bluuebunny/crossref_metadata_2025 huggingface dataset:
Management of leukaemia and allied haematological disorders in homœopathy
Authors: Pareek R.S.
Published: September 2006

A brief look is taken at the history, classification, pathology and present-day clinical presentation of the group of diseases referred to as ‘leukaemia and allied haematological disorders’. Their management is discussed and illustrated with case histories. Following in the footsteps of the Master, we have many opportunities to procure palliation and cure. It is suggested that Hahnemann's theory of miasm is perfectly rational in the light of modern medicine.
Determination of neutralization point for allergic hypersensitivity
Authors: Fox Anthony D.
Published: September 2006

The electronic Vegatest method of determining environmental hypersensitivities (allergies) is fast, accurate, and does not require the use of any needle puncture of the skin of the patient. It provides a relatively reliable method of determining the neutralization point and is well suited to the use of homœopathic medicines.
A study of serum electrolyte and thyroid hormone changes in Iodum provers
Authors: Vakil V.E. , Nanabhai A.S. , Vakil A.E.
Published: September 2006

An attempt was made to evaluate changes of serum Na+, K+, T3 and T4 in healthy provers after treatment with Iodum. Iodum 12x was administered to a group of 11 healthy female students for 21 days. Serum Na+, K+, T3 and T4 were estimated before exhibition of the drug, and on the 11th and the last day of the trial. T3 showed an increase by 20% and T4 by 5%. Both Na+ and K+ were found to decrease, Na+ by 2%, K+ by 6%.
Menieres disease treated with chenopodium
Authors: Jack R.A.F.
Published: September 2006

The patient presented was a 54-year-old man who had suffered from frequent disabling attacks on Menieres for three years, for which no conventional treatment had been effective, and who has not had a single attack in the last eighteen months, since starting treatment with homœopathic Chenopodium. He has been under regular hospital surveillance all this time.
Choice of potency homœopathic prescribing
Authors: Voegeli Adolf
Published: September 2006

The nature of potencies is considered, with a critical review of high and low potency prescribing for acute and chronic diseases.
The expectations, health beliefs and behaviour of patients seeking homœopathic and conventional medicine
Authors: Hewison Jenny , Davies Peter , Pietroni Patrick , Harrison Clare
Published: September 2006

Research was carried out to determine whether or not there was a difference in the health beliefs, expectations and behaviour of a sample of 92 patients attending a dermatological or rheumatological outpatient clinic which offered either homœopathic treatment (N=47) or conventional treatment (N=45).

Self-administered questionnaires were used which examined patients' pathways to care, expectations, beliefs, behaviour and multidimensional health locus of control.

The two key differences between those seeking homœopathic and those seeking conventional medicine were in terms of (1) their reasons for attending a homœopathic or conventional clinic, and (2) their beliefs about their presenting dermatological or rheumatological condition.
Democracy and Gender Inequality in Education: A Cross-National Examination
Authors: BROWN DAVID S.
Published: September 2006

This Research Note examines the role democracy plays in explaining the disparity in educational attainment between men and women in a cross-national context. Policies designed to improve education figure prominently in recent attempts by governments, international institutions and non-governmental organizations (NGOs) to stimulate economic development. The recent emphasis on education is grounded in a well-established literature in economics on the rate of return on investment in education and in a fairly new stream of research in economics – endogenous growth theory – that suggests knowledge is the generative force of economic growth. Although a majority of the work in both literatures focuses on aggregate levels of educational attainment (usually enrolment ratios or literacy rates), a growing body of evidence identifies women’s educational attainment relative to men’s as a crucial variable in explaining the wide variation in economic development throughout the world. In addition to its direct impact on economic growth, women’s education may indirectly affect economic performance in a number of important ways: through its impact on health, fertility and infant mortality. Previous empirical work shows that women’s education has a strong negative effect on fertility and infant mortality. Moreover, family health practices improve in direct proportion to female education. According to the World Bank, countries that achieved universal primary education for boys in 1965 but lagged far behind in educating girls had about twice the infant mortality and fertility rates in 1985 of countries with smaller gender gaps.
Electoral Systems and Proportional Tenure of Government: Renewing the Debate
Authors: VOWLES JACK
Published: September 2006

Debates between advocates of the two major alternative forms of electoral system often proceed at cross-purposes. In parliamentary systems, governments not only wield executive power, they strongly influence the agenda of the legislature and in some cases dominate it. The core literature on electoral systems focuses almost entirely on the relations between vote shares and legislative seat shares, leaving government formation aside. Yet the main debate about democratic accountability focuses on representative government, of which a representative legislature is at most only one part.
Evaluation of management strategies for sustainable rice–wheat cropping system, using DSSAT seasonal analysis
Authors: SARKAR R. , KAR S.
Published: September 2006

A simulation study using the Seasonal Analysis program of the Decision Support Systems for Agrotechnology Transfer (DSSAT 3.5) suite of models was conducted from 2001 to 2003 under a subhumid subtropical climate. The models CERES-Rice and CERES-Wheat in DSSAT 3.5 were calibrated and validated for transplanted rice, direct seeded rice and wheat crops using the soil and weather parameters of Kharagpur, West Bengal, India. The weather generator program, SIMMETEO, was used to generate future weather scenarios based on weather data from 9 consecutive years. These weather scenarios were used in the seasonal analysis program to run each treatment combination with 20 replications. The results of both biophysical and economic analyses of the Seasonal Analysis program predicted an application of 120 kg N/ha along with both rice and wheat crop residues at 4 t/ha for rice, whereas the economical analysis, specifically the Mean-Gini analysis, showed that application of 80 kg N/ha along with both rice and wheat crop residue incorporation at 4 t/ha as the most dominant management options for wheat. The present study revealed that the generated future weather data were reliable and DSSAT could successfully use it to predict the future crop yields under different management practices and select the best one for sustainable production of rice and wheat crops by DSSAT.
Proposal of a new principle of cyclotron emission from neutralized electron beams
Authors: MINAMI KAZUO , CHOYAL YADUVENDRA , WATANABE TSUGUHIRO
Published: September 2006

Radiation from a loosely constrained cyclotron motion of mono-energetic electrons on a common large orbit (LO) circle in a uniform axial magnetic field and in a right-hand circularly polarized field of plane electromagnetic waves has been studied numerically by particle simulation. A restoring force caused by neutralizing ions against the displacements of gyrating electrons from the original LO circle is introduced by a phenomenological potential well in the radial direction. It is shown that, in high-density beams such as ωb2 ≫~Ω2, Cherenkov instability in the azimuthal direction with ω <~ω+Vzkz leads to the excitation of microwaves. Here, ωb, ~ω, ω, Vz and kz are, respectively, relativistic beam plasma frequency, relativistic electron cyclotron frequency, oscillation angular frequency, axial component of beam velocity and axial wavenumber.
Preparedness for a smallpox outbreak: comparing metrics for assessing levels of vaccination among health-care workers by state
Authors: BASS S. B. , RUZEK S. B. , GORDON T. F. , HANLON A. L.
Published: September 2006

By mid-2005, less than 17% of smallpox vaccine doses distributed to American states for health-care workers (HCWs) during the CDC campaign had been used. To understand how states responded, vaccination patterns were studied. Metrics were calculated to compare the level of preparedness for a smallpox outbreak in terms of absolute numbers of HCWs vaccinated compared to the percentage of doses distributed to each state, the rate of vaccination per capita population, and the percentage of HCWs vaccinated compared to the number the CDC recommended. States were then ranked. Results showed that rankings for all four metrics were statistically different (P<0·0001). In addition, when ranks were assigned to quartiles, the states directly affected on 9/11/01 ranked lowest and states widely perceived to be at lower terror risk ranked in the top. These results underscore the need to critically examine how to define an appropriate level of preparedness for a smallpox outbreak.
Co2+, Cu2+, and Zn2+ Accumulation by Cyanobacterium Spirulina platensis
Authors: Vannela Raveender , Verma Sanjay Kumar
Published: September 2006

The Spirulina platensis biomass was characterized for its metal accumulation as a function of pH, external metal concentration, equilibrium isotherms, kinetics, effect of co‐ions under free (living cells, lyophilized, and oven‐dried) and immobilized (Ca‐alginate and polyacrylamide gel) conditions. The maximum metal biosorption by S. platensis biomass was observed at pH 6.0 with free and immobilized biomass. The studies on equilibrium isotherm experiments showed highest maximum metal loading by living cells (181.0 ± 13.1 mg Co2+/g, 272.1 ± 29.4 mg Cu2+/g and 250.3 ± 26.4 mg Zn2+/g) followed by lyophilized (79.7 ± 9.6 mg Co2+/g, 250.0 ± 22.4 mg Cu2+/g and 111.2 ± 9.8 mg Zn2+/g) and oven‐dried (25.9 ± 1.9 mg Co2+/g, 160.0 ± 14.2 mg Cu2+/g and 35.1 ± 2.7 mg Zn2+/g) biomass of S. platensis on a dry weight basis. The polyacrylamide gel (PAG) immobilization of lyophilized biomass found to be superior over Ca‐alginate (Ca‐Alg) and did not interfere with the S. platensis biomass biosorption capacity, yielding 25% of metal loading after PAG entrapment. The time‐dependent metal biosorption in both the free and immobilized form revealed existence of two phases involving an initial rapid phase (which lasted for 1–2 min) contributing 63–77% of total biosorption, followed by a slower phase that continued for 2 h. The metal elution studies conducted using various reagents showed more than 90% elution with mineral acids, calcium salts, and Na2EDTA with free (lyophilized or oven‐dried) as well as immobilized biomass. The experiments conducted to examine the suitability of PAG‐immobilized S. platensis biomass over multiple cycles of Co2+, Cu2+, and Zn2+ sorption and elution showed that the same PAG cubes can be reused for at least seven cycles with high efficiency.
Determination of Biomass Composition of Catharanthusroseus Hairy Roots for Metabolic Flux Analysis
Authors: Sriram Ganesh , González‐Rivera Omar , Shanks Jacqueline V.
Published: September 2006

Metabolic flux analysis is a powerful diagnostic tool in metabolic engineering, and determination of biomass composition is indispensable to accurate flux evaluation. We report the elemental and biomolecular composition of Catharanthus roseus hairy roots, a pharmaceutically significant plant system and an important metabolic engineering target. The molecular formula of the organic material in the hairy roots was C12.0H22.7N0.4O7.6 during mid‐exponential growth. The abundances of lipids, lignin, cellulose, hemicellulose, starch, protein, proteinogenic amino acids, mineral ash, and moisture in the biomass were quantified. Analysis of water‐soluble components of the biomass with 1‐D 13C and 2‐D [1H,1H] correlation (COSY) NMR spectroscopy revealed that the water‐soluble components were composed almost entirely of β‐glucans. Agropine, a frequently reported hairy root biomass component, was not detected. Our measurements of the biomass components quantified 83.6 ± 9.3% (w/w) of the biomass. Together with previously reported abundances of indole alkaloids, we accounted for at least 85.9 ± 11.6% (w/w) of the carbon in the biomass, which enabled the precise determination of 12 biomass synthesis fluxes.
Microengineered Surface Topography Facilitates Cell Grafting from a Prototype Hydrogel Wound Dressing with Antibacterial Capability
Authors: Smith Annie G. , Din Abbas , Denyer Morgan , Crowther Nicholas J. , Eagland Donald , Vowden Kath , Vowden Peter , Britland Stephen T.
Published: September 2006

Skin wounds derive therapeutic benefit from redeployment of dermal tissues, whether as split‐thickness allo‐ and autografts or as biological dressings comprising cultured cells. However, the clinical outcome is strongly influenced by the techniques used for cell/tissue grafting and also the microbiological status of the wound. Here we report that microtopography incorporated into the surface of a novel polymeric material, derivatized with fibronectin to promote attachment and encourage motility, improved the efficiency of cell transfer onto de‐epithelialized human skin ex vivo. The microtopography had two functions, first as a conduit for migrating cells to cross between the vehicle and recipient surface and second to shield adherent cells from destruction by mechanical shearing during handling and application. Quantitative analysis showed that topographic projections (columns) rather than recesses (pits) in the hydrogel surface achieved the highest efficiency of cell transfer. In order to address the crucial relevance of microbiological contamination to the success of wound grafting, the effect of iodine on several common bacterial pathogens was examined using an XTT+CQ10 kinetic cell viability assay. Increasing concentrations of iodine initially stressed and after 0.5% v/v were subsequently bacteriocidal for Gram‐negative Pseudomonas aeruginosa and Escherichia coli and Gram‐positive Bacillus subtillis and Staphylococcus aureus. Slightly higher doses of iodine (approx 1–1.5% v/v) were required to kill HaCaT cells outright, but for both pro‐ and eukaryotes the major determinant of cytotoxicity was absolute dose rather than duration of exposure. Iodine delivered by the hydrogel at low concentration was bacteriostatic but not apparently cytotoxic to epithelial cells as measured by MTT end‐point cell viability assay. Zone of inhibition studies confirmed that bacteriocidal quantities of neomycin, phenol red, and silver could also be delivered using the same hydrogel. This research suggests that grafting cell‐based biological dressings to wounds using a topographically modified hydrogel dressing capable of simultaneous reducing the microbiological threat to a successful outcome may be a realistic clinical proposition.
Glacial deep water carbonate chemistry inferred from foraminiferal Mg/Ca: A case study from the western tropical Atlantic
Authors: Fehrenbacher Jennifer , Martin Pamela A. , Eshel Gidon
Published: September 2006

We explore using changes in planktonic foraminiferal Mg/Ca with water depth in a single region to infer relative changes in deep water carbonate chemistry. The Mg/Ca ratio in foraminiferal calcite is quantitatively lowered by dissolution. We exploit this dissolution effect to generate a profile of carbonate ion concentration (CO32−) for the deep waters of the tropical Atlantic during the Last Glacial Maximum. We generated Mg/Ca data for three species, G. ruber, G. sacculifer, and N. dutertrei, from three cores located along a depth transect (2.8 to 4.0 km) on the Ceara Rise in the western equatorial Atlantic. We attribute lower Mg/Ca in glacial intervals from the shallow core to changes in sea surface temperature (SST). The even lower glacial Mg/Ca values in the deeper cores are attributed to dissolution and are used to reconstruct a paleo‐CO32− profile. Our down core Mg/Ca data for G. ruber and G. sacculifer confirm that these species are more resistant to Mg loss due to dissolution than N. dutertrei. The greater susceptibility of N. dutertrei's Mg content to dissolution limits the utility of this species in thermocline temperature reconstructions to cores above the lysocline but, significant to this study, makes N. dutertrei useful in quantifying changes in deep water CO32−. Our paleo‐CO32− reconstruction based on N. dutertrei suggests the Last Glacial Maximum CO32− gradient in the Atlantic was much steeper than today, implying that the boundary between deepwater masses in the Atlantic was shallower during the Last Glacial Maximum. Our results suggest comparison of Mg/Ca from multiple cores from one region could similarly provide constraints on changes in carbonate chemistry in other basins and other time periods.
Standing regular wave groups with oblique incidence: Phase averaging and bottom boundary layer in constant depth
Authors: Sánchez‐Badorrey E. , Losada M. A.
Published: September 2006

This article analyzes the phase‐averaged hydrodynamics induced by regular wave groups and the related long waves under reflective conditions outside of the wave‐breaking zone. The solutions of the inviscid region and wave‐group bottom boundary layer (WGBL) are analytically investigated for a regular wave group at a constant depth, impinging obliquely on an alongshore uniform reflective wall. The problem is formulated and solved by using the classical multiple‐scale approach. Phase averaging is defined on the basis of the cascade of spatial and temporal scales of the problem leading to a weak unsteady (hydrodynamic) regime (WUR), a steady regime (SR), weak nonhomogeneous regime (WNHR), and homogeneous regime (HR) of instantaneous quantities. The analysis of the inviscid region hydrodynamics shows that depending on the time scale used for the averaging, modulation scales of O(100 m) and O(1 km) may appear in the time‐averaged pressure and the free stream velocity fields. These modulations are related to the nonlinear interference of the incoming and reflected wave‐group motions. Supermodulation scales of O(10 km) are also possible. Such scales result from the superposition of the bound long waves and the oscillatory free long wave mode released during the reflection of the wave train. The SR of the total pressure field and the WUR of the radiation stresses are also analyzed. The WGBL solution shows that multiple‐scale modulation of the inviscid region hydrodynamics can be fully transmitted to the Eulerian drift in the viscous region. We also found that under reflective conditions and nearly normal wave incidence, the WUR of the Eulerian drift may present standing modulated patterns with scales of O(100 m), O(1 km), and O(10 km). In the SR, there can be scales of O(100 m) and O(1 km). The mechanisms which determine the vertical structure and direction of the WUR and SR of the Eulerian drift beneath wave groups are also investigated as a function of the main parameters of the WGBL model. Physical implications of and qualifications to the theory presented on nearshore sediment transport are discussed.
Atmospheric forcing on the annual iron cycle in the western Mediterranean Sea: A 1‐year survey
Authors: Bonnet Sophie , Guieu Cécile
Published: September 2006

A 1‐year survey of simultaneous measurements of total atmospheric deposition and dissolved iron concentrations in surface waters (0–40 m) was performed in the northwestern Mediterranean Sea, an area with a marked seasonal hydrological regime. The total atmospheric iron flux was 1118 mg m−2 (i.e., 20.4 mmol m−2). By using aluminium as a crustal marker the deposition was mainly attributed to Saharan dust deposition. Dissolved iron flux was estimated to be 42 μmol m−2 yr−1, of which 44% was anthropogenic in origin and 56% was of Saharan origin. Dissolved iron profiles revealed four typical situations throughout the year: (1) a winter situation with homogenous dissolved iron concentrations ranging from 0.8 to 0.9 nmol L−1, (2) a spring situation with uniformly low concentrations ranging from 0.2 to 0.5 nmol L−1, (3) a summer situation with enriched surface waters up to 1.2 nmol L−1, and (4) an autumnal situation with homogenous concentrations ranging from 0.9 to 1.1 nmol L−1. The results demonstrate that the iron enrichment in the mixed layer observed during the stratified period was of the same order of magnitude as the cumulative atmospheric inputs for the same period. The seasonal variability of dissolved iron (DFe) concentrations in surface waters was driven by a combination of factors, including aeolian Fe deposition, nature of aerosols, vertical mixing, phytoplankton uptake, and particle scavenging. Iron distribution can have a clear biogeochemical effect on the autotrophic communities: The low Fe:P ratio observed during the bloom indicates a possible iron limitation for phytoplankton, and the dissolved iron enrichment during summer is certainly at the origin of the development of diazotrophs populations in the system.
Soil CO2 dynamics and fluxes as affected by tree harvest in an experimental sand ecosystem
Authors: Keller C. K. , White T. M. , O'Brien R. , Smith J. L.
Published: September 2006

Soil CO2 production is a key process in ecosystem C exchange, and global change predictions require understanding of how ecosystem disturbance affects this process. We monitored CO2 levels in soil gas and as bicarbonate in drainage from an experimental red pine ecosystem, for 1 year before and 3 years after its aboveground biomass was removed. Lack of physical disturbance, strict prevention of plant regrowth, and a comparison ecosystem without rooted plants facilitated isolation of the microclimatic and biochemical effects of instantaneous canopy removal and cessation of photosynthesis. Preharvest gas‐phase CO2 levels fluctuated with growing‐season soil temperature but reached their greatest levels (up to 10,000 ppmV) during late winter beneath snow and ice cover. This pattern, and the annual CO2 efflux of ∼500 g C m−2 yr−1, continued for 2 years following harvest; the efflux declined by half in the third year. The surprising continuity of preharvest and postharvest rates of soil CO2 production reflects the replacement of root respiration with microbial respiration of root and litter substrates of declining lability, but boosted by soil temperature increases. Mass balance is consistent with a bulk root+litter exponential decay time (−1/k) of 4–6 years, such that most of the subsurface biomass accumulated over 15 years of tree growth would be lost in a decade after the harvest. The preharvest bicarbonate C efflux, which was less than 0.1% of the gas‐phase efflux, trebled after the harvest owing to elimination of evapotranspiration and consequent increases in drainage while soil CO2 levels remained high. A large fraction of this “hydrospheric” sink for atmospheric CO2 is attributed to weathering under high soil CO2 levels before spring snowmelt and soil‐water flushing. These observations suggest that disturbance may enhance long‐term chemical‐weathering CO2 sinks.
Anomalous early aftershock decay rate of the 2004 Mw6.0 Parkfield, California, earthquake
Authors: Peng Zhigang , Vidale John E. , Houston Heidi
Published: September 2006

We analyze the seismicity rate immediately after the 2004 Mw6.0 Parkfield, California, earthquake from near‐source seismograms. By scrutinizing high‐frequency signals, we can distinguish mainshock coda from early aftershocks occurring as soon as 30 s after the mainshock. We find, as expected, that a significant fraction of aftershocks in the first few hours after the main shock are missing in the Northern California Seismic Network catalog. We observe a steady rate of aftershocks in the first 130 s, followed by a power‐law decay of aftershock activity. Thus, there appears to be a distinct early stage of aftershock activity that does not fit the Omori's law with a constant p value, a phenomenon that we refer to as Early Aftershock Deficiency (EAD). Our observation suggests that mainshock rupture and aftershocks are distinct processes, not described by a single Omori's law. Several physical models of aftershocks can explain the EAD.
A mixed‐phase relative rates technique for measuring aerosol reaction kinetics
Authors: Hearn John D. , Smith Geoffrey D.
Published: September 2006

A mixed‐phase relative rates approach for measuring rates of reaction in aerosols is presented. Using this method the rate of reaction of methyl oleate (MO) particles, normalized to the gas‐particle collision rate, was measured to be γMO = 1.12 (±0.36) × 10−3 with 2‐methyl‐2‐butene as the gas‐phase reference. This value compares favorably with our previously published value of 1.23 × 10−3 measured using an absolute technique. Reaction of bis(2‐ethylhexyl) sebacate (BES) particles with Cl and OH radicals was also studied using acetone and hexanal, respectively, as the gas‐phase references. The rates of reaction of BES, normalized to the gas‐particle collision rate, were measured to be γBES = 1.8 (−0.3+0.8) and γBES = 2.0 (−0.1+0.6) with Cl and OH, respectively. These fast rates of reaction (γBES > 1) imply that secondary reactions, perhaps involving radical chain mechanisms, could impact the rate at which organic particles are oxidized in the atmosphere.
Gas‐phase products and secondary aerosol yields from the photooxidation of 16 different terpenes
Authors: Lee Anita , Goldstein Allen H. , Kroll Jesse H. , Ng Nga L. , Varutbangkul Varuntida , Flagan Richard C. , Seinfeld John H.
Published: September 2006

The photooxidation of isoprene, eight monoterpenes, three oxygenated monoterpenes, and four sesquiterpenes were conducted individually at the Caltech Indoor Chamber Facility under atmospherically relevant HC:NOx ratios to monitor the time evolution and yields of SOA and gas‐phase oxidation products using PTR‐MS. Several oxidation products were calibrated in the PTR‐MS, including formaldehyde, acetaldehyde, formic acid, acetone, acetic acid, nopinone, methacrolein + methyl vinyl ketone; other oxidation products were inferred from known fragmentation patterns, such as pinonaldehyde; and other products were identified according to their mass to charge (m/z) ratio. Numerous unidentified products were formed, and the evolution of first‐ and second‐generation products was clearly observed. SOA yields from the different terpenes ranged from 1 to 68%, and the total gas‐ plus particle‐phase products accounted for ∼50–100% of the reacted carbon. The carbon mass balance was poorest for the sesquiterpenes, suggesting that the observed products were underestimated or that additional products were formed but not detected by PTR‐MS. Several second‐generation products from isoprene photooxidation, including m/z 113, and ions corresponding to glycolaldehyde, hydroxyacetone, methylglyoxal, and hydroxycarbonyls, were detected. The detailed time series and relative yields of identified and unidentified products aid in elucidating reaction pathways and structures for the unidentified products. Many of the unidentified products from these experiments were also observed within and above the canopy of a Ponderosa pine plantation, confirming that many products of terpene oxidation can be detected in ambient air using PTR‐MS, and are indicative of concurrent SOA formation.
Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds
Authors: Keil Adam D. , Shepson Paul B.
Published: September 2006

The concentrations of a suite of halogenated volatile organic compounds (HVOCs) were measured near Barrow, Alaska, from January to April 2005. The HVOCs are produced from the reaction of bromine and chlorine atoms with ethene and propene. During periods of decreasing ozone concentration, increases in the HVOC concentrations allowed for the calculation of the ratio of bromine to chlorine radical concentrations, based on available kinetic data. We use these concentration data to interrogate the chemistry that results in tropospheric ozone depletion in the Arctic, the possible sources of ozone depleting halogen molecules, and the spatial scale in which ozone depletion occurs. We report calculated halogen atom concentration ratios ([Br]/[Cl]) during partial ozone depletion events. The concentration ratio was observed to range from 80 ± 30 to 990 ± 300 when ozone concentrations were above 15 ppb. These data make it clear that chlorine and bromine atom chemistry is active in the Arctic troposphere beginning at twilight, even absent large‐scale ozone depletion, and that the sources of the chlorine atoms are poorly understood.
Exact density functionals for two-electron systems in an external magnetic field
Authors: Zhu Wuming , Trickey S. B.
Published: September 2006

In principle, the extension of density functional theory (DFT) to Coulombic systems in a nonvanishing magnetic field is via current DFT (CDFT). Though CDFT is long established formally, relatively little is known with respect to any generally applicable, reliable approximate EXC and AXC functionals analogous with the workhorse approximate functionals (local density approximation and generalized gradient approximation) of ordinary DFT. Progress can be aided by having benchmark studies on a solvable correlated system. At zero field, the best-known finite system for such purposes is Hooke’s atom. Recently we extended the exact ground state solutions for this two-electron system to certain combinations of nonzero external magnetic fields and confinement strengths. From those exact solutions, as well as high-accuracy numerical results for other field and confinement combinations, we construct the correlated electron density and paramagnetic current density, the exact Kohn-Sham orbitals, and the exact DFT and CDFT exchange-correlation energies and potentials. We compare with results from several widely used approximate functionals, all of which exhibit major qualitative failures, whether in CDFT or in naive application of ordinary DFT. We also illustrate how the CDFT vorticity variable ν is a computationally difficult quantity which may not be appropriate in practice to describe the external B field effects on EXC and AXC.
Coupling between hydration layer dynamics and unfolding kinetics of HP-36
Authors: Bandyopadhyay Sanjoy , Chakraborty Sudip , Bagchi Biman
Published: September 2006

We have performed atomistic molecular dynamics simulations of aqueous solutions of HP-36 at 300K in its native state, as well as at high temperatures to explore the unfolding dynamics of the protein and its correlation with the motion of water around it. On increasing the temperature a partially unfolded molten globule state is formed where the smallest α helix (helix 2) unfolds into a coil. It is observed that the unfolding is initiated around the residue Phe-18 which shows a sharp displacement during unfolding. We have noticed that the unfolding of the protein affects the density of water near the protein surface. Besides, the dynamics of water in the protein hydration layer has been found to be strongly correlated with the time evolution of the unfolding process. We have introduced and calculated a displacement time correlation function to monitor the change in water motion relative to the protein backbone during unfolding. We find that the unfolding of helix 2 is associated with an increase in mobility of water around it as compared to water around the other two helices. We have also explored the microscopic aspects of secondary structure specific and site specific solvation dynamics of the protein. The calculations reveal that unfolding influences the solvation dynamics of the protein molecule in a heterogeneous manner depending on the location of the polar probe residues. This seems to be in agreement with recent experimental findings.
Lattice theory of ultrafast excitonic and charge-transfer dynamics in DNA
Authors: Bittner Eric R.
Published: September 2006

We propose a lattice fermion model suitable for studying the ultrafast photoexcitation dynamics of ordered chains of deoxyribonucleic acid (DNA) polymers. The model includes both parallel (intrachain) and perpendicular (cross-chain) terms as well as diagonal cross-chain terms coupling neighboring bases. The general form of our Hamiltonian is borrowed from lattice fermion models of quantum chromodynamics. The band structure for this model can be determined analytically, and we use this as a basis for computing the singly excited states of the poly(dA)poly(dT) DNA duplex using configuration interaction singles. Parameters for the model are taken from various literature sources and our own ab initio calculations. Results indicate that the excited states consist of a low energy band of dark charge-separated states followed by separate bands of delocalized excitonic states which have weak mixing between the thymidine and adenosine sides of the DNA chain. We then propose a lattice exciton model based upon the transition dipole-dipole couplings between bases and compare the analytical results for the survival probability of an initially localized exciton to exact numerical results. The results herein underscore the competing role of excitonic and charge-transfer dynamics in these systems.
Single-photon pump
Authors: Osborn K. D. , Keller M. W.
Published: September 2006

The authors describe a gated quantum dot device called a single-photon pump that produces single photons on demand through the controlled tunneling of individual electrons and holes. Simulations using an InGaAs∕GaAs dot show that two modes of operation are possible, with one mode particularly attractive for quantum cryptography applications because it cannot produce more than one photon per cycle.
Electric-field-induced fluorescence quenching in dye-doped tris(8-hydroxyquinoline) aluminum layers
Authors: Luo Yichun , Aziz Hany , Popovic Zoran D. , Xu Gu
Published: September 2006

The authors measured electric-field-induced fluorescence quenching (EFIFQ) in both undoped and fluorescent dye-doped tris(8-hydroxyquinoline)aluminum (AlQ3) layers of organic light-emitting devices. Results show that doped AlQ3 layers demonstrate smaller EFIFQ than undoped ones. The phenomenon is attributed to the narrower energy band gap of the guest molecule relative to that of the host material, which makes it less prone to electric-field-induced dissociation of the excited state. Results also show that increasing the concentration of the guest material or decreasing its band gap leads to a decrease in EFIFQ.
A theoretical study of conformational properties of dendritic block copolymers of first generation
Authors: Kosmas M. , Vlahos C. , Avgeropoulos A.
Published: September 2006

Conformational properties of a dendritic block copolymer of the first generation are studied by means of an analytic calculation and dimensionality techniques. The polymer can have different functionalities and branch lengths in the interior region and the exterior shell. Three parameters are included in order to describe the intensity of the interactions between the same or different monomeric units. Based on the average end to end distances of the branches effective angles are defined in order to study how the microscopic parameters control the position and activity of the end groups, but also the hollowness in the internal region and the tweezing ability of the external shell of the macromolecule.
Critical nickel thickness to form silicide transrotational structures on [001] silicon
Authors: Alberti Alessandra , Bongiorno Corrado , Rimini Emanuele , Grimaldi Maria Grazia
Published: September 2006

The effect of the sputtered Ni layer thickness (7–14nm) on the silicide phase transition was studied at 260°C. In 7-nm-thick layers, the complete mixing of Ni and Si occurring during deposition produces stable Ni2Si transrotational structures which further evolve into similar NiSi domains within 50min of annealing. In 14-nm-thick layers, the residual unmixed Ni atoms diffuse towards the interface and speed up the transition from Ni2Si to NiSi (25min) by promoting the nucleation of polycrystaline NiSi grains. A competition between NiSi trans- and poly-structures occurs, and the resulting layer morphology depends on the reaction temperature.
Terahertz radiation generated and detected by Br+-irradiated In0.53Ga0.47As photoconductive antenna excited at 800nm wavelength
Authors: Chimot N. , Mangeney J. , Mounaix P. , Tondusson M. , Blary K. , Lampin J. F.
Published: September 2006

The authors investigate the generation and the detection of terahertz radiation by Br+-irradiated In0.53Ga0.47As photoconductive antennas using an optical excitation at 800nm wavelength. The detected temporal wave form presents a full width at half maximum of 650fs. The signal-to-noise ratio and frequency range of the emitted terahertz radiations are similar to those emitted by low-temperature-grown GaAs photoconductive antennas. The dependences of terahertz wave form amplitude on optical pump power for both Br+-irradiated In0.53Ga0.47As and low-temperature-grown GaAs photoconductive antennas are investigated and compared.
Stable mode locking via ground- or excited-state transitions in a two-section quantum-dot laser
Authors: Cataluna M. A. , Sibbett W. , Livshits D. A. , Weimert J. , Kovsh A. R. , Rafailov E. U.
Published: September 2006

The authors demonstrate stable mode locking that involves transitions within either the ground state (1260nm) or the excited state (1190nm) in a two-section quantum-dot laser, at repetition frequencies of 21 and 20.5GHz, respectively. The average power of the mode-locked output was in excess of 35mW for operation in the ground state and 25mW in the excited state. The selection of pulse generation between these states in the mode-locking regime is controlled by the electrical biasing conditions.
Magnetocaloric effect in Gd-based bulk metallic glasses
Authors: Luo Q. , Zhao D. Q. , Pan M. X. , Wang W. H.
Published: September 2006

Magnetocaloric effect and refrigerant capacity of Gd-based Gd53Al24Co20Zr3 and Gd33Er22Al25Co20 bulk metallic glasses are investigated. It is found that the magnetic entropy changes compare favorably with that of Gd and are slightly larger than that of the known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1. Their good refrigerant efficiency combining with high electrical resistivity, high thermal stability, outstanding mechanical properties, tunable nature, and sufficiently soft magnetic property make them an attractive candidate for magnetic refrigerants in the temperature range of 10–100K.
Time-resolved measurement of capacitance in a Josephson tunnel junction
Authors: Sun Guozhu , Chen Jian , Ji Zhengming , Xu Weiwei , Kang Lin , Wu Peiheng , Dong Ning , Mao Guangfeng , Yu Yang , Xing Dingyu
Published: September 2006

The capacitance of a Josephson tunnel junction is an important parameter, which determines its plasma frequency ωp and thus the energy level spacing in the quantum regime. When a microwave signal at the frequency of ω is applied to a current-biased junction in its zero-voltage state, the escape rate from this state is somehow enhanced. The enhancement is expected to go through a pronounced maximum when ωp=ω. Making use of such microwave generated resonant activation in the thermal regime, we have developed a time-resolved measurement scheme for determining the junction capacitance with an uncertainty of less than 2%.
Planar waveguide-type saturable absorber based on carbon nanotubes
Authors: Kashiwagi Ken , Yamashita Shinji , Nasu Yusuke , Yaguchi Hiroshi , Goh Chee Seong , Set Sze Yun
Published: September 2006

The authors propose and demonstrate a planar waveguide-type optical device based on carbon nanotubes (CNTs). They realize saturable absorbers utilizing the interaction between the evanescent field of guiding mode and the CNTs. Saturable absorption characteristics are observed and insertion loss decreases ∼3% by high power pulsed laser. The device shows that polarization dependence originated from the asymmetric structure of their device and over 15dB polarization dependent loss. The saturable absorption is observed only in the polarization state that shows a maximum loss caused by the CNTs.
Greatly improved performance of 340nm light emitting diodes using a very thin GaN interlayer on a high temperature AlN buffer layer
Authors: Wang T. , Lee K. B. , Bai J. , Parbrook P. J. , Airey R. J. , Wang Q. , Hill G. , Ranalli F. , Cullis A. G.
Published: September 2006

This letter reports a simple approach to significantly improve the performance of 340nm ultraviolet light emitting diodes (UV-LEDs) on an AlN buffer layer. Greatly improved optical and electrical properties of the 340nm UV-LED have been achieved by using a very thin GaN interlayer (10–20nm), deposited on AlN as a buffer layer directly on sapphire prior to growth of the UV-LED structure. Compared with the UV-LED without the thin GaN interlayer, the output power of the LED with it is increased by a factor of ∼2.2, and the applied bias voltage at 20mA drops from 6.5to∼5V. High resolution transmission electron observation indicates that the thin GaN interlayer can effectively stop the penetration of the dislocations in the AlN buffer layer into the overlaying AlGaN layer, while most of the dislocations in the AlN buffer layer in the UV-LED without the thin GaN interlayer can propagate into the overlying AlGaN layer. Therefore, the enhanced performance of the 340nm UV-LEDs results from a massive reduction in dislocation density in the overlying device structure due to the very thin GaN interlayer. Since it is extremely difficult to reduce the dislocation density in an AlN layer on sapphire, the simple and reliable approach reported in this letter provides a good alternative option to prevent the propagation of dislocations from an AlN buffer into an overlying device structure.
Punchthrough effects on the electrostatic discharge robustness of ultrathin silicon films on insulator devices
Authors: Lee Jam-Wem , Tang Howard
Published: September 2006

Physical mechanisms that dominate the electrostatic discharge (ESD) robustness of silicon-on-insulator (SOI) devices are theoretically and experimentally investigated here. The authors experimentally find that the ESD robustness depends strongly on the device geometry correlated turn on mechanism. Moreover, the punchthrough mechanism is theoretically demonstrated to be the unsuitable turn on mechanism that causes a nonuniform current distribution and a low ESD strength. The punchthrough mechanism, according to their theoretical analysis, will occur in scaled down structure and reduce the benefits arising from sizing down. Therefore, optimization of a device structure is necessary to prevent nanoscaled SOI devices from the punchthrough induced ESD robustness degradation.
Highly efficient and color-tuning electrophosphorescent devices based on CuI complex
Authors: Che Guangbo , Su Zisheng , Li Wenlian , Chu Bei , Li Mingtao , Hu Zhizhi , Zhang Zhiqiang
Published: September 2006

Highly efficient electrophosphorescence from organic light-emitting devices based on a CuI complex, [Cu(DPEphos)(Dicnq)]BF4 (DPEphos=bis[2-(diphenylphosphino)phenyl]ether and Dicnq=6,7-Dicyanodipyrido[2,2-d:2′,3′-f] quinoxaline), doped into 4,4′-N,N′-dicarbazole-biphenyl is demonstrated. The performances of these devices fabricated by vacuum vapor deposition technique are among the best reported for devices incorporating CuI complexes as emitters. A low turn-on voltage of 4V, a maximum current efficiency up to 11.3cd∕A, and a peak brightness of 2322cd∕m2 were achieved, respectively. The phosphorescent operating mechanism of organic light-emitting devices based on CuI complex was discussed. Electroluminescent colors can be tuned ranging from green-yellow to orange-red region, and its band tail at longer wavelength can cover near infrared.
Theory of relaxation oscillations in semiconductor quantum dot lasers
Authors: Malić Ermin , Ahn Kwang J. , Bormann Moritz J. P. , Hövel Philipp , Schöll Eckehard , Knorr Andreas , Kuntz Matthias , Bimberg Dieter
Published: September 2006

A microscopic approach combining rate equations for photon and electron/hole occupations with kinetic equations for Coulomb scattering rates involving quantum dot and wetting layer states in InAs∕GaAs quantum dot lasers is presented. The authors find strong damping of relaxation oscillations on a picosecond to nanosecond time scale depending on the type of the initial perturbation, similar to the damping observed in experiments by various groups. They show that the Coulomb interaction is crucial for an understanding of this characteristic strong damping.
Structure change of liquid GaSb under pressure: An ab initio molecular-dynamics simulation
Authors: Gu Tingkun , Qin Jingyu , Bian Xiufang , Xu Changye
Published: September 2006

We have performed ab initio molecular-dynamics simulation of liquid GaSb (l-GaSb) up to 20.0GPa. The calculated structure factors are consistent with the recent experimental results, and the partial structure parameters show that the structure of l-GaSb under pressure contracts nonuniformly. In the whole calculated pressure region, the contraction of l-GaSb can be divided into three substages: 1.8–5.4, 5.4–10.0, and 10.0–20.0GPa. It is further confirmed by analyzing the bond-angle distributions of Ga–Ga–Ga and Sb–Sb–Sb that the rearrangement of Sb atoms under pressure plays a crucial role in the structure change of l-GaSb.
InGaN quantum wells with small potential fluctuation grown on InGaN underlying layers
Authors: Akasaka Tetsuya , Gotoh Hideki , Kobayashi Yasuyuki , Nakano Hidetoshi , Makimoto Toshiki
Published: September 2006

A series of InGaN quantum wells (QWs) emitting blue-green, blue, violet, or ultraviolet light was grown on InGaN underlying layers (ULs). The potential fluctuation in these InGaN QWs was carefully measured using time-resolved photoluminescence, taking several steps to reduce the quantum confinement Stark effect. The potential fluctuation of InGaN QWs on InGaN ULs was smaller than that on conventional GaN ULs with the identical emission wavelength. A violet-light-emitting diode using an InGaN UL had the electroluminescence intensity approximately five times higher than the one using a conventional GaN UL under the low injection-current conditions, indicating that an InGaN UL effectively eliminates the nonradiative recombination centers in the InGaN QWs.
Effect of space charge polarization in radio frequency microelectromechanical system capacitive switch dielectric charging
Authors: Papaioannou G. J. , Exarchos M. , Theonas V. , Psychias J. , Konstantinidis G. , Vasilache D. , Muller A. , Neculoiu D.
Published: September 2006

The letter presents the investigation of the temperature dependence of the charging mechanism of dielectric layer in radio frequency microelectromechanical system switch. The accumulated charge kinetics are monitored through the transient response of device capacitance when a bias greater than pull-in is applied. The capacitance transient response is shown to follow a stretched exponential law. The “time scale” of the stretched exponential process is found to be thermally activated, with an activation energy that is determined from Arrhenius plot.