark energy scalar field, there may well be a non-trivial coupling between the dark energy and the cold dark matter (CDM) fluid. Such interactions give rise to new features in cosmological structure growth, like an additional long-range attractive force between CDM particles, or variations of the dark matter particle mass with time. We have implemented these effects in the N -body code gadget-2 and present results of a series of high-resolution N -body simulations where the dark energy component is directly interacting with the CDM. As a consequence of the new physics, CDM and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of CDM haloes are less concentrated in coupled dark energy cosmologies compared with ,CDM, and that this feature does not depend on the initial conditions setup, but is a specific consequence of the extra physics induced by the coupling. Also, the baryon fraction in haloes in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the ,CDM model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios. [source] A QSO host galaxy and its Ly, emission at z= 6.43,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009Tomotsugu Goto ABSTRACT Host galaxies of highest redshift quasi-stellar objects (QSOs) are of interest; they provide us with a valuable opportunity to investigate physics relevant to the starburst,active galactic nuclei (AGN) connection at the earliest epoch of the Universe, with the most luminous black holes. Here, we report an optical detection of an extended structure around a QSO at z= 6.43 in deep z,- and zr -band images of the Subaru/Suprime-Cam. Our target is CFHQS J2329-0301 (z= 6.43), the highest redshift QSO currently known. We have carefully subtracted a point spread function (PSF) constructed using nearby stars from the images. After the PSF (QSO) subtraction, a structure in the z, band extends more than 4 arcsec on the sky (Re= 11 kpc), and, thus, is well resolved (16, detection). The PSF-subtracted zr -band structure is in a similar shape to that in the z, band, but less significant with a 3, detection. In the z, band, a radial profile of the QSO+host shows a clear excess over that of the averaged PSF in 0.8,3 arcsec radius. Since the z, band includes a Ly, emission at z= 6.43, we suggest the z, flux is a mixture of the host (continuum light) and its Ly, emission, whereas the zr -band flux is from the host. Through a SED modelling, we estimate 40 per cent of the PSF-subtracted z,-band light is from the host (continuum) and 60 per cent is from Ly, emission. The absolute magnitude of the host is M1450=,23.9 (cf. M1450=,26.4 for the QSO). A lower limit of the SFR(Ly,) is 1.6 M, yr,1 with stellar mass ranging from 6.2 × 108 to 1.1 × 1010 M, when 100 Myr of age is assumed. The detection shows that a luminous QSO is already harboured by a large, star-forming galaxy in the early Universe only after ,840 Myr after the big bang. The host may be a forming giant galaxy, co-evolving with a super-massive black hole. [source] Surprising evolution of the parsec-scale Faraday Rotation gradients in the jet of the BL Lac object B1803+784MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2009M. Mahmud ABSTRACT Several multifrequency polarization studies have shown the presence of systematic Faraday Rotation gradients across the parsec-scale jets of active galactic nuclei, taken to be due to the systematic variation of the line-of-sight component of a helical magnetic (B) field across the jet. Other studies have confirmed the presence and sense of these gradients in several sources, thus providing evidence that these gradients persist over time and over large distances from the core. However, we find surprising new evidence for a reversal in the direction of the Faraday Rotation gradient across the jet of B1803+784, for which multifrequency polarization observations are available at four epochs. At our three epochs and the epoch of Zavala & Taylor, we observe transverse rotation measure (RM) gradients across the jet, consistent with the presence of a helical magnetic field wrapped around the jet. However, we also observe a ,flip' in the direction of the gradient between 2000 June and 2002 August. Although the origins of this phenomenon are not entirely clear, possibly explanations include (i) the sense of rotation of the central supermassive black hole and accretion disc has remained the same, but the dominant magnetic pole facing the Earth has changed from north to south, (ii) a change in the direction of the azimuthal B field component as a result of torsional oscillations of the jet and (iii) a change in the relative contributions to the observed RMs of the ,inner' and ,outer' helical fields in a magnetic-tower model. Although we cannot entirely rule out the possibility that the observed changes in the RM distribution are associated instead with changes in the thermal-electron distribution in the vicinity of the jet, we argue that this explanation is unlikely. [source] Modification of the 21-cm power spectrum by X-rays during the epoch of reionizationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009L. Warszawski ABSTRACT We incorporate a contribution to reionization from X-rays within analytic and seminumerical simulations of the 21-cm signal arising from neutral hydrogen during the epoch of reionization. The relatively long X-ray mean free path (MFP) means that ionizations due to X-rays are not subject to the same density bias as UV ionizations, resulting in a substantive modification to the statistics of the 21-cm signal. We explore the impact that X-ray ionizations have on the power spectrum (PS) of 21-cm fluctuations by varying both the average X-ray MFP and the fractional contribution of X-rays to reionization. In general, prior to the epoch when the intergalactic medium (IGM) is dominated by ionized regions (H ii regions), X-ray-induced ionization enhances fluctuations on spatial scales smaller than the X-ray MFP, provided that X-ray heating does not strongly suppress galaxy formation. Conversely, at later times when H ii regions dominate, small-scale fluctuations in the 21-cm signal are suppressed by X-ray ionization. Our modelling also shows that the modification of the 21-cm signal due to the presence of X-rays is sensitive to the relative scales of the X-ray MFP and the characteristic size of H ii regions. We therefore find that X-rays imprint an epoch and scale-dependent signature on the 21-cm PS, whose prominence depends on fractional X-ray contribution. The degree of X-ray heating of the IGM also determines the extent to which these features can be discerned. We further show that the presence of X-rays smoothes out the shoulder-like signature of H ii regions in the 21-cm PS. For example, a 10 per cent contribution to reionization from X-rays translates to a 20,30 per cent modulation in the 21-cm PS across the scale of H ii regions. We show that the Murchison Widefield Array will have sufficient sensitivity to detect this modification of the PS, so long as the X-ray photon MFP falls within the range of scales over which the array is most sensitive (,0.1 Mpc,1). In cases in which this MFP takes a much smaller value, an array with larger collecting area would be required. As a result, an X-ray contribution to reionization has the potential to substantially complicate analysis of the 21-cm PS. On the other hand, a combination of precision measurements and modelling of the 21-cm PS promises to provide an avenue for investigating the role and contribution of X-rays during reionization. [source] The evolution of the galaxy red sequence in simulated clusters and groupsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008A. D. Romeo ABSTRACT N -body/hydrodynamical simulations of the formation and evolution of galaxy groups and clusters in a , cold dark matter (,CDM) cosmology are used in order to follow the building-up of the colour,magnitude relation in two clusters and in 12 groups. We have found that galaxies, starting from the more massive, move to the red sequence (RS) as they get aged over times and eventually set upon a ,dead sequence' (DS) once they have stopped their bulk star formation activity. Fainter galaxies keep having significant star formation out to very recent epochs and lie broader around the RS. Environment plays a role as galaxies in groups and cluster outskirts hold star formation activity longer than the central cluster regions. However, galaxies experiencing infall from the outskirts to the central parts keep star formation on until they settle on to the DS of the core galaxies. Merging contributes to mass assembly until z, 1, after which major events only involve the brightest cluster galaxies. The emerging scenario is that the evolution of the colour,magnitude properties of galaxies within the hierarchical framework is mainly driven by star formation activity during dark matter haloes assembly. Galaxies progressively quenching their star formation settle to a very sharp ,red and dead' sequence, which turns out to be universal, its slope and scatter being almost independent of the redshift (since at least z, 1.5) and environment. Differently from the DS, the operatively defined RS evolves more evidently with z, the epoch when it changes its slope being closely corresponding to that at which the passive galaxies population takes over the star-forming one: this goes from z, 1 in clusters down to 0.4 in normal groups. [source] | ||||||||||||||||||||||||||||