bluuebunny/crossref_metadata_2025_split huggingface dataset:
20 GHz gated tunnel diode based UWB pulse generator
Authors: Egard Mikael , Ärlelid Mats , Lind Erik , Astromskas Gvidas , Wernersson Lars‐Erik 
Published: March 2009

AbstractWe demonstrate a pulse generator based on a GaAs‐AlGaAs gated resonant tunneling diode (RTD). This is realized by integrating a third terminal, the gate, into the current path of a RTD. The gate consists of a 200 Å thick tungsten grating buried 300 Å above the RTD. This implementation allows for control of the current through the RTD. By integrating this device in parallel with an on‐chip inductance, a negative differential resistance (NDR) oscillator is formed. It is demonstrated that by using the gate to change the output conductance of the device, the oscillations may be switched on and off, creating short bursts of RF power. This technique allows for rapid quenching of the oscillator, and hence the ability to generate short pulses at high frequency, enabling impulse radio ultra‐wideband communication implementations. The highest demonstrated oscillation frequency is 22 GHz with an output power of –4.1 dBm, and the shortest pulses generated are 1.3 ns. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deterministic self‐organization: Ordered positioning of InAs quantum dots by self‐organized anisotropic strain engineering on patterned GaAs (311)B
Authors: Selçuk E. , Hamhuis G. J. , Nötzel R. 
Published: March 2009

AbstractLaterally ordered InGaAs quantum dot (QD) arrays, InAs QD molecules, and single InAs QDs in a spot‐like periodic arrangement are created by self‐organized anisotropic strain engineering of InGaAs/GaAs superlattice (SL) templates on planar GaAs (311)B substrates in molecular beam epitaxy. On shallow‐ and deep‐patterned substrates the respectively generated steps and facets guide the self‐organization process during SL template formation to create more complex ordering such as periodic stripes, depending on pattern design. Here we demonstrate for patterns such as shallow‐ and deepetched round holes and deep‐etched zigzag mesas that the self‐organized periodic arrangement of QD molecules and single QDs is spatially locked to the pattern sidewalls and corners. This extends the concept of guided self‐organization to deterministic self‐organization. Absolute position control of the QDs is achieved without one‐to‐one pattern definition. This guarantees the excellent arrangement control of the ordered QD molecules and single QDs with strong photoluminescence emission up to room temperature, which is required for future quantum functional devices. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale modeling and simulation of silicon carbide oxidation
Authors: Chatterjee A. N. , Matocha K. S. 
Published: March 2009

AbstractThe objective of this theoretical work is to understand the process of thermal oxidation of SiC and investigate the phenomenon of transition layer generation at the SiC/SiO2 interface. We have identified the reaction process to be the rate‐limiting step of SiC oxidation. The dependence of transition layer on temperature and SiC crystal plane orientation has been studied. The difference in the oxidation rates of Si face and C face of SiC has been explained using the proposed multiscale approach. The computed concentration of carbon cluster at the interface indicates the presence of interface traps due to incomplete oxidation of SiC. The mathematical models and simulation results have been validated with experimental correlations. The proposed model is valid within typical temperature conditions of dry oxidation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Perturbing GaN/AlN quantum dots with uniaxial stressors
Authors: Moshe Ofer , Rich Daniel H. , Damilano Benjamin , Massies Jean 
Published: March 2009

AbstractWe have studied the effect of uniaxial stress on the optical polarization properties of GaN/AlN quantum dots (QDs) grown on Si(111) substrates. Microcracks form as a result of the thermal expansion coefficient mismatch between the GaN/AlN layers and the Si(111) substrate. We show that such microcracks serve as excellent stressors through which the strain tensor of the GaN/AlN QDs can be modified for studies of strain‐induced changes in the optical properties using a spatially and temporally resolved probe, such as with cathodoluminescence (CL) imaging and spectroscopy. CL measurements of the ground‐state excitonic transition of vertically stacked GaN/AlN quantum dots (QDs) exhibit an in‐plane linear polarization anisotropy in close proximity to microcracks, consistent with the presence of uniaxial stress. The spatial dependence of the polarization anisotropy and CL decay time in varying proximity to the microcracks are studied as a function of temperature in order to assess the influence of thermal stress variations on the oscillator strength between electrons and holes. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum‐corrected Monte Carlo study of quasi‐ballistic transport in nano‐scale InGaAs HEMTs
Authors: Yamada Ryohei , Takegishi Takayuki , Hirata Yuko , Matsumoto Takayuki , Hara Shinsuke , Fujishiro Hiroki I. 
Published: March 2009

AbstractThe electron transport phenomena in InGaAs HEMTs at low Vgs condition are shown to be similar to Si MOSFETs. At the potential bottleneck under the gate, the momentum distribution function of the electron, f (x, kx), becomes an asymmetric shape with a small tail spread in negative direction. As Lg decreases, the negative tail of f (x, kx) becomes less significant, which is responsible for the increase of the electron velocity at the bottleneck, vs. We demonstrate that the electron scatterings collapse the hemispherical shape of f (x, kx) at the bottleneck. As Lg decreases, vs approaches the ballistic value. The ballisticity is estimated on the basis of the quasi‐ballistic transport theory. The backscattering coefficient, R, decreases and the index of the ballisticity, rB, increases as Lg decreases. At Lg = 10 nm, R and rB are estimated to be about 0.05 and 0.97, respectively, which indicates that at Lg = 10 nm, vs is almost reaching the ballistic limit. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of captive adolescent male chimpanzees on wounding: management and welfare implications
Authors: Ross S. R. , Bloomsmith M. A. , Bettinger T. L. , Wagner K. E. 
Published: March 2009

AbstractAdolescence, the period lasting from the onset of puberty to the emergence of physical and sexual maturity, is a period of social change for many species including chimpanzees. Several reports have implicitly linked the physiological changes that occur during male chimpanzee adolescence to significant disruption in the social group, which in turn may result in serious agonism and wounding. To assess the association between adolescent males and wounding rates, 38 institutions housing 399 chimpanzees among 59 social groups, recorded all wounds incurred by chimpanzees over a 6‐month period. The rate of wounding did not differ between groups with or without adolescent males. Adolescent males received the most wounds, but were no more likely to cause wounds than group members of any other sex–age class. Social groups with multiple adult males experienced lower wounding rates than those with a single adult male. Results indicate that (1) adolescent male chimpanzees may receive, but not inflict, more wounds than chimpanzees in other sex–age classes; and (2) management strategies that support natural social groupings may control and limit group agonism. Zoo Biol 28:623–634, 2009. © 2009 Wiley‐Liss, Inc.
Direct medical mental health care costs of schizophrenia in France, Germany and the United Kingdom – Findings from the European Schizophrenia Cohort (EuroSC)
Authors: Heider Dirk , Bernert Sebastian , König Hans-Helmut , Matschinger Herbert , Hogh Theresa , Brugha Traolach S. , Bebbington Paul E. , Azorin Michel , Angermeyer Matthias C. , Toumi Mondher 
Published: March 2009

AbstractObjectivesTo quantify and compare the resource consumption and direct costs of medical mental health care of patients suffering from schizophrenia in France, Germany and the United Kingdom.MethodsIn the European Cohort Study of Schizophrenia, a naturalistic two-year follow-up study, patients were recruited in France (N = 288), Germany (N = 618), and the United Kingdom (N = 302). Data about the use of services and medication were collected. Unit cost data were obtained and transformed into United States Dollar Purchasing Power Parities (USD-PPP). Mean service use and costs were estimated using between-effects regression models.ResultsIn the French/German/UK sample estimated means for a six-month period were respectively 5.7, 7.5 and 6.4 inpatient days, and 11.0, 1.3, and 0.7 day-clinic days. After controlling for age, sex, number of former hospitalizations and psychopathology (CGI score), mean costs were 3700/2815/3352 USD-PPP.ConclusionsService use and estimated costs varied considerably between countries. The greatest differences were related to day-clinic use. The use of services was not consistently higher in one country than in the others. Estimated costs did not necessarily reflect the quantity of service use, since unit costs for individual types of service varied considerably between countries.
Soil Analysis as a guide to the Manurial Treatment of Poor Pastures
Authors: Wood T. B. , Berry R. A. 
Published: March 2009

Summarising the above comparisons between soil analyses and results of manuring, the following conclusions are arrived at:That except in extreme cases the determination of the percentages of “total” nitrogen, phosphoric acid, potash, and lime, in a soil does not give reliable indications as to the possibility of improving the pasture by manuring.That determination of the percentage of phosphoric acid soluble in 1 per cent, citric acid solution does generally give reliable indications as to the probable success of phosphatic manuring, provided that for pasture soils the limit below which “available“ phosphoric acid may be considered as deficient is fixed as high as 0·02 per cent.That potash manuring is suggested as likely to give distinct results if the soil contains not more than 0·01 per cent, of potash soluble in 1 per cent, citric acid solution.That liming is not indicated as likely to be profitable unless the soil contains certainly less than 0·25 per cent, of chalk.
Note on the Composition of Gas Lime
Authors: Bhatt P. J. 
Published: March 2009

Very few analyses of gas lime have been published; consequently the following analyses made in the laboratory of the Department of Agriculture of the University of Cambridge may be of interest to readers of this Journal.The samples of gas lime were obtained from the Cambridge Gas Works. One was what is known as carbonated lime, that is to say, lime which had been used for purifying the gas after it had previously been purified by hydrated ferric oxide. This sample, as shown by the analysis, is practically moist calcium carbonate. It was obtained in a perfectly fresh condition. The second sample was described by the Works Manager as “sulphided lime.” It had been used for purifying gas without the previous use of ferric hydrate. A sample was taken from the centre of a large heap which had been standing for about a year.
Estimation of Calcium Carbonate in Soils
Authors: Marr F. S. 
Published: March 2009

Boiling acid at atmospheric pressure decomposes organic matter in soil with evolution of carbon dioxide, and thus renders the results obtained for carbonate too high. Where there is a fairly large percentage of carbonate, the error introduced in this way is of no great importance, but in soils containing less than 1% of calcium carbonate and especially in acid soils, the error introduced by thus boiling with acid may be very considerable.The weaker the acid used the better so long as there is fair excess. The writer recommends for acid soils and those containing low percentages of carbonate (as can be seen by making a rough preliminary test), 2 c.c. of strong hydrochloric acid and about 100 c.c. of water: 20 grams of soil should be used when the amount of carbonate is small. The acid may be conveniently added by making up a solution containing 100 c.c. of strong hydrochloric acid per litre, and introducing 20 c.c. of this solution along with 80 c.c. of water. For most soils, 5 c.c. of strong hydrochloric acid to 100 c.c. of water will be found convenient.If possible distillation under reduced pressure should be used, as under this condition practically no decomposition of organic matter takes place, while carbonate is readily decomposed: the distillation should be continued for twenty minutes at a temperature of about 50° C.
On Ovariotomy in Sows; with Observations on the Mammary Glands and Internal Genital Organs
Authors: Mackenzie K. J. J. , Marshall F. H. A. 
Published: March 2009

Black pigment is very frequently, but not invariably present in the mammary tissue of Large-Black, Berkshire and other dark-coloured sows. It is stated that the presence of this pigment (apart altogether from the question of the pigs being “on heat”) renders the bacon less saleable, owing to its discoloured or “seedy” appearance. If this is the case, it ought to be possible to remedy this fault, by breeding from individuals in which this pigment is absent, and so building up a strain of increased commercial value.If on the other hand it be the case that the presence of black pigment is not in itself objectionable, but that the changes in the mammary area due to the occurrence of heat are what are not desired, the remedy is to be sought in spaying, a practice which must be carried out on a sufficient scale and be efficiently performed. That imperfect spaying (in which one, or a part of one, ovary is left behind, while the bed is wholly or partly removed) sometimes happens is shown by the facts described in this paper.The expenses of the investigation described in this paper have been very largely defrayed by a grant made by the Development Commissioners through the Board of Agriculture and Fisheries.
Lime-Sulphur Sprays, their Composition and Analysis
Authors: Ramsay A. A. 
Published: March 2009

In a previous paper I have stated: “The monosulphide sulphur, therefore, appears to be essentially calcium hydroxyhydrosulphide CaHSOH with very minute quantities of calcium hydrosulphide CaH2S2. The solution of lime sulphur then appears to consist of calcium hydroxy-hydrosulphide, calcium thiosulphate, calcium sulphate with sulphur held in solution.”I have now to amend this by adding “calcium disulphide” to the above.The method of analysis is now as follows: Preparation of sample. 50 c.c. of the concentrated lime sulphur to be diluted to 500 c.c. with water.
The celery-rot bacillus
Authors: Wormald H. 
Published: March 2009

1. A bacillus isolated from celery affected by soft-rot reproduced the disease when inoculated into celery plants.2. Other vegetables commonly grown as garden crops are susceptible to attack by the same organism.3. The bacillus is very sensitive to the action of antiseptic and germicidal reagents.4. It is typically bacilliform but under certain conditions may be almost isodiametric and coccus-like, or it may develop into very long filaments.5. It is capable of growing in a synthetic medium containing a sugar or pectin as the sole carbon compound.6. Its group number is 221·1113522 and since B. carotovorus Jones proves to be a yellow organism the latter must also be included under that number. The two organisms appear to differ slightly on minor points, e.g. vigour of growth in Uschinsk's solution and on celery extract agar.7. Like B. carotovorus the celery-rot organism is very sensitive to desiccation.
The electrical conductivity of extracts from soils of various types, and its use in detecting infertility
Authors: Atkins W. R. G. 
Published: March 2009

1. The electrical conductivity of aqueous extracts of soils, in the proportion of one of soil to five of water, varies according to the time of extraction. In the more fertile soils extraction for three to four hours gives less than half as great a conductivity as is given in 4 to 11 days.2. In peat the maximum value is reached almost at once, the extract having a high conductivity. The maximum value is also reached quickly in certain infertile soils, which give an extract of very low conductivity, closely similar to that of the purest upland streams.3. A high electrical conductivity in the extract may only indicate the presence of an excess of salts, and does not necessarily indicate a good soil. It seems, however, that a rapid increase in conductivity as extraction is prolonged indicates increased solubility, partly through bacterial action and may be considered as a useful indication of fertility. A low conductivity, which remains low on continued extraction, denotes a soil so insoluble as to be unfertile.
Maize silage. I
Authors: Woodman Herbert Ernest , Amos Arthur 
Published: March 2009

It has been shown that maize silage of good quality can be produced with losses of dry matter which are not necessarily much greater than those which characterise the production of oat and tare silage.Excessive drainage of juice consequent on immaturity of crop contributes materially to the total loss of dry matter.The main reason for the comparative failure of attempts in this country to produce maize silage successfully from the points of view of quality and economy lies probably in the general use of the late maturing variety, American Horse Tooth. Success will probably depend on growing a variety of maize which is able to reach a desirable stage of maturity under English conditions before being cut for the silo. Preliminary trials have indicated that the necessary qualities may be found in certain varieties like Saltzer's North Dakota, Longfellow, Compton's Early and White Cap, all of which mature at least a month before American Horse Tooth.
Studies in crop variation. I. An examination of the yield of dressed grain from Broadbalk
Authors: Fisher R. A. 
Published: March 2009

In Part I is given a survey of the results of a statistical examination of the yield of the plots of Broadbalk “Wheat field during 67 years. The main features of the comparison of mean yields are well known; the comparative rates of decrement, shown in Section 5, supply a class of facts well worthy of further study. Particularly striking are the relatively slow rates of decrement of plots 2b and 8, compared with plot 7, which would seem to show a permanent advantage in very high nitrogenous dressings, and to emphasise the need for caution in the application of the principle of diminishing returns. The evidence of the influence of potassium sulphate and its substitutes, sodium sulphate and magnesium sulphate, shown in Table V, is also very striking. An unsuspected feature of the changes of mean yields, which precludes the possibility of obtaining from these data true curves of exhaustion has appeared in the slow changes which have taken place in all the plots in a similar manner. In Part II the mathematical methods by which the variation has been analysed has been discussed, partly as a justification of novel procedure, partly, to make clear that the three types of variations found have been genuinely distinguished. In Part III such evidence as is available has been presented, in order to throw light upon the possibility that the changes in mean yield have been caused by variations in the prevalence of weeds at different periods.One point of importance which should be emphasised is that average wheat yields, even over long periods, from different fields or for different seasons cannot approach in accuracy the comparison of plots of the same field in the same seasons. The advantage of the method adopted by Lawes in the permanent experiments which he instituted is very evident. The effects of weather clearly require that the seasons should be identical, unless the series be very long, but the slow changes in mean yield show that even comparatively long series of different years from the same field cannot be accurately compared. Within the same field, however, the slow changes have almost proportional effects, and comparison between the mean yields of neighbouring plots may be made with great accuracy. The only case in which changes in mean yield sensibly affect the comparison of averages is that of plots 17 and 18. In comparing these with plots 3 and 4, 5, 7, and 10, it would be more accurate to confine attention to high yielding periods, at which the disturbing causes are at their minimum.It is believed that the deviations from the smooth curves, which have been freed, for the most part, from the effects of exhaustion and weeds, form statistically homogeneous material for the study of meteorological effects.
The effect of basic slag upon grassland, and upon the corn crops obtained when that grassland is ploughed up
Authors: Oldershaw A. W. 
Published: March 2009

In the year 1904, a grass field at Saxmundham Experiment Station was taken in hand by East Suffolk County Council. At that time the herbage in the field was very poor and consisted chiefly of weeds—largely Wild Carrot.The soil is a typical chalky boulder clay of a poor type very stiff to work, but capable of producing good crops of wheat and beans when well drained.
The determination of clay in heavy soils
Authors: Joseph A. F. , Martin F. J. 
Published: March 2009

1. The Sudan method for clay determination worked out by Dr Beam in 1911 has been critically examined and compared with the methods in general use in England and America.2. The essential points of the method lie in (a) the use of sodium carbonate instead of ammonia as the deflocculating agent, and (b) the use of a camel-hair brush for puddling the clay. It differs from the English (and resembles the American) method in that no preliminary acid treatment is used, the height of the sedimentation column is 10 cms. and the time of subsidence 8 hours.3. It can be applied to a sedimentation or centrifugal process: the results agree well with each other and with those obtained by the American method.4. When modified by inclusion of acid treatment, by increasing the time of sedimentation from 8 to 24 hours and reducing the height of the column to 8·6 cms., the results agree well with those obtained by the English method.5. Treatment with acid either in the preliminary operations or for deflocculating clay suspensions may lead to uncertainty in the results in some cases as it causes loss of “clay” by solution.6. The Sudan sedimentation method can be carried out in about one-eighth the time required for the English method, and the centrifugal in about one-third the time required for the American. For general use the sedimentation method is preferred as requiring less attention.
Composition and variation of the milk of Egyptian sheep
Authors: El-Sokkary A. M. , Sirry I. , Hassan H. A. 
Published: March 2009

In this study samples of the mixed milk from a herd of sheep were taken weekly for analysis throughout a season of approximately 7 months. The following are the mean values obtained: sp.gr. 1·0350, S.e.m. 0·0002; acidity 0·226%, S.e.m. 0·003; fat 8·00%, S.e.m. 0·07; S.n.f. 11·35%, S.e.m. 0·06; and total N 0·920%, S.e.m. 0·007.Samples were also taken at 2-week intervals throughout the lactation period of six individual ewes of the Rahmany breed and of the same number of the Awsemy breed. The variation in the composition of their milk throughout lactation and also the variation due to individuality are discussed.