Apparent Break Research Articles

The Diversity of Extremely Red Objects

We present the results from a sensitive multiwavelength analysis of the properties of extremely red objects (EROs). Our analysis employs deep RIzJHK photometry of an 85 × 85 region to select a sample of 68 EROs with (R-K) ≥ 5.3 and brighter than K = 20.5 (5 σ). We combine this photometric data set with an extremely deep 1.4 GHz radio map of the field obtained from the VLA. This map reaches a 1 σ limiting flux density of 3.5 μJy, making it the deepest 1.4 GHz map taken, and is sensitive enough to detect an active galaxy with L1.4 1023 W Hz-1 at z > 1. If powered by a starburst, this radio luminosity is equivalent to a star formation rate of 25 M☉ yr-1 for stars more massive than 5 M☉. We identify radio counterparts to 21 of the EROs in this field with radio fluxes above 12.6 μJy and resolve one-third of these with our 16 FWHM beam. The spectral energy distributions of the majority of these galaxies are consistent with those expected for dust-reddened starbursts at z ~ 1. At these redshifts the radio luminosities of these galaxies indicate a median far-infrared luminosity of this population of LFIR 1012 L☉, meaning that half of the radio-detected sample are ultraluminous infrared galaxies (ULIRGs). We conclude that 16% ± 5% of the ERO population brighter than K = 20.5 are luminous infrared galaxies (LIRGs) at z ~ 1. We also use photometric classification of the colors of the EROs to investigate the mix of dusty active and evolved passive systems in the remaining ERO population that is undetected in our radio map. Based on this we suggest that at least 30% and possibly up to ~60% of all EROs with (R-K) ≥ 5.3 and K ≤ 20.5 are dusty, star-forming systems at z 1. Our best estimate of the star formation density in this highly obscured and optically faint (R 26) population is *(0.1-100 M☉) = 0.11 ± 0.03 M☉ yr-1 Mpc-3, comparable to estimates of that in Hα-emitting galaxies at z ~ 1 and greater than the estimates from UV-selected samples at these epochs. This lends support to the claims of a strong increase in the contribution from obscured systems to the star formation density at high redshifts. Using the observed counts of the radio-detected ERO population, we model the apparent break in the K-band number counts of the whole ERO population at K ~ 19-20 and propose that the passive ERO class dominates the total population in a relatively narrow magnitude range around K 20, with dusty, active EROs making up the bulk of the population at fainter limits.

'ASK YOUR DOCTOR ABOUT...': DIRECT-TO-CONSUMER PRESCRIPTION DRUG ADVERTISING AND THE HIV/AIDS MEDICAL MARKETPLACE

This essay combines economic, historical and textual analysis to map the role of consumer-directed pharmaceutical advertising in the construction of the HIV/AIDS medical marketplace. In an apparent break from previous mainstream media representations that focused on HIV/AIDS as a ‘death sentence’, recent pharmaceutical advertising emphasizes the manageability of the syndrome by telling patients/consumers how they can live with HIV/AIDS. Historicizing the rise of direct-to-consumer drug advertising, the essay examines how this mode of consumerism might facilitate ‘political activism at the point of consumption’ (Nava, 1999).

Motion of an eruptive prominence in the solar corona

A model for the nonradial motion of an eruptive prominence in the solar corona is proposed. Such motions, which can sometimes be inaccessible to observation, result in an apparent break in the causal link between eruptive prominences and coronal mass ejections. The global magnetic field of the Sun governs coronal plasma motions. The complex structure of this field can form prominence trajectories that differ considerably from a simple vertical rise (i.e., radial motion). A solar filament is modeled as a current-carrying ring or twisted toroidal magnetic rope in equilibrium with the coronal magnetic field. The global field is described using two spherical harmonics. A catastrophic violation of the filament equilibrium followed by its rapid acceleration—eruption—is possible in this nonlinear system. The numerical solution of the equations of motion corresponds well to the eruption pattern observed on December 14, 1997.

Multi‐scale description of a Sahelian synoptic weather system representative of the West African monsoon

AbstractA reference case of a Sahelian weather system observed during the Hydrological Atmospheric Pilot Experiment, HAPEX‐SAHEL, in August 1992, is described from a seasonal viewpoint as well as from synoptic and convective system viewpoints. It is shown that the case‐study is representative of the climatology at all these scales and presents many interacting scales and physical processes. At intraseasonal scale, the monsoon onset is characterized by an abrupt shift of precipitation together with a latitudinal migration of the African easterly jet (AEJ) and convection. At the month and day scales, the convective activity occurs in an apparent zonal break of the tropical easterly jet. The month of August 1992 exhibits intense synoptic activity. The vorticity field is characterized by northerly (dry) and southerly (wet) components located at 850 hPa on each side of the AEJ. Their intraseasonal modulation on a period of 20 to 40 days leads to active and break phases of the synoptic activity. Around 21 August, the 700 hPa vorticity field features the propagation of a typical easterly wave with a westward propagation of a cyclonic circulation followed by an anticyclonic circulation. Convective activity occurs mainly ahead of the 700 hPa vorticity maximum with the formation of a squall line on Aïr mountains propagating south‐westward at 15 m s−1. The convective system propagates about twice as fast as the vortex core, in contrast with the convection in the European Centre for Medium‐Range Weather Forecasts re‐analysis which stays in phase with the vorticity. The squall line corresponds to the largest contributor to the systems passing in August 1992 over the HAPEX‐SAHEL region; its environmental conditions and its effects on the atmosphere including the surface parameters are presented. Copyright © 2002 Royal Meteorological Society

Unusual spectral energy distribution of a galaxy previously reported to be at redshift 6.68.

Observations of distant galaxies are important both for understanding how galaxies form and for probing the physical conditions of the Universe at early times. It is, however, very difficult to identify galaxies at redshifts z > 5, because they are so faint and have few spectral characteristics. We previously reported the probable identification of a galaxy at z = 6.68, based on one line and an apparent break in the spectrum just shortwards of that, which we interpreted as Lyman alpha emission and the Lyman alpha break, where photons with shorter wavelengths are absorbed by the intervening neutral hydrogen gas. Here we present optical photometry that shows moderate detections of light in the B- and V-band images, which are inconsistent with the expected absence of flux shortwards of the Lyman alpha break for alpha galaxy at z > 5, and inconsistent with the previous flux measurement. Moreover, the spectral energy distribution for this object cannot readily be fitted by any known galaxy spectral template at any redshift, so the redshift is undetermined.

The X-ray variability of the Seyfert 1 galaxy MCG-6-30-15 from longASCAandRXTEobservations

We present an analysis of the long Rossi X-ray Timing Explorer (RXTE) observation of the Seyfert 1 galaxy MCG–6-30-15, taken in 1997 July. We have previously used the data to place constraints for the first time on the iron abundance–reflection fraction relationship, and now expand the analysis to investigate in detail the spectral X-ray variability of the object. Our results show that the behaviour is complicated. We find clear evidence from colour ratios and direct spectral fitting that changes to the intrinsic photon index are taking place. In general, spectral hardening is evident during periods of diminished intensity, and in particular, a general trend for harder spectra is seen in the period following the hardest RXTE flare. Flux-correlated studies further show that the 3–10 keV photon index Γ3–10 steepens, while that in the 10–20 keV band, Γ10–20, flattens with flux. The largest changes come from the spectral index below 10 keV; however, changes in the intrinsic power-law slope (shown by changes in Γ3–10), and reflection (shown by changes in Γ10–20) both contribute in varying degrees to the overall spectral variability. We find that the iron-line flux FKα is consistent with being constant over large time intervals on the order of days (although tentative evidence exists which show that FKα changes on shorter time intervals of order ≲10 ks during time periods surrounding flare events), and has an equivalent width which anticorrelates with the continuum flux and reflection fraction. A possible interpretation for the iron-line flux constancy and the relative Compton reflection increase with flux from the flux-correlated data is an increasing ionization of the emitting disc surface, while spectral analysis of short time intervals surrounding flare events hints tentatively at observed spectral responses to the flare. We present a simple model for partial ionization where the bulk of the variability comes from within 6rg. Temporal analysis further provides evidence for possible time (≲1000 s) and phase (φ∼0.6 rad) lags. Finally, we report an apparent break in the power density spectrum (∼4–5×10−6 Hz) and a possible 33-hour period. Estimates for the mass of the black hole in MCG–6-30-15 are discussed in the context of spectral and temporal findings.

HAS MACROECONOMIC PERFORMANCE REGAINED ITS ANTIPOVERTY BITE?

From the mid‐1980s to the early 1990s, several important studies examined the statistical relationship between the U.S. official poverty rate and overall economic performance. Most of these studies focused on the apparent break in this relationship beginning in the late 1970s or early 1980s. In this article, we present the results of our study of the relationship between macroeconomic performance and the poverty rate, using annual time‐series data on macroeconomic variables, such as the unemployment rate and per‐capita GDP growth from 1959 through 1998. Like these earlier studies, we also find that economic performance had a smaller antipoverty effect during the 1970s and 1980s than it did in earlier years. However, our estimates suggest that the weakened economic growth‐poverty relationship may have been an aberration of this period and that the expected relationship of the 1960s has again been reestablished in the 1990s. This is true even after accounting for changes in earnings inequality over the entire period.

Apparent Breaks in Scaling in the Earthquake Cumulative Frequency-Magnitude Distribution: Fact or Artifact?

It has been suggested that the finite width of the seismogenic lithosphere can have a strong effect on the frequency-moment relation for large earthquakes. Theories have been proposed in which large earthquakes have either a shallower or a steeper power-law slope in the incremental frequency-moment distribution, at characteristic seismic moments corresponding to earthquakes that rupture the entire seismogenic depth. However, many authors have applied the predicted double-slope distribution, which requires five independent parameters, to cumulative frequency data, and used the location of the break of slope to make inferences on characteristic size effects in the earthquake source in different seismotectonic regions. Here we examine the problem in a forward modeling mode by adding a realistic degree of statistical scatter to ideal incremental frequency-moment distributions of various commonly used forms. Adopting a priori the assumption of a piecewise linear distribution, we find in each case apparently statistically distinct breaks of slope that are not present in the parent distribution. These breaks of slope are artifacts produced by a combination of (a) high-frequency noise introduced by the random statistical scatter, (b) the more gradual natural roll-over in the cumulative frequency data near the maximum seismic moment, and (c) a systematic increase in the apparent regression coefficient due to the natural smoothing effect of the use of cumulative-frequency data. Therefore, if there is no apparent break of slope in the incremental distribution, it is unwise to interpret the cumulative-frequency data uniquely in terms of a break in slope. Until such breaks of slope can be distinguished in incremental-frequency data, we conclude that alternative methods (inversion of fault length and width from individual source mechanisms/aftershock sequences etc.) should be preferred for the examination of finite-depth effects, and that simpler solutions to the frequency-moment problem should be adopted for seismic-hazard applications.

Strain-induced symmetry breakdown in HOLZ lines from L12 titanium tri-aluminides

Energy filtered CBED patterns of the Cr-stabilized L1(2) phase of a titanium tri-aluminide alloy reveal deficit higher order Laue zone (HOLZ) lines in the zeroth order diffraction disk, for which the expected 4-mm symmetry is significantly broken in the <001> projection. This apparent break of symmetry may be explained by the presence of lattice strains of order 10(-3). Effects of strain-induced lattice distortions on HOLZ line symmetries are calculated by an introduction of rhombohedral, tetragonal or monoclinic distortions to the cubic unit cell. It is shown how tensile and shear components of strain affect the overall HOLZ line symmetries in different ways.

New Manufacturing Strategies and Labour in Latin America

Latin American scholars have shown considerable interest in the spread of Japanese methods in the continent and their potential impact on labour. Evidence from case studies shows intensive use of techniques such as multitasking, team-working, statistical process control and cellular manufacture. In some cases, firms have invested heavily in education and training in order to make viable new production strategies, and there is some evidence of attempts to stabilize labour forces and establish better plant-level relations with workers. This apparent break with the practices of peripheral Fordism does not appear to be accompanied by improvements in company-union relations. Where unions are strong, management have attempted to undermine union power. Where unions are weak, managements have continued to deny the legitimacy and relevance of union represcntation. Companies seek the flexibility to rnake labour work harder as well as smarter, and they are introducing individualized assessment and incentive schemes ...

Molecular genetic characterization and comparative mapping of the human PCP4 gene.

The mouse Pcp4 gene is highly expressed in brain, primarily in cerebellar Purkinje cells. It maps to chromosome 16 (Chr 16), in a region of conserved synteny with human chromosome 21 (Chr 21). To further characterize PCP4 and its possible contribution to cerebellar hypoplasia in trisomy 21, or Down Syndrome (DS), we cloned and sequenced the full length human cDNA, isolated a YAC which carries the entire gene, determined the gene structure, and characterized its expression. The gene spans at least 55 kb and contains two introns, the placement of which is the same in mouse. Expression in the mouse brain during development was detected at embryonic day 10, and thereafter through development. The PCP4 YAC was placed on the human Chr 21 YAC contig by a link to a YAC carrying the markers D21S15 and D21S349. This placement distal to ETS2 was confirmed by mapping on a somatic cell hybrid panel of Chr 21 translocations. This position caused an apparent break in gene order with mouse Chr 16. However, mapping in the mouse was reassessed, and Pcp4 and a linked marker, D16Mit71, were both moved distal to Ets2, corresponding to the position of PCP4 on Chr 21.

Effects of solvent treatment on crystallization kinetics of poly(p‐phenylene sulfide)

AbstractIsothermal melt crystallization kinetics were investigated by differential scanning calorimetry (DSC) for virgin and α‐chloronaphthalene solvent‐treated poly(phenylene sulfide) (PPS) systems. The overall crystallization rates were found to be much faster for the solvent‐treated PPS than for the virgin neat PPS. Additionally, the Avrami crystallization plot for the solvent‐treated PPS samples appeared as two straight portions with an apparent discontinuity, but as a continuous straight line for the virgin PPS system. After the treatment of solvent dissolution and subsequent drying, the residual trace α‐chloronaphthalene, upon being quenched to the crystallization temperatures, initiated some localized solvent‐induced nuclei‐like crystals in PPS. It was the nuclei that enhanced secondary crystallization in treated PPS during the second stage, and the higher extents of secondary crystallization in the solvent‐treated PPS caused the apparent discontinuous break in the Avrami plots. The causes for the difference were explained and the mechanism of the sequential primary/secondary crystallization kinetics for the solvent‐treated PPS was satisfactorily described with a proposed series‐parallel crystallization model. ©1995 John Wiley &amp; Sons, Inc.

Study spots ways to cut chemical waste output

In an apparent break with the traditional command-and-control approach to pollution abatement, Pont and the Environmental Protection Agency last week released a jointly prepared study that suggests EPA and industry can do more to cut chemical wastes by cooperation than by confrontation. The 141-page report outlines process modifications and chemical handling improvements that reduce production of chemical wastes. Moreover, the report finds, these changes, yield significant cost savings through improved production efficiencies and lowered waste disposal costs. The improvements are applicable to a broad range of chemical industry operations. Pont undertook the study—the Du Pont Chambers Works Waste Minimization Project—under a 1991 consent decree with EPA. The decree also included a $1.8 million fine for pollution violations at the 1450-acre Chambers Works, Pont's largest production site, in Deepwater, N.J. Paul V. Tebo, Ponf s vice president for safety, health, and environment, says the $1 mi...

A revised palynological sub-division of the Namurian of Jingyuan, northwest China

Studies carried out during the last decade have permitted the establishment of palynological zonal schemes for the Namurian deposits in China. The palynological zones proposed in this paper are based on material from Jingyuan, northwest China, where the exposures are well-developed without any apparent break and miospores are abundant and well preserved allowing the recognition of successive Namurian miospore zones. Seven miospore assemblage zones, i.e. Zones TA, VR, SB, KM, BP, AS and TQ, equivalent to goniatite Zones E 1, E 2, H, R 2, R 2-G 1, lower G 2 and upper G 2, respectively, according to the ammonoids and conodonts associated with them, covering the age from Namurian A to early Westphalian A, have been described. Some correlations of zones recognized in Jingyuan and those of Western Europe are briefly discussed.

Systematics and biostratigraphy of halobiid bivalves from the Martin Bridge Formation (Upper Triassic), northeast Oregon

A diverseHalobiafauna with rare ammonoids and conodonts is described from the type Martin Bridge Formation (Upper Triassic) of northeast Oregon. The composite section of black shale, mudstone, bedded micrite, limestone conglomerate, and halobiid lumachelle spans the Carnian–Norian boundary without apparent sedimentologic break or pronounced biotic extinction. The occurrence ofHalobia radiata radiataGemmellaro,Halobia? cf.teltschenensis(Kittl),H. superba superbaMojsisovics, andH. superba ornatissimaSmith (nomen translatum) with the ammonoidsDiscotropitessp. andArietoceltites? sp. low in the section indicates a late Carnian age (Dilleri?, Welleri to Macrolobatus Zones). These fossils occur below beds containing early Norian (Kerri Zone)H. beyrichi(Mojsisovics) and middle Norian (Rutherfordi?, Columbianus Zone)H. haloricaMojsisovics. The described fauna increases the halobiid and ammonoid diversity previously known from the Martin Bridge Formation despite synonymy of species previously reported from the section.

Scaling regimes of composite rainfall time series

The scaling behaviour of rainfall is analysed both for a range of scales in time and for a given scale in intensity using the statistics of the Fourier transform and the cumulative probability distribution. The analyses are applied to sets of long time series of daily rainfall (26 (8) files of 45 (90) years at 13 European stations) and sets of 5-min totals (13 single station summer seasons) thus covering a wide scaling range. The results of both analyses are interpreted in terms of their asymptotically hyperbolic (i.e. power law) behaviour: The ensemble averaged power spectra exhibit distinct scaling regimes with their associated power law behaviour, P ( f ) ∼ f –b : a regime of climatic variability (> 3 years: b ∼ 0.7), a spectral plateau (3 years to 1 month: b – 0) of general circulation fluctuations, a transition regime (1 month to 3 days: a dropping power spectrum without scaling), and a range governed by frontal systems (< 3 days: b ∼ 0.5). The transition region is interpreted as being generated by both of its neighbouring regimes whose scaling can therefore be expanded into the transition regime. Finally an apparent break in scaling (at 2.4 h) can possibly be attributed to the instruments inability to measure frequent weak signals. The tail-end of the hyperbolic distribution (characterizing the intermittency regime) is not approached smoothly but shows a break from the rest of the distribution. Finally, an outlook to multifractal scaling is given. DOI: 10.1034/j.1600-0870.1993.t01-3-00004.x

Magnetochemistry of the tetrahaloferrate(III) ions. 6. Crystal structure and magnetic ordering in [(pyH) 3Cl][FeCl 4] 2

The crystal structure, magnetic susceptibilities and specific heat of the title compound were determined by X-ray diffraction, susceptometry between 1.2 and 20 K, and adiabatic calorimetry between 1.5 and 39 K, respectively. The material is found to be a canted antiferromagnet with a critical temperature of 2.212 K. A λ-feature in the heat capacity at that temperature and an apparent break in the susceptibility curves are indicative of the manifestation of long-range order. A large degree of short-range order is observed to persist above the critical temperature, however. The compound crystallizes in the orthorhombic space group Pbca ( Z=8, a=13.040(2), b=15.929(2), c=27.014(5) Å and V=5611.2 Å 3). Bond lengths average 2.184(5) and 2.185(2) Å for Fe(1)Cl and Fe(2)Cl, respectively, within the slightly distorted tetrahedra. Single crystal magnetic susceptibility measurements of the sample show behavior consistent with that of a three-dimensional Heisenberg antiferromagnet with a small ferromagnetic peak whose maximum is identified at 2.00(1) K. This behavior is indicative of sublattice canting. A fit of the data from high temperature series expansions for a Heisenberg S=5/2 simple cubic lattice gives | J|/ k B=0.084(1) K with g=2.00.

The Velocity of M1 in the 1980s: Evidence from a Multivariate Time Series Model

The velocity of M declined in the 1980s after an upward trend over the previous twenty years. This apparent break in the process generating velocity was an important consideration in the Federal Reserve's deemphasis of M as an intermediate target in 1982. Discussion of the behavior of velocity has focused upon whether the process generating velocity underwent a shift, perhaps due to the financial innovation and deregulation in the 1980s, or whether the behavior of velocity merely reflects the underlying variability in its determinants. Tatom [34], Darby et al. [7], Stone and Thornton [33], and Rasche [30] provide summaries of this debate. No consensus has emerged on whether the process generating the velocity of M 1 shifted after 1982. The aim of the present paper is to analyze the behavior of velocity before and after 1982. The approach taken here is quite different from the traditional method of analyzing velocity which relies upon single-equation estimates of velocity or money demand functions. A vector autoregressive (VAR) model that contains the income velocity of M1 and its key economic determinants (income, interest rates, inflation, and money growth variability) is estimated using quarterly data for the period 1961:1-1981:4. The adequacy of this model is evaluated by calculating variance decompositions. A Monte Carlo simulation technique similar to that described in Doan and Litterman [8] is used to compute standard errors for the variance decompositions. This allows a judgement as to the significance of the response of velocity to its economic determinants. The effects of these variables on velocity for the period 1982:1-1988:4, the period of velocity's unusual behavior, are estimated through computation of historical decompositions. Formal stability tests are also performed to determine if there was a change in the process generating velocity after 1982.

Distribution and relative abundance of greenland Halibut ( Reinhardtius hippoglossoides (Walbaum)) in the Canadian Northwest Atlantic from Davis Strait to the northern Grand Bank

The catches of Greenland halibut ( Reinhardtius hippoglossoides (Walbaum)) were distributed from Davis Strait to the northern slopes of the Newfoundland Grand Bank with no apparent break in the continuity of the distribution. They were most abundant along the slopes of the continental shelf and in the deep channels around the fishing banks. They were caught in depths less than 200 m to depths greater than 1000 m. However, the preferred depth ranges varied with both latitude and season. For the areas where bottom temperature data were presented, fish were caught in a range of 0.0–6.0°C with a preference for warmer water (5.1–6.0°C) in northern Labrador during summer compared with colder water (< 0.0°C) during autumn in southern Labrador. For all areas examined larger and older fish predominated in the deeper waters and also increased in abundance moving progressively from south to north. An examination of age compositions from the commercial fishery which exists mostly in the more southerly area (Div. 2J, 3K and 3L) shows that it exploits a few younger age groups (6–9-year-olds in particular) while older fish ( > 10 years old) are hardly exploited at all.

The Chitradurga greenstone succession in south India and evolution of the late Archaean basin

AbstractThe Chitradurga greenstone succession of south India comprises a thick pile (~ 10 km) of late Archaean volcanic flows and terrigenous clastic sediments, metamorphosed from greenschist to low-grade amphilobite facies. An older near-shore sedimentary sequence of cratonic affiliation and an off-shore bimodal volcanic sequence were deposited contemporaneously on a gneissic basement. The volcanics are metasomatically altered, and major, minor and trace element data fail to discriminate the metavolcanics in terms of modern plate settings. A younger turbidite sequence of coarser elastics covered the older deposits without any apparent tectonic or erosional break. All the rocks of the succession display evidence of similar deformation, prior to invasion by younger granites (~ 2.5 Ga)in a late syn-kinematic phase.This suggests that initially a simple flat-lying downwarp in a continental crust served as the passive receptacle of the platform-type sediments, and also witnessed volcanism along extensional faulting. This phase of the basin was not associated with any compressive deformation. Subsidence of the Chitradurga basin by the denser volcanics and uplift in the gneissic borderlands provided the infrastructure for subsequent development of the younger turbidite sequence covering the still virtually undeformed older deposits. A compressive orogeny, accompanied by granitic intrusion (~ 2.5Ga) in a late kinematic phase, ultimately deformed and uplifted the basin-fill during the declining phase of basinal activity.There is no evidence in the belt to suggest that the plate-tectonic (Wilson cycle) processes, pending a terminal orogeny, were operative during evaluation of the Chitradurga basin.