bluuebunny/crossref_metadata_2025 huggingface dataset:
Under-reporting of notifiable infectious disease hospitalizations in a health board region in Ireland: room for improvement?
Authors: BRABAZON E. D. , O'FARRELL A. , MURRAY C. A. , CARTON M. W. , FINNEGAN P.
Published: March 2007

Rapid notification of infectious diseases is essential for prompt public health action and for monitoring of these diseases in the Irish population at both a local and national level. Anecdotal evidence suggests, however, that the occurrence of notifiable infectious diseases is seriously underestimated. This study aims to assess the level of hospitalization for notifiable infectious diseases for a 6-year period in one health board region in Ireland and to assess whether or not there was any under-reporting during this period. All hospital in-patient admissions from 1997 to 2002 inclusive with a principal diagnosis relating to ‘infectious and parasitic diseases’ (ICD codes 001–139) of residents from a health board region in Ireland were extracted from the Hospital In-Patient Enquiry System (HIPE). All notifiable infectious diseases were identified based on the 1981 Irish Infectious Disease Regulations and the data were analysed in the statistical package, JMP. These data were compared with the corresponding notification data. Analysis of the hospital in-patient admission data revealed a substantial burden associated with notifiable infectious diseases in this health board region: there were 2758 hospitalizations by 2454 residents, 17 034 bed days and 33 deaths. The statutory notification data comprises both general practitioner and hospital clinician reports of infectious disease. Therefore, only in cases where there are more hospitalizations than notifications can under-reporting be demonstrated. This occurred in nine out of 22 notifiable diseases and amounted to an additional 18% of notifications (or 572 cases) which were ‘missed’ due to hospital clinician under-reporting. The majority of these under-reported cases were for viral meningitis (45%), infectious mononucleosis (27%), viral hepatitis C unspecified (15%) and acute encephalitis (5·8%). This study has highlighted the extent of under-reporting of hospitalized notifiable infectious diseases, in a health board region in Ireland, which is a cause for concern from a surveillance point of view. If this under-reporting is similar in other health boards, then it would appear that the epidemiology of some notifiable diseases is incomplete both regionally and nationally. This under-reporting negatively impacts on the effectiveness of the notification process as a ‘real-time’ surveillance tool and an early warning system for outbreaks.
Linking syndromic surveillance with virological self-sampling
Authors: COOPER D. L. , SMITH G. E. , CHINEMANA F. , JOSEPH C. , LOVERIDGE P. , SEBASTIONPILLAI P. , GERARD E. , ZAMBON M.
Published: March 2007

Calls to a UK national telephone health helpline (NHS Direct) have been used for syndromic surveillance, aiming to provide early warning of rises in community morbidity. We investigated whether self-sampling by NHS Direct callers could provide viable samples for influenza culture. We recruited 294 NHS Direct callers and sent them self-sampling kits. Callers were asked to take a swab from each nostril and post them to the laboratory. Forty-two per cent of the samples were returned, 16·2% were positive on PCR for influenza (16 influenza A(H3N2), three influenza A (H1N1), four influenza B) and eight for RSV (5·6%). The mean time between the NHS Direct call and laboratory analysis was 7·4 days. These samples provided amongst the earliest influenza reports of the season, detected multiple influenza strains, and augmented a national syndromic surveillance system. Self-sampling is a feasible method of enhancing community-based surveillance programmes for detection of influenza.
The prehistory of panspermia: astrophysical or metaphysical?
Authors: Temple Robert
Published: March 2007

The panspermia theory has antecedents which go back to the Old Kingdom in Egypt, and which are also found in early Hinduism, the philosophy of the Greek pre-Socratic philosopher Anaxagoras, and amongst the Jewish and Christian Gnostics. It is remarkable how explicit some of these early sources are in suggesting that the entire cosmos is full of seeds, and that life on earth originated from them. Here, a survey is undertaken of all these early beliefs, in order to present a pre-history to these conceptions and show that such ideas appear to be as old as civilization itself.
Stochastic space‐time regional rainfall modeling adapted to historical rain gauge data
Authors: Zhang Zepu , Switzer Paul
Published: March 2007

Stochastic rainfall models are important tools both for practical issues and in studies of weather‐ and climate‐sensitive systems. We propose an event‐based model, continuous in space (two‐dimensional) and time, that describes regional‐scale, ground‐observed storms by a Boolean random field of rain patches. The model creates complex space‐time structures with a mathematically tractable framework. The estimation method relates temporal observations at fixed sites to the movement of the model storm rain field, thereby making historical rain gauge data suitable for model fitting. The model is estimated using hourly historical data at eight rain gauges in Alabama and tested for its capabilities in capturing statistical characteristics of the historical data, including rainfall intensity, rainfall intensity extremes, temporal correlation, effects of temporal aggregation, spatial coverage, and spatial correlation.
Evolution of convection during tropical cyclogenesis
Authors: Raymond David J. , Sessions Sharon L.
Published: March 2007

Central to tropical cyclogenesis is the changing behavior of moist convection as the cyclone evolves. Based on a cumulus ensemble model run in weak temperature gradient mode, we suggest that the mid‐level vortex created by early‐stage convection stabilizes the environment in way that favors further development. In particular, modeled convection occurring in the more stable environment produces heavy rainfall and concentrated inflow at low levels. Such inflow is needed for the development of the low‐level vortex characteristic of warm‐core tropical cyclones. The increase in humidity which is typical of developing cyclones also increases convective rainfall, but it does not act to concentrate the inflow at low levels.
Ice‐associated phytoplankton blooms in the southeastern Bering Sea
Authors: Jin Meibing , Deal Clara , Wang Jia , Alexander Vera , Gradinger Rolf , Saitoh Sei‐ichi , Iida Takahiro , Wan Zhenwen , Stabeno Phyllis
Published: March 2007

Ice‐associated phytoplankton blooms in the southeastern Bering Sea can critically impact the food web structure, from lower tropic level production to marine fisheries. By coupling pelagic and sea ice algal components, our 1‐D ecosystem model successfully reproduced the observed ice‐associated blooms in 1997 and 1999 at the NOAA/PMEL mooring M2. The model results suggest that the ice‐associated blooms were seeded by sea ice algae released from melting sea ice. For an ice‐associated bloom to grow and reach the typical magnitude of phytoplankton bloom in the region, ice melting‐resulted low‐salinity stratification must not be followed by a strong mixing event that would destroy the stratification. The ice‐associated blooms had little impacts on the annual primary production, but had significant impacts in terms of shifting phytoplankton species, and the timing and magnitude of the bloom. These changes, superimposed on a gradual ecosystem shift attributed to global warming, can dramatically alter the Bering Sea ecosystem.
Thermal anomaly near the Aigio fault, Gulf of Corinth, Greece, maybe due to convection below the fault
Authors: Doan M. L. , Cornet F. H.
Published: March 2007

A thermal profile has been measured in a 1000 m deep borehole intersecting the active Aigio fault, Corinth Rift, Greece. The heat flow is 53 mW/m2, indicating that the rifting process has no effect in heat flow. The temperature near the fault is higher than expected from a pure conductive model. This discrepancy is not due to fluid flow above the fault as shown by the long term monitoring of downhole pressure. Neither can it be attributed to the fault slip since the Aigio fault is a minor normal fault of the rift, with no very recent earthquake. We propose that the anomaly is due to the convection within the karst that constitutes the footwall. Numerical simulations give a correct estimate for the recorded temperature increase. This is an extreme case of thermal disturbance induced near a fault by local fluid circulation. The occurrence of convection outside geothermal area is very rare.
Electron periodicities in Saturn's outer magnetosphere
Authors: Carbary J. F. , Mitchell D. G. , Krimigis S. M. , Krupp N.
Published: March 2007

The Magnetospheric Imaging Instrument/Low‐Energy Magnetospheric Measurements Sensor (MIMI/LEMMS) instrument on the Cassini spacecraft has measured energetic electrons in the energy range 20–300 keV within Saturn's magnetosphere. In the outer magnetosphere, beyond ∼20 RS, these electrons and their spectral index display strong variations with periods comparable to the 10.76 hour (10 hours, 45 min, 36 s) period measured by radio observations of Cassini. Inside ∼20 RS, such electron variations may be present but are masked by satellite and ring effects. Electron periodicities are most easily recognized on the “nightside” segments of the Cassini orbits, although they are also observed to some extent on the dayside. For both dayside and nightside a wavelet analysis of detrended count rates in the 20–40 RS region reveals a mean period of 10.52 ± 0.74 hours (10 hours, 31 min ± 44 min) for the six electron channels investigated. If constrained to the nightside only, a wavelet analysis gives a mean period of 10.88 ± 0.52 hours (10 hours, 53 min ± 31 min). Covering five orbits of the Cassini spacecraft during the 2‐year period from Saturn Orbit Insertion (July 2004 to July 2006), this analysis indicates that a day‐night asymmetry exists in the electron periodicity in Saturn's outer magnetosphere and suggests that dayside periodicities are much less prominent than nightside or dawnside periodicities.
Paleomagnetism of Cretaceous rocks in the Jiaodong Peninsula, eastern China: Insight into block rotations and neotectonic deformation in eastern Asia
Authors: Huang Baochun , Piper John D. A. , Zhang Chunxia , Li Zhenyu , Zhu Rixiang
Published: March 2007

Although first‐order agreement of paleomagnetic directions between south China and Siberia shows that terranes between them were sutured by Cretaceous times, deformation by ongoing tectonism has continued and been especially focused near the continental margin of eastern Asia. To help evaluate differential rotations and relate them to regional strike‐slip and extensional tectonic regimes, we have conducted paleomagnetic study on Cretaceous sediments and volcanic rocks from the Jiaodong Peninsula south of the Bohai Sea in eastern China bordering the Tan‐Lu Fold Zone (TLFZ). Paleomagnetic results from 73 sites in the (Early Cretaceous) Laiyang and Qingshan groups and (Late Cretaceous) Wangshi Group yield magnetizations of primary or synfolding (mid‐Cretaceous) origins. Large differential block rotations of Early Cretaceous age are identified near the Muping‐Jimo Fracture Zone (MJFZ) dissecting the peninsula although Late Cretaceous declinations are regionally systematic and show post‐Late Cretaceous counterclockwise rotation of ∼14° in the Jiaolai Basin relative to the reference North and South China blocks. Block boundaries are identified as the TLFZ to the west and the MJFZ in the southeast. The eastern Jiaodong Peninsula is rotated clockwise relative to the North and South China blocks by a comparable amount (∼20°) to the southern Korean Peninsula to the east and to the Liaodong Peninsula and Yanji Basin to the north. Although these blocks are unlikely to be tightly coupled, their collective clockwise rotation mirrors counterclockwise rotations north of the Japan Sea and probably resulted from regional extension focused above uprise of asthenosphere beneath eastern Asia during Cretaceous times.
Geophysical explanation for the disparity in spreading rates between the Northern and Southern hemispheres
Authors: McCarthy Dennis
Published: March 2007

An interesting characteristic of the Earth, often noticed by schoolchildren, is that it seems out of balance: Oceans dominate the Southern Hemisphere, while continental crust seems to be crowded into the Northern Hemisphere. The cause of this inequity involves the greater number of mid‐ocean spreading ridges and significantly faster spreading rates in the Southern Hemisphere, but no explanation has ever been suggested for this hemispheric disparity in spreading ridges and rates. An examination of east‐west spreading rates and plate motion indicates that the imbalance is due to simple spherical geometry. In the Southern Hemisphere, the system of spreading ridges encircling Antarctica is pushing all of the neighboring plates northward, away from Antarctica. As these plates approach the equator, they begin to occupy larger latitudinal circumferences. This large‐scale northward motion of latitudinal bands of crust to lower latitudes requires significant emplacement of new crustal material to fill up the larger circumferences, resulting in extremely high sum total east‐west spreading rates along those latitudes. Contrariwise, in the Northern Hemisphere the general northward motion of plates away from the equator and toward smaller circumferences has led to a steep drop in spreading rates and the number of active spreading ridges. Sum total east‐west spreading rates along latitudes are correlated with the rate of latitudinal circumferential extension to a significant degree (r = 0.68). The geophysical result of this correlation has been the asymmetric globe that we see today, mostly young and oceanic in the south, mostly old and continental in the north.
Reactive halogen chemistry in volcanic plumes
Authors: Bobrowski N. , von Glasow R. , Aiuppa A. , Inguaggiato S. , Louban I. , Ibrahim O. W. , Platt U.
Published: March 2007

Bromine monoxide (BrO) and sulphur dioxide (SO2) abundances as a function of the distance from the source were measured by ground‐based scattered light Multiaxis Differential Optical Absorption Spectroscopy (MAX‐DOAS) in the volcanic plumes of Mt. Etna on Sicily, Italy, in August–October 2004 and May 2005 and Villarica in Chile in November 2004. BrO and SO2 spatial distributions in a cross section of Mt. Etna's plume were also determined by Imaging DOAS. We observed an increase in the BrO/SO2 ratio in the plume from below the detection limit near the vent to about 4.5 × 10−4 at 19 km (Mt. Etna) and to about 1.3 × 10−4 at 3 km (Villarica) distance, respectively. Additional attempts were undertaken to evaluate the compositions of individual vents on Mt. Etna. Furthermore, we detected the halogen species ClO and OClO. This is the first time that OClO could be detected in a volcanic plume. Using calculated thermodynamic equilibrium compositions as input data for a one‐dimensional photochemical model, we could reproduce the observed BrO and SO2 vertical columns in the plume and their ratio as function of distance from the volcano as well as vertical BrO and SO2 profiles across the plume with current knowledge of multiphase halogen chemistry, but only when we assumed the existence of an “effective source region,” where volcanic volatiles and ambient air are mixed at about 600°C (in the proportions of 60% and 40%, respectively).
A stratospheric ozone profile data set for 1979–2005: Variability, trends, and comparisons with column ozone data
Authors: Randel William J. , Wu Fei
Published: March 2007

A global stratospheric ozone data set for 1979–2005 is described. Interannual variations are derived from analysis of Stratospheric Aerosol and Gas Experiment (SAGE I and II) profile measurements, combined with polar ozonesonde data from Syowa (69°S) and Resolute (75°N). These interannual changes are combined with a seasonally varying ozone climatology from Fortuin and Kelder [1998] to provide a monthly global data set. These data are intended for use in global modeling studies and for analysis of global variability and trends. In order to generate continuous fields from the gappy SAGE data, we use a regression fit that includes decadal trends, solar cycle, and QBO terms, and the spatial structure of these variations is studied in detail. Decadal trends are modeled using an equivalent effective stratospheric chlorine proxy. Ozone variability from the vertically integrated SAGE/sonde data set is compared with results derived from a merged Total Ozone Mapping Spectrometer/solar backscatter ultraviolet column ozone data set, showing good overall agreement (in particular for trends in extratropics). We also compare the SAGE data with ozonesonde measurements over Northern Hemisphere midlatitudes and find excellent agreement for lower stratospheric variability and trends. In the tropics, the SAGE ozone data show relatively large percentage decreases in the lower stratosphere. However, the vertically integrated SAGE data do not agree with column ozone trends in the tropics, so there is less confidence in the SAGE results in this region.
Telomere dysfunction suppresses spontaneous tumorigenesis in vivo by initiating p53‐dependent cellular senescence
Authors: Cosme‐Blanco Wilfredo , Shen Mei‐Feng , Lazar Alexander J F , Pathak Sen , Lozano Guillermina , Multani Asha S , Chang Sandy
Published: March 2007

Dysfunctional telomeres induce p53‐dependent cellular senescence and apoptosis, but it is not known which function is more important for tumour suppression in vivo. We used the p53R172P knock‐in mouse, which is unable to induce apoptosis but retains intact cell‐cycle arrest and cellular senescence pathways, to show that spontaneous tumorigenesis is potently repressed in Terc−/−p53R172P mice. Tumour suppression is accompanied by global induction of p53, p21 and the senescence marker senescence‐associated‐β‐galactosidase. By contrast, cellular senescence was unable to suppress chemically induced skin carcinomas. These results indicate that suppression of spontaneous tumorigenesis by dysfunctional telomeres requires the activation of the p53‐dependent cellular senescence pathway.
Patterns of spiral wave attenuation by low-frequency periodic planar fronts
Authors: de la Casa Miguel A. , de la Rubia F. Javier , Ivanov Plamen Ch.
Published: March 2007

There is evidence that spiral waves and their breakup underlie mechanisms related to a wide spectrum of phenomena ranging from spatially extended chemical reactions to fatal cardiac arrhythmias [A. T. Winfree, The Geometry of Biological Time (Springer-Verlag, New York, 2001); J. Schutze, O. Steinbock, and S. C. Muller, Nature 356, 45 (1992); S. Sawai, P. A. Thomason, and E. C. Cox, Nature 433, 323 (2005); L. Glass and M. C. Mackey, From Clocks to Chaos: The Rhythms of Life (Princeton University Press, Princeton, 1988); R. A. Gray et al., Science 270, 1222 (1995); F. X. Witkowski et al., Nature 392, 78 (1998)]. Once initiated, spiral waves cannot be suppressed by periodic planar fronts, since the domains of the spiral waves grow at the expense of the fronts [A. N. Zaikin and A. M. Zhabotinsky, Nature 225, 535 (1970); A. T. Stamp, G. V. Osipov, and J. J. Collins, Chaos 12, 931 (2002); I. Aranson, H. Levine, and L. Tsimring, Phys. Rev. Lett. 76, 1170 (1996); K. J. Lee, Phys. Rev. Lett. 79, 2907 (1997); F. Xie, Z. Qu, J. N. Weiss, and A. Garfinkel, Phys. Rev. E 59, 2203 (1999)]. Here, we show that introducing periodic planar waves with long excitation duration and a period longer than the rotational period of the spiral can lead to spiral attenuation. The attenuation is not due to spiral drift and occurs periodically over cycles of several fronts, forming a variety of complex spatiotemporal patterns, which fall into two distinct general classes. Further, we find that these attenuation patterns only occur at specific phases of the descending fronts relative to the rotational phase of the spiral. We demonstrate these dynamics of phase-dependent spiral attenuation by performing numerical simulations of wave propagation in the excitable medium of myocardial cells. The effect of phase-dependent spiral attenuation we observe can lead to a general approach to spiral control in physical and biological systems with relevance for medical applications.
Cardiac magnetic field map topology quantified by Kullback-Leibler entropy identifies patients with hypertrophic cardiomyopathy
Authors: Schirdewan A. , Gapelyuk A. , Fischer R. , Koch L. , Schütt H. , Zacharzowsky U. , Dietz R. , Thierfelder L. , Wessel N.
Published: March 2007

Hypertrophic cardiomyopathy (HCM) is a common primary inherited cardiac muscle disorder, defined clinically by the presence of unexplained left ventricular hypertrophy. The detection of affected patients remains challenging. Genetic testing is limited because only in 50%–60% of all HCM diagnoses an underlying mutation can be found. Furthermore, the disease has a varied clinical course and outcome, with many patients having little or no discernible cardiovascular symptoms, whereas others develop profound exercise limitation and recurrent arrhythmias or sudden cardiac death. Therefore prospective screening of HCM family members is strongly recommended. According to the current guidelines this includes serial echocardiographic and electrocardiographic examinations. In this study we investigated the capability of cardiac magnetic field mapping (CMFM) to detect patients suffering from HCM. We introduce for the first time a combined diagnostic approach based on map topology quantification using Kullback-Leibler (KL) entropy and regional magnetic field strength parameters. The cardiac magnetic field was recorded over the anterior chest wall using a multichannel-LT-SQUID system. CMFM was calculated based on a regular 36 point grid. We analyzed CMFM in patients with confirmed diagnosis of HCM (HCM, n=33, 43.8±13 years, 13 women, 20 men), a control group of healthy subjects (NORMAL, n=57, 39.6±8.9 years; 22 women and 35 men), and patients with confirmed cardiac hypertrophy due to arterial hypertension (HYP, n=42, 49.7±7.9 years, 15 women and 27 men). A subgroup analysis was performed between HCM patients suffering from the obstructive (HOCM, n=19) and nonobstructive (HNCM, n=14) form of the disease. KL entropy based map topology quantification alone identified HCM patients with a sensitivity of 78.8% and specificity of 86.9% (overall classification rate 84.8%). The combination of the KL parameters with a regional field strength parameter improved the overall classification rate to 87.9% (sensitivity: 84.8%, specificity: 88.9%, area under ROC curve: 0.94). KL measures applied to discriminate between HOCM and HNCM patients showed a correct classification of 78.8%. The combination of one KL and one regional parameter again improved the overall classification rate to 97%. A preliminary prospective analysis in two HCM families showed the feasibility of this diagnostic approach with a correct diagnosis of all 22 screened family members (1 HOCM, 4 HNCM, 17 normal). In conclusion, Cardiac Magnetic Field Mapping including KL entropy based topology quantifications is a suitable tool for HCM screening.
Structural and magnetic studies of Co layer in epitaxially grown Fe∕Co bilayers
Authors: Wang S. G. , Wang C. , Kohn A. , Lee S. , Goff J. P. , Singh L. J. , Barber Z. H. , Ward R. C. C.
Published: March 2007

Epitaxial Fe∕Co bilayers were grown on MgO (001) substrates by molecular beam epitaxy, characterized in situ by reflection high-energy electron diffraction and ex situ by x-ray diffraction (XRD), as well as high-resolution transmission electron microscopy (HRTEM). The hexagonal close packed (hcp) structure in two perpendicular domains was identified for the Co layer using XRD and HRTEM techniques. Co is found to grow in the (11−20) orientation with the c axis in plane, parallel either to Fe[110] or Fe[1−10] The magnetic properties as a function of Co thickness in Fe (10nm)∕Co (t) (t=5–20nm) bilayers were investigated. The Fe∕Co bilayers exhibit in plane magnetization with easy axes parallel to Fe[100] and Fe[010] axes. The magnetic behavior is consistent with the orientation relationship between the Fe and Co layers.
Atom probe tomography
Authors: Kelly Thomas F. , Miller Michael K.
Published: March 2007

The technique of atom probe tomography (APT) is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future. APT delivers the highest spatial resolution (sub-0.3-nm) three-dimensional compositional information of any microscopy technique. Recently, APT has changed dramatically with new hardware configurations that greatly simplify the technique and improve the rate of data acquisition. In addition, new methods have been developed to fabricate suitable specimens from new classes of materials. Applications of APT have expanded from structural metals and alloys to thin multilayer films on planar substrates, dielectric films, semiconducting structures and devices, and ceramic materials. This trend toward a broader range of materials and applications is likely to continue.
L
2
-compact uniform attractors for a nonautonomous incompressible non-Newtonian fluid with locally uniformly integrable external forces in distribution space
Authors: Zhao Caidi , Zhou Shengfan
Published: March 2007

We consider the long-time behavior of solutions for a two-dimensional nonautonomous incompressible non-Newtonian fluid with external forces in distribution space. When the external force g0(x,t) is locally uniformly integrable (see Definition 3.1) in Lloc2(R;W′), we prove the existence of L2-compact uniform attractor in space H and reveal its structure for the families of processes corresponding to the fluid. Moreover, if ∥g0∥Lb2(R;W′) is properly small, we establish the unique existence of bounded asymptotically stable solutions and give two interesting corollaries.
Defect-induced charge-order melting in thin films of Pr0.5Ca0.5MnO3
Authors: Zhang Y. Q. , Zhu Y. L. , Zhang Z. D. , Aarts J.
Published: March 2007

We have investigated the relation between defect structure and charge order melting in thin films of epitaxial Pr0.5Ca0.5MnO3 (PCMO), grown under strain on SrTiO3. We compared the behavior of an 80nm film grown in one deposition step at 840°C with the behavior of a film grown in two steps. In the two-step case, a thin PCMO layer of 10nm was deposited at 120°C, followed by 70nm deposited at 840°C. The increase of the growth temperature leads to complete crystallization of the first layer and the lattice constants of the two-step grown film indicate that tensile strain is still present. On the other hand, a magnetic field of only 5T is required to melt the charge-order state in the two-step grown film, which is a much lower than the value for the normally grown film. This appears to be connected to a larger amount of threading dislocations present in the first (recrystallized) layer.
Ab initio prediction of the low-temperature phase diagrams in the systems KBr–NaBr, KX–RbX, and LiX–RbX (X=Cl,Br)
Authors: Pentin I. V. , Schön J. C. , Jansen M.
Published: March 2007

The authors have calculated the low-temperature phase diagrams for the ternary alkali halides KBr–NaBr, KX–RbX, and LiX–RbX (X=Cl,Br) systems on the ab initio level without any recourse to experimental information. Via global exploration of the enthalpy landscapes for many different compositions in these systems, candidates for both ordered stoichiometric modifications and crystalline solid solution phases have been identified. Next, their free enthalpies were computed on ab initio level, and the respective low-temperature phase diagram has been derived. They find miscibility gaps in the systems KBr–NaBr and KX–RbX (X=Cl,Br), while in LiX–RbX (X=Cl,Br) only crystalline ordered phases should be present, in agreement with available experimental data. Furthermore, they predict several new thermodynamically stable and metastable phases in these systems.
Raman and x-ray diffraction studies of Ba doped germanium clathrate Ba8Ge43 at high pressures
Authors: Shimizu Hiroyasu , Iitaka Toshiaki , Fukushima Takumi , Kume Tetsuji , Sasaki Shigeo , Sata Nagayoshi , Ohishi Yasuo , Fukuoka Hiroshi , Yamanaka Shoji
Published: March 2007

High-pressure Raman and x-ray diffraxtion (XRD) measurements of a defect clathrate Ba8Ge43◻3 have been carried out at room temperature up to 40 GPa. Three vibrational modes associated with guest Ba atoms were observed in the low-frequency region, and the structureless spectrum due to Ge vacancies was found in the framework vibrational region. The Raman spectra shows a pressure-induced phase transition at 8 GPa, which is due to the structural distortion through the three-bonded Ge atoms and to the change in the guest-host electronic interaction. Both Raman spectra and XRD patterns present the evidence for the amorphization of Ba8Ge43 around 30–40 GPa. The isostructural phase transition often present in intercalated silicon clathrates and associated with a large volume reduction was not observed for Ba8Ge43 up to 40 GPa. The pressure dependence of the lattice constant (a) normalized by a0 at 1 bar (a∕a0) shows the continuous decrease with pressure until amorphization. From the good coincidence of this curve between Ba8Ge43 and Ba8Si46 at pressures above 15 GPa, we propose that the isostructural phase transition found for Ba8Si46 at 15 GPa may be originated from a defect-induced transformation to Ba8Si43◻3 with the help of their theoretical equation of state by the first-principles calculations.
Resistance maps from local probing of a ballistic mesoscopic Hall bar
Authors: Papp G. , Peeters F. M.
Published: March 2007

The response of a ballistic mesoscopic Hall bar to a local potential barrier is investigated in the presence of an external magnetic field. The effect of the position of the local potential probe in the Hall cross on the Hall and bend resistance is investigated leading to two-dimensional (2D) resistance maps. The Onsager–Casimir symmetry relations and symmetry relations between resistance measurements when interchanging the current and voltage leads, is obtained numerically for such 2D resistance maps. Symmetry properties are derived for the Hall and bend resistance maps with respect to the position of the local potential barrier.
Excitation of terahertz radiation by laser pulses in nonuniform plasma channels
Authors: Antonsen Thomas M. , Palastro John , Milchberg Howard M.
Published: March 2007

The excitation of terahertz radiation by laser pulses propagating in miniature plasma channels is considered. Generation of radiation by laser pulses in uniform plasmas is generally minimal. However, if one considers propagation in corrugated plasma channels, conditions for radiation generation can be met due to the inhomogeneity of the channel and the presence of guided waves with subluminal phase velocities. It is found that for channels and laser pulses with parameters that can be realized today, energy conversion rates of a fraction of a joule per centimeter can be achieved. Miniature corrugated channels can also be used for creation of THz radiation by bunched electron beams.
Statistical physics approach to categorize biologic signals: From heart rate dynamics to DNA sequences
Authors: Peng C.-K. , Yang Albert C.-C. , Goldberger Ary L.
Published: March 2007

We recently proposed a novel approach to categorize information carried by symbolic sequences based on their usage of repetitive patterns. A simple quantitative index to measure the dissimilarity between two symbolic sequences can be defined. This information dissimilarity index, defined by our formula, is closely related to the Shannon entropy and rank order of the repetitive patterns in the symbolic sequences. Here we discuss the underlying statistical physics assumptions of this dissimilarity index. We use human cardiac interbeat interval time series and DNA sequences as examples to illustrate the applicability of this generic approach to real-world problems.
Landau damping of dust acoustic waves in a Lorentzian plasma
Authors: Lee Myoung-Jae
Published: March 2007

The Landau damping of dust acoustic waves propagating in a dusty plasma modeled by a Lorentzian (kappa) distribution for electrons and ions, and by a Maxwellian distribution for the dust grains is kinetically investigated. The dust acoustic waves are found in the range of kvd≪ω≪kvi≪kve, where vα is the thermal velocity of species α(=i,e,d). The damping rate is shown to be dependent on the spectral index κ as well as the ratio of ion density to electron. The maximum Landau damping rate is derived and found to be approximately 0.2σκωpd where ωpd is the dust plasma frequency and σκ is a κ-dependent factor, which has the maximum value of 1.33 (for the smallest κ) and reduces to unity as the nonthermal effect disappears.
Shock velocity in weakly ionized nitrogen, air, and argon
Authors: Siefert Nicholas S.
Published: March 2007

The goal of this research was to determine the principal mechanism(s) for the shock velocity increase in weakly ionized gases. This paper reports experimental data on the propagation of spark-generated shock waves (1<Mach<3) into weakly ionized nitrogen, air, and argon glow discharges (1<p<20Torr). In order to distinguish between effects due solely to the presence of electrons and effects due to heating of the background gas via elastic collisions with electrons, the weakly ionized discharge was pulsed on/off. Laser deflection methods determined the shock velocity, and the electron number density was collected using a microwave hairpin resonator. In the afterglow of nitrogen, air, and argon discharges, the shock velocity first decreased, not at the characteristic time for electrons to diffuse to the walls, but rather at the characteristic time for the centerline gas temperature to equilibrate with the wall temperature. These data support the conclusion that the principal mechanism for the increase in shock velocity in weakly ionized gases is thermal heating of the neutral gas species via elastic collisions with electrons.
Optical geometries for fiber-based organic photovoltaics
Authors: Liu Jiwen , Namboothiry Manoj A. G. , Carroll David L.
Published: March 2007

Poly(3-hexylthiophene):1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 photovoltaic devices were fabricated as a cladding onto large diameter optical fibers. The performance of the devices was dependent on fiber diameter as well as the angle of incidence of light onto the cleaved fiber face. The authors suggest that absorption by the active layer is dominated by different mechanisms at different angles: evanescent coupling of the light at small incident angles and far field scattering of the light from the fiber at higher angles. Further, a comparison of devices that only partially clad the fiber to those that fully clad suggests the formation of confined radiation modes.
Free vibration analysis of fluid-conveying single-walled carbon nanotubes
Authors: Reddy C. D. , Lu C. , Rajendran S. , Liew K. M.
Published: March 2007

The effect of fluid flow on the free vibration and instability of fluid-conveying single-walled carbon nanotubes is studied. The possibility of developing a technique to measure the mass flow rate of fluid is examined. Atomistic simulations and the continuum beam model are used. Simulations are performed to quantify the inertial, stiffness, Coriolis, and centrifugal forces generated by flow during the free vibration. A numerical expression is developed to measure the mass flow rate of the fluid velocities up to 40% of the critical flow velocity. This observation is useful to quantify the mass flow measurement of fluid conveying single-walled carbon nanotubes.
Coercivity and nanostructure in magnetic spinel Mg(Mn,Fe)2O4
Authors: Zhang C. L. , Yeo S. , Horibe Y. , Choi Y. J. , Guha S. , Croft M. , Cheong S.-W. , Mori S.
Published: March 2007

When Fe ions in the ferrimagnetic cubic MgFe2O4 are replaced by Jahn-Teller (JT)-active Mn ions, the structure evolves with two-step processes. For example, the quenched cubic MgMn1.5Fe0.5O4 becomes tetragonal and JT distorted with slow cooling. However, with further slow cooling, the clustering tendency of JT-distorted Mn ions induces the formation of a checkerboard nano-self-assembly consisting of Mn-rich (tetragonal, paramagnetic) and -poor (cubic, ferrimagnetic) rods. This morphological evolution accompanies a drastic modification of ferrimagnetic properties, e.g., the magnetic coercivity changes by ∼25. The nanocheckerboard assembly with ferrimagnetic nanorods with large shape anisotropy can be a platform for ultra high-density memory devices.
Introduction: Cardiovascular physics
Authors: Wessel Niels , Kurths Jürgen , Ditto William , Bauernschmitt Robert
Published: March 2007

The number of patients suffering from cardiovascular diseases increases unproportionally high with the increase of the human population and aging, leading to very high expenses in the public health system. Therefore, the challenge of cardiovascular physics is to develop high-sophisticated methods which are able to, on the one hand, supplement and replace expensive medical devices and, on the other hand, improve the medical diagnostics with decreasing the patient’s risk. Cardiovascular physics–which interconnects medicine, physics, biology, engineering, and mathematics–is based on interdisciplinary collaboration of specialists from the above scientific fields and attempts to gain deeper insights into pathophysiology and treatment options. This paper summarizes advances in cardiovascular physics with emphasis on a workshop held in Bad Honnef, Germany, in May 2005. The meeting attracted an interdisciplinary audience and led to a number of papers covering the main research fields of cardiovascular physics, including data analysis, modeling, and medical application. The variety of problems addressed by this issue underlines the complexity of the cardiovascular system. It could be demonstrated in this Focus Issue, that data analyses and modeling methods from cardiovascular physics have the ability to lead to significant improvements in different medical fields. Consequently, this Focus Issue of Chaos is a status report that may invite all interested readers to join the community and find competent discussion and cooperation partners.
Effect of grain size and pores on the dielectric constant of nanocrystalline diamond films
Authors: Wang Z. L. , Li J. J. , Sun Z. H. , Li Y. L. , Luo Q. , Gu C. Z. , Cui Z.
Published: March 2007

The nanocrystalline diamond films with different morphologies and roughness were synthesized by a bias-assisted hot filament chemical vapor deposition method. It was found that the nanocrystalline diamond film exhibited low-k dielectric properties with the increase of CH4 concentration during diamond deposition. The low-k nanocrystalline diamond film with grain size of around 40nm and dielectric constant of 2.4 was obtained at the CH4 concentration of 16% and the bias of −140V. The low dielectric constant can be mainly attributed to the decrease of diamond grain sizes and the formation of more nanopores in as-grown nanocrystalline diamond film, both of which were discussed in details based on the grain size determined band gap expansion effect and the two-phase dielectric mixing model, respectively.
Amorphous Si∕Au wafer bonding
Authors: Chen P. H. , Lin C. L. , Liu C. Y.
Published: March 2007

The authors report a rapid reaction between Au and amorphous Si (a-Si), which occurred at a much faster rate compared to the case of crystal Si∕Au reaction. With an amorphous Si coating layer on crystal Si (c-Si) wafer, air voids and craters were prevented from forming at the Si∕Au bonding interface, but were usually found at the crystal Si∕Au bonding interface. The uniform liquid eutectic Au–Si alloy quickly formed at the Au/amorphous Si bonding interface is the key for the prevention of air voids and craters. This amorphous Si∕Au bonding process enables the feasibility of eutectic Au∕Si bonding for wafer bonding applications.
Mechanics of precisely controlled thin film buckling on elastomeric substrate
Authors: Jiang Hanqing , Sun Yugang , Rogers John A. , Huang Yonggang
Published: March 2007

Stretchable electronics has many important and emerging applications. Sun et al. [Nature Nanotech. 1, 201 (2006)] recently demonstrated stretchable electronics based on precisely controlled buckle geometries in GaAs and Si nanoribbons on elastomeric substrates. A nonlinear buckling model is presented in this letter to study the mechanics of this type of thin film/substrate system. An analytical solution is obtained for the buckling geometry (wavelength and amplitude) and the maximum strain in buckled thin film. This solution agrees very well with the experiments, and shows explicitly how buckling can significantly reduce the thin film strain to achieve the system stretchability.
Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals
Authors: Huang Lihui , Yamashita Tatsuya , Jose Rajan , Arai Yusuke , Suzuki Takenobu , Ohishi Yasutake
Published: March 2007

A transparent Tb3+ and Yb3+ codoped oxyfluoride glass ceramic containing CaF2 nanocrystals was developed. This glass ceramic showed an intense ultraviolet emission at 381nm due to the G65, D35→F67 transitions of Tb3+ ion when excited with a 974nm laser at room temperature. The observed intense ultraviolet emission could be attributed to the change of ligand field of Tb3+ and Yb3+ ions due to the incorporation of some Tb3+ and Yb3+ ions into CaF2 nanocrystals, and the resulting increased branching ratio of the transitions and longer lifetime of D45 level of Tb3+ in the glass ceramic.
Pulsed ion-beam induced nucleation and growth of Ge nanocrystals on SiO2
Authors: Stepina N. P. , Dvurechenskii A. V. , Armbrister V. A. , Kesler V. G. , Novikov P. L. , Gutakovskii A. K. , Kirienko V. V. , Smagina Zh. V. , Groetzschel R.
Published: March 2007

Pulsed low-energy (200eV) ion-beam induced nucleation during Ge deposition on thin SiO2 film was used to form dense homogeneous arrays of Ge nanocrystals. The ion-beam action is shown to stimulate the nucleation of Ge nanocrystals when being applied after thin Ge layer deposition. Temperature and flux variation was used to optimize the nanocrystal size and array density required for memory device. Kinetic Monte Carlo simulation shows that ion impacts open an additional channel of atom displacement from a nanocrystal onto SiO2 surface. This results both in a decrease in the average nanocrystal size and in an increase in nanocrystal density.
Supply-Side Policies and Retail Property Market Performance
Authors: Jackson Catherine , Watkins Craig
Published: March 2007

In this paper we are concerned with the relationship between the government's supply-side policies, including development control regimes, and the performance of the retail property market. It is argued that the regulatory environment impacts on the prices paid by both users and owners of retail space. This assertion is tested empirically. A range of measures of the complex and, at times, conflicting supply-side policies are incorporated into models of retail market values. The models are estimated using data for a cross-section of British cities and cover the period from 1998 to 2003. The results show that planning policy intervention has a more pronounced impact on the investor market than the user market. It seems that a proactive policy environment, with a strong emphasis on towncentre management and improvements to the shopping environment, will exert a significant influence on retail capital values and yields. These factors are less likely to impact on the rents paid by retailers who appear to be more concerned with representation across major markets and are less sensitive to differences in local policy stance.
Urban Societies and Dominant Political Coalitions in the Internationalization of Cities
Authors: Jouve Bernard
Published: March 2007

We are facing a transformation of the political order in which cities are becoming more and more important, partly in the field of economic development but also regarding security questions, specifically after 9 September 2001, such as cultural diversity, social cohesion, and sustainable development. The institutional conditions of governability have evolved during the last two decades. Cities develop strategies at the global level and promote different kinds of collective value. In this paper we aim to analyse these international strategies, their elaboration, and their implementation by using a comparison of Montreal, Paris, and Rome. The various strategies are analyzed as the outcome of dominant political coalitions between the political institutions and very specific segments of civil society.
Local Economic Development in Sub-Saharan Africa
Authors: Rodríguez-Pose Andrés , Tijmstra Sylvia A R
Published: March 2007

It has often been argued that Africa in general, and Sub-Saharan Africa (SSA) in particular, is ‘different’ and that it therefore requires ‘exceptional’ solutions to its development problems. In contrast, in this paper we argue that strong internal heterogeneity combined with general trends similar to those experienced elsewhere in the world make local economic development (LED) as likely to succeed in SSA as in other low- and middle-income countries. The likelihood of success depends mostly on place-specific conditions. Many of the most prosperous parts of the continent already have the basic enabling conditions for the design and implementation of LED strategies in place. Less favourable resource endowments, poor accessibility, and relatively weak civil societies can undermine the viability of LED outside the wealthier and most prosperous areas. In smaller urban areas and intermediate regions and city-regions, which lack only a few of the basic preconditions for LED, further capacity building may still enable the success of the approach. In contrast, LED may not be relevant for the poorest and most remote parts of SSA, where existing conditions do not provide a strong enough base on which to build LED strategies.
Identity, Mobility, and the Throwaway Society
Authors: Gregson Nicky , Metcalfe Alan , Crewe Louise
Published: March 2007

This paper provides a critique of the concept of the throwaway society. Drawing on two years of intensive qualitative research, we argue that the concept of the throwaway society does not bear scrutiny. Rather than throwing things away households are shown consistently to engage in simultaneous practices of saving and wasting when getting rid of consumer objects. Saving and wasting are shown to be critical to materialising identities and the key social relations of family and home. Focusing on self, the couple relation, and the mother–child relation, we show how wasting things is intimately connected to the narration of self and to the enactment of specific love relations. The paper also shows how wasting things is central to moving home, constituting a surplus and then an excess of household possessions. The paper concludes by arguing that to understand the increasing amount of matter being turned to waste in the UK requires a focus on love relations and mobility, and not on the trajectories of things themselves.