bluuebunny/crossref_metadata_2025 huggingface dataset:
A symbolic approach to polyhedral scene analysis by parametric calotte propagation
Authors: Li Hongbo , Zhao Lina , Chen Ying
Published: December 2007

Polyhedral scene analysis studies whether a 2D line drawing of a 3D polyhedron is realizable in space, and if so, it gives the results of parameterizing the space of all possible realizations. For generic 2D data, symbolic computation with Grassmann–Cayley algebra is needed in the analysis. In this paper, we propose a method called parametric calotte propagation to solve the realization and parameterization problems for general polyhedral scenes at the same time. In algebraic manipulation, parametric propagation is more efficient than elimination. In applications, it can lead to linear construction sequences for nonspherical polyhedra whose resolvable sequences do not exist.
The relationship between geographical information in the Old English Orosius and Latin texts other than Orosius
Authors: Bately Janet M.
Published: December 2007

A great deal has been written about the geographical first chapter of the Old English Orosius since it attracted the attention of scholars in the sixteenth century. Not only has this chapter been a valuable source of information for historians and historical geographers, but also it has proved a fertile subject for speculation, particularly as regards the origins and accuracy of the modifications made in it to its Latin original. Most discussions have been concerned exclusively with the apparently independent section on the geography ofGermania. Recently, however, a theory has gained favour which requires all the ‘new’ geographical information in this work to be taken into consideration: the theory that, to help him in his translation and adaptation, the author may have used amappa mundi, a traditional map portraying theorbis terrarumof classical geographers. Thus Professor Labuda considers the source of certain additional details, such as the association of the Sabaei with Arabia Eudaemon and the location of the legendary Land of Women and Riphaean mountains north of the ninth-century Croats of Bohemia, to be amappa mundion which the author marked the positions of Germanic, Slav and Baltic countries. Dr Havlík and Professor Derolez suggest that the apparent clockwise deviation of a number of directions in Or. may similarly be due to the use of an enlargedmappa mundi. According to them, the author of Or. would seem to have described the relative positions of peoples and countries from the standpoint not of astrological north, south, east and west, but of cartographicoriens(near the mouth of the Ganges),meridies(south of the Nile),occidens(near the Pillars of Hercules) andseptentrio(in the region of the river Tanais). Thus, for instance, the Abodriti, whose ‘centre’, Mecklenburg, was true north-east of the Old Saxons, are cartographic north of them, by virtue of their location on an imaginary line between Saxonia andseptentrio. Finally, Dr Linderski, on the basis of possible classical sources that he has found for Or.'s siting of Dacia east of the Vistula and placing of an unnamed waste-land between Carentania and Bulgaria, has suggested that if the author did indeed use such a map – an alternative being a ‘description’ – it was almost certainly a late offspring of theCommentariiof Agrippa and his now lostmappa mundi.
Land, family and the transmission of property in a rural society of South Bohemia, 1651–1840
Authors: ZEITLHOFER HERMANN
Published: December 2007

This article deals with the changing patterns of transmission of land and houses in pre-industrial rural Bohemia. By linking different sources, such as land registers, census-like lists and a family reconstitution, this study focuses on both the demographic and the economic factors that influenced peasant transmission strategies as well as on the consequences of changing transmission patterns for access to land-ownership in the local society. The results of this study show that patterns of land transmission changed profoundly after about 1720. Between 1651 and 1720 many houses with or without land were sold to non-kin as well as to kin although in both cases a customary and not a market price was paid. Imperfect market mechanisms are also indicated by the frequency of exchanges of houses between families. After around 1720 transmissions of property from father to son progressively became the dominant pattern. The chances of women (both widows and daughters and their husbands) to become property-holders diminished and it became extremely difficult for persons not born into house-owning families to acquire any houses or land.
Remarriage in a stem family system in early modern Japan
Authors: KUROSU SATOMI
Published: December 2007

Drawing data from the local population registers in two northeastern Japanese agricultural villages in the period 1716–1870, this study examines the patterns and covariates of remarriage in a rural community with strong adherence to a stem family organization. Event history analysis is applied separately for males and females, and for two types of previous marriage (uxorilocal and virilocal). Controlling for demographic and economic factors, coresiding parents and children had differential impacts on remarriage for these subgroups. Men and women were tightly bound to the fates of their natal and marital households within the larger context of local economic conditions.
Remarriage, gender and social class: a longitudinal study of remarriage in southern Sweden, 1766–1894
Authors: LUNDH CHRISTER
Published: December 2007

Remarriage was common in Sweden in pre-industrial times, especially among men, although over the nineteenth century the number of remarriages declined. This article analyses remarriages in southern Sweden between 1766 and 1894. Data are derived from family reconstitutions in five rural parishes in southern Sweden, which makes it possible to follow individual widows and widowers from the year of the death of the spouse. The focus here is on the influence of individual characteristics, household composition, food prices and time period on an individual widow's or widower's probability of remarriage. For some variables the effect was quite general, for example the negative effect on remarriage of the individual's age and the decrease in the likelihood of remarriage in the nineteenth century. The influence of other variables was not this straightforward. Socioeconomic status interacted with all variables, especially gender, food prices and the presence of minor or adult children in the household.
Rural land and credit markets, the permanent income hypothesis and proto-industry: evidence from early modern Zurich
Authors: PFISTER ULRICH
Published: December 2007

The study documents fluctuations of proto-industrial income, of occupation, debt and presence on land markets across the life course for rural households in a major proto-industrial region during the seventeenth and eighteenth centuries. These fluctuations are interpreted on the basis that a major objective of households is to equalize their income across different stages of their development. The permanent income hypothesis is then extended to take into account land purchases and debt-contracting that result from the need to adjust land and capital to fluctuations in the size of the family labour force across the family cycle and from endeavours to improve the family's welfare by increasing the labour to land ratio. The empirical material presented shows marked fluctuations of income from proto-industrial work across the life course and suggests the existence of permanent income-cum-accumulation strategies to cope with these fluctuations.
On factorials which are products of factorials
Authors: LUCA FLORIAN
Published: December 2007

In this paper, we look at the Diophantine equation
(0.1)
Under the ABC conjecture, we show that it has only finitely many nontrivial solutions. Unconditionally, we show that the set of n for which the above equation admits an integer solution a1,. . .,at is of asymptotic density zero.
On motivic principal value integrals
Authors: VEYS WILLEM
Published: December 2007

Inspired byp-adic (and real) principal value integrals, we introduce motivic principal value integrals associated to multi-valued rational differential forms on smooth algebraic varieties. We investigate the natural question whether (for complete varieties) this notion is a birational invariant. The answer seems to be related to the dichotomy of the Minimal Model Program.
Geometric collections and Castelnuovo–Mumford regularity
Authors: COSTA L. , MIRÓ–ROIG R. M.
Published: December 2007

The paper begins by overviewing the basic facts on geometric exceptional collections. Then we derive, for any coherent sheaf $\cF$ on a smooth projective variety with a geometric collection, two spectral sequences: the first one abuts to $\cF$ and the second one to its cohomology. The main goal of the paper is to generalize Castelnuovo–Mumford regularity for coherent sheaves on projective spaces to coherent sheaves on smooth projective varieties X with a geometric collection σ. We define the notion of regularity of a coherent sheaf $\cF$ on X with respect to σ. We show that the basic formal properties of the Castelnuovo–Mumford regularity of coherent sheaves over projective spaces continue to hold in this new setting and we show that in case of coherent sheaves on $\PP^n$ and for a suitable geometric collection of coherent sheaves on $\PP^n$ both notions of regularity coincide. Finally, we carefully study the regularity of coherent sheaves on a smooth quadric hypersurface $Q_n \subset \PP^{n+1}$ (n odd) with respect to a suitable geometric collection and we compare it with the Castelnuovo–Mumford regularity of their extension by zero in $\PP^{n+1}$.
Stable sandwich classification theorem for classical-like groups
Authors: ZHANG ZUHONG
Published: December 2007

Let H denote a subgroup of the unitary group U(R, Λ) which is normalized by EU(J, ΓJ) for some form ideal (J, ΓJ) of a commutative form ring (R, Λ). We prove that H satisfies a “sandwich” property, i.e., there exists a form ideal (I ΓI) such that

for some form ideal (I : J7, Ω). This answers a conjecture of Bak (1967) in the stable case.
Sectorial forms and unbounded subnormals
Authors: ATHAVALE AMEER , CHAVAN SAMEER
Published: December 2007

We use the theory of sectorial sesquilinear forms to characterize the closure of the Creation Operator of Quantum Mechanics in the classical set-up. Further, we bring that theory to bear upon the class of unbounded cyclic subnormal operators that admit analytic models; in particular, we provide a sufficient condition for the existence of complete sets of eigenvectors for certain sectorial operators related to unbounded subnormals. The relevant theory is illustrated in the context of a class of analytic models of which the classical Segal–Bargmann space is a prototype. The framework of sectorial sesquilinear forms is also shown to be specially useful for treating questions related to the existence, uniqueness and stability of certain parabolic evolution equations naturally associated with such analytic models.
The second Johnson homomorphism and the second rational cohomology of the Johnson kernel
Authors: SAKASAI TAKUYA
Published: December 2007

The Johnson kernel is the subgroup of the mapping class group of a surface generated by Dehn twists along bounding simple closed curves, and has the second Johnson homomorphism as a free abelian quotient. In terms of the representation theory of the symplectic group, we give a complete description of cup products of two classes in the first rational cohomology of the Johnson kernel obtained by the rational dual of the second Johnson homomorphism.
On decomposition numbers and Alvis–Curtis duality
Authors: ACKERMANN BERND , SCHROLL SIBYLLE
Published: December 2007

We show that for general linear groups GLn(q) as well as for q-Schur algebras the knowledge of the modular Alvis–Curtis duality over fields of characteristic ℓ, ℓ ∤ q, is equivalent to the knowledge of the decomposition numbers.
Temporal adverbs in Icelandic: adverbs of quantification vs. frequency adverbs
Authors: Jóhannsdóttir Kristín M.
Published: December 2007

Temporal adverbs can usually be divided into groups. Amongst those are adverbs of quantification, such as often, sometimes and never, and frequency adverbs, such as constantly and regularly. This paper presents some new data that shows that the Icelandic temporal adverb alltaf ‘always’ can be both an adverb of quantification and a frequency adverb. When alltaf modifies a progressive construction its meaning shifts, depending on the aktionsart of the restrictor. When the restrictor is punctual, alltaf functions as an adverb of quantification and has a frequency meaning (X is always happening at the time Y takes place). When the restrictor is durative, alltaf does not quantify over the event, and instead gets a durative meaning, similar to that of stöðugt ‘constantly’ (X happens constantly during the time Y takes place).
Perfectivity, telicity and Estonian verbs
Authors: Tamm Anne
Published: December 2007

This paper discusses telicity and perfectivity in Estonian. Neither of these categories corresponds exactly to the Estonian object case alternation, which is argued to reflect predicate or clause aspectual properties and not the NP-related properties of objects. The aim of this account is to accommodate the systematic compatibility of verb classes with certain clausal aspectual object case marking patterns. The paper proposes a way of understanding the interaction between verbal and clausal aspect in terms of boundedness and formalizes it in the framework of Lexical Functional Grammar (LFG). The features of verbs and case markers determine the clausal aspect from different constituents at the syntactic level of constituent structure. The information is unified at another syntactic level, functional structure.
Analyzing progressives in Norwegian
Authors: Tonne Ingebjørg
Published: December 2007

In this paper, the Norwegian progressive forms are examined by way of a corpus study, including both a monolingual corpus and a Norwegian–English parallel corpus. The corpora reveal patterns and properties of Norwegian progressives that are novel compared to those of a well-studied aspectual system like that in English. The study shows that the progressives should be grouped into two subgroups, according to their combinatorial and semantic properties. The array of properties that is brought out by the examination of the monolingual and parallel corpora is accounted for in a formal semantic frame, based on works by Dowty (1979) and Krifka (1992, 1998), and also drawing on insights from, among others, Rothstein (1999, 2004).
The elimination of Chagas' disease from Brazil
Authors: MASSAD E.
Published: December 2007

On 9 June 2006 the Pan American Health Organization (PAHO) presented the Minister of Health of Brazil with the International Elimination of Transmission of Chagas' Disease Certificate. This act was the culmination of an intensive process that began in 1991 with the Southern Cone Initiative, a joint agreement between the governments of Argentina, Bolivia, Brazil, Chile, Paraguay, Uruguay and Peru, to control Chagas' disease by the elimination of the main vector, Triatoma infestans. This initiative has been highly successful and the prevalence area of the vector diminished rapidly in the last years. As a consequence, the current seroprevalence in children aged between 0 and 5 years is of the order of 10−5, a clear indication that transmission, if it is occurring, is only accidental. In this review I calculate the basic reproduction number, R0, for Chagas' disease and demonstrate that its relatively low value (1·25) explains why vectorial transmission was interrupted relatively easily. In addition, I used a mathematical model to forecast how long the remaining cases of the disease, as well as the additional vertically transmitted cases will last.
The seasonality of human cryptosporidiosis in New Zealand
Authors: LAKE I. R. , PEARCE J. , SAVILL M.
Published: December 2007

In New Zealand human cryptosporidiosis demonstrates spring and autumn peaks of incidence with the spring peak being three times greater in magnitude than the autumn peak. The imbalance between the two peaks is notable, and may be associated with the high livestock density in New Zealand. In the summer and autumn the cryptosporidiosis rate was positively associated with temperatures in the current and previous month, highlighting the importance of outdoor recreation to transmission. No associations between spring incidence and weather were found providing little support for the importance of drinking-water pathways. Imported travel cases do not appear to be an important factor in the aetiology of cryptosporidiosis in New Zealand.
Mining pesticide use data to identify best management practices
Authors: Oakley Emily , Zhang Minghua , Miller Paul Richard
Published: December 2007

This paper reports on the initial findings of an ongoing research project to capture differences in pest management strategies and decision-making among growers using the California Pesticide Use Reports (PUR) database. Analysis was performed for prunes in Sutter and Yuba counties to identify on-farm innovation by analyzing the PUR for best management practices to reduce pesticide use. Results showed that large variations in pesticide use were present in 2000, with a range of less than 5 kg to more than 41 kg of pesticide applied per hectare (ha) crop planted in Sutter County and a range of less than 2 kg to close to 30 kg per ha crop planted in Yuba County. Among the 42 growers selected cultivating more than 80 ha, five growers in Sutter County and three growers in Yuba County in 2000 were identified as low pesticide use growers. The results indicated a surprising number of low to no fungicide users and an even higher number of growers using no herbicides in both counties. Twenty-nine viable low pesticide use growers were identified overall among the total 294 growers in the Sutter and Yuba counties. However, there were no spatial patterns of where these low pesticide use growers' fields were located. The transition from higher-risk active ingredients (AIs) to reduced-risk AIs used by many of the low pesticide users suggests intentional substitution. Initial yield data indicate that quantity and quality were not adversely affected by low use growers employing reduced-risk pesticides, fewer (AIs) per field, and lower rates per chemical than their moderate to high use counterparts. Diverse collaborators consisting of university researchers, environmental and community organizations, state government scientists, and growers worked together throughout the entire project, beginning with defining the research parameters, then interpreting the results, and finally suggesting practical applications for the outcomes. The paper also highlights the effectiveness of using such collaborative research relationships to explore low pesticide use alternatives, to directly exchange research findings with growers, and to encourage a farmer-to-farmer extension model.
Work: A necessary sacrifice or a suffered chore? Labor and farm continuity in alternative agriculture in France
Authors: Macombe Catherine
Published: December 2007

Systems advocating alternative agriculture would appear to be handicapped by the amount and the minutiae of human labor required. Is this really a threat to the continuity of farms associated with these systems? We do not believe that this directly hampers the survival of a farm. We advance the theory that continuity is not just down to chance; the farmer at the time chooses to prolong the life of the farm and more especially to look for a successor. We have shown through a study conducted in central France (Auvergne) that the main guarantee of organizational sustainability, that which sustains the business as a viable entity when another person takes over, is when a farmer thinks of his farm as an entity-cum-project supporting a meaningful life plan. A farmer might also see his farm solely as capital or as heritage, but neither of these last two attitudes is sufficient for him to ensure the spirit of his enterprise is passed on. There is a particularly large number of farmers in the first category (entity-cum-project) who adopt alternative farming practices, which are meaningful. It also seems to be the case that the manner of working is closely linked to the moral principles of farmers who use alternative systems. Moreover, the same objective amount of work that might be thought excessive in a system that puts strong emphasis on high productivity, is regarded as normal in an alternative system. Farmers often approach extension advisors to help reorganize their working conditions. We maintain that alternative systems have peculiarities with regard to work that make this type of advice difficult. Our aim is to help advisors clearly construct the input they give to the various types of farmers. We put forward a typology of possible practices as regards advice on work, according to assessments farmers have made about the amount of work they do and their way of working. The large number of hours devoted to an alternative farming activity and the nature of that activity, whether demanding or linked to practices thought archaic, are not always a handicap to the continuity of an alternative system. On the contrary, these features can be its hallmark.
Periphyton in rice–fish culture system: A case study from Arunachal Pradesh, India
Authors: Das D.N. , Saikia S.K. , Das A.K.
Published: December 2007

The farmers of the Apatani tribe in Arunachal Pradesh, India have been raising a concurrent crop of fish successfully in their mountain valley rice plots for the past 40 years. They follow indigenous rice agronomy, ignoring the use of fertilizers, pesticides and even supplementary feed for the fish reared in the system. However, the yield levels of fish, ranging from 250 to 500 kg ha−1season−1, clearly support the role of other available resources within their wet rice fields. The investigation revealed that the rice itself provided the substrates for colonization and growth of periphyton. The colonized periphytic contents (1406–13513 no. cm−2stem−1) on rice stems and other natural fish feeds within the system seem to have direct effect in this regard. The Apatani technique of rice–fish integration may be considered as one of the periphyton-based aquaculture (PBA) systems which deserve further research attention.
Evaluation of different pig slurry composts as fertilizer of horticultural crops: Effects on selected chemical and microbial properties
Authors: Ros Margarita , García Carlos , Teresa Hernandez Maria
Published: December 2007

The excessive use of mineral fertilizers affects soil quality, gives rise to environmental problems and consumes energy. In contrast, organic amendment may improve soil quality at the same time as providing nutrients to plant. The aim of the work was to study the effects on crop yield and soil microbial activity of the successive addition of mineral fertilizers and fresh pig slurry before each successive crop compared with one sole application of different pig slurry composts (solid fraction of a pig slurry (CSFPS) and fresh pig slurry plus wood shavings (1:1 v/v; CPS+WS) before planting the first crop. Compost-treated soils exhibited higher organic carbon content than inorganically fertilized soils, throughout the experimental period. However, N content in the former soils was lower than in the latter after the second crop. Nevertheless, yields obtained with repeated additions of fresh pig slurry or with a sole application of pig slurry composts were similar to those obtained with repeated mineral fertilization. After the horticultural crops, organically treated soils generally showed higher values of both microbial biomass and metabolic microbial activity (measured as basal respiration and dehydrogenase activity) than the soil receiving mineral fertilization. Subsequently, the organically amended soils showed higher protease, phosphatase and β-glucosidase activities than the inorganically fertilized soil and similar levels of urease activity. From this study it can be concluded that both fresh and composted pig slurry can be used as an alternative for mineral fertilizer in growing horticultural crops and maintaining soil quality.
The spatial temporal regime of stream flow of the conterminous U.S. in connection with indices of global atmospheric circulation
Authors: Shmagin Boris , Johnston Carol , Bridgham Scott
Published: December 2007

Long-term stream flow records (1929-1988) from seventy one U.S. Geological Survey gauging stations with drainage area in range 1000-10000 sq mi were analyzed using multivariate statistics. Factor analysis of average annual flow revealed seven patterns of river runoff within seven distinct regions of the territory. This factor model reflected 69% variance of the initial matrix. The second set of stream flow records (1939-1972) from ninety-seven gauging stations was used as control. This set contains all seventy one from first one and additional stations with shorter observation period. Factor analysis of this expended set again yielded seven factors (69% variance of the initial matrix) with very similar spatial distribution of gauging stations.Every group of watersheds obtained as a factor was presented by one gauging station with time series of annual discharges (1- 05474000, 2- 14321000, 3- 07019000, 4- 0815000, 5- 11186001, 6- 01666000, 7- 06800500) as the most typical for group. For the same time interval, streams represented by all patterns have increasing values (i. e. the positive difference between two time subintervals); but only the positive linear trend for patterns 1 and 7 are statistically significant. For the seven typical flow records, monthly average values were obtained from three to five seasons composed from different ensembles of months. For each annual time series of the typical seven stream flow patterns, regression equations were obtained from indices of global atmospheric circulation (AO, NAO, NPO and AAO). The equations contain from one to five variables (predictors) and have coefficients of correlation from 32% to 73%.
Response Method in Audiometry
Authors: DiGiovanni Jeffrey J. , Repka Jennifer N.
Published: December 2007

Purpose

This study compared the speed, false-alarm rate, and participant preference of different response methods (raising a hand, pushing a response button, and giving an oral response) for measuring pure-tone thresholds.

Method

Thirty female university students with normal hearing participated. Response method order was randomly assigned to 6 different groups. Air-conduction thresholds were measured twice for each response method for each participant in octave intervals between 250 Hz and 8000 Hz. The 2nd threshold measurements were performed on a different day but within 2 weeks of the initial measurement.

Results

A significant difference was found when comparing the amount of time necessary to complete the test for each response method. On average, it took about 1 min less when using the push-button response than when using hand-raise or verbal response methods. There was also a significant participant preference for using the response button. No significant difference between response method for threshold level and number of false positives was found.

Conclusion

This study supports the use of the response button when measuring auditory thresholds for young adults with normal hearing.
Perceived Hearing Status and Attitudes Toward Noise in Young Adults
Authors: Holmes Alice E. , Widén Stephen E. , Erlandsson Soly , Carver Courtney L. , White Lori L.
Published: December 2007

Purpose

To estimate the prevalence of perceived hearing loss, tinnitus, and temporary threshold shift (TTS) in community college students and to see whether those students' attitudes toward noise affected their perception of their own possible hearing loss, tinnitus, and TTS.

Method

Young adults (N= 245; age 18–27) completed 3 questionnaires: the Hearing Symptom Description, Youth Attitude to Noise Scale, and Adolescents' Habits and Hearing Protection Use.

Results

Perceived TTS and pain associated with loud noise were the most common hearing related factors, followed by perceived tinnitus and hearing loss. The students' attitudes toward noise in their daily environment showed the most negative response, whereas attitudes toward noise and concentration indicated a more positive, or less harmful, response. Chi-square analysis indicated a significant correlation between perceived hearing loss and respondents' overall attitudes toward noise exposure. Hearing protection use was limited for all participants, with the majority reporting never having used hearing protection.

Conclusion

Approximately 6% of respondents reported perceived hearing loss, and 13.5% reported prolonged tinnitus. In general, participants had neutral attitudes toward noise. Over 20% of participants reported ear pain, tinnitus, and/or TTS after noise exposure at least sometimes. Coincidentally, few participants reported consistent use of hearing protection.
Is the V-form the Next Generation Organisation? An Analysis of Challenges, Pitfalls and Remedies of ICT-enabled Virtual Organisations Based on Social Capital Theory
Authors: Riemer Kai , Klein Stefan
Published: December 2007

ICT-enabled virtual organisations (VOs) are regarded as the appropriate organisational response to turbulent markets. Although much has been written about the structural characteristics and propositions of VOs, their inherent limitations and structural shortcomings remain largely unaddressed. Based on the structural properties of VOs, most frequently discussed in the literature, we introduce the V-form organisation as an ideal type of VOs. A conceptual analysis, however, reveals a mismatch between espoused benefits of the ideal type and preconditions in terms of collaborative practices needed to succeed in a turbulent environment. Dealing with complex tasks in a collaborative environment requires shared understanding, shared values and a level of social cohesion, which do not simply emerge in a virtual setting. Social capital theory addresses the social and cultural preconditions of collaboration. Our analysis shows preconditions for successful value creation in VOs and suggests management measures to foster and facilitate environments for the development of social capital.
ICTs and Poverty Reduction: A Social Capital and Knowledge Perspective
Authors: Urquhart Cathy , Liyanage Shantha , Kah Muhammadou MO
Published: December 2007

The efficacy of information and communication technology (ICT) projects and initiatives in developing countries, and how they may assist poverty reduction or otherwise improve the quality of life for communities in those countries, is still a topic of debate. Knowledge empowers people, while information technology integrates such knowledge for purposeful action and reaction. This paper describes a framework, based on social capital and knowledge management theories, which aims to further that debate in the field of information systems. The framework is primarily a sensitising device, designed to assist thinking about how social capital and knowledge theories facilitate ICT interventions for poverty reduction. The framework has four stages, the process of ICT development, the ICT intervention, the evaluation of the impact of the ICT intervention and the process of poverty reduction, which is the final and most contested stage of an ICT intervention. Each stage of the framework is discussed, using illustrations from various development projects. Finally, the paper draws some conclusions about the contribution of social capital and knowledge management theories to the issue of ICT intervention and evaluation in developing countries.
Adiabatic approximation of time-dependent density matrix functional response theory
Authors: Pernal Katarzyna , Giesbertz Klaas , Gritsenko Oleg , Baerends Evert Jan
Published: December 2007

Time-dependent density matrix functional theory can be formulated in terms of coupled-perturbed response equations, in which a coupling matrix K(ω) features, analogous to the well-known time-dependent density functional theory (TDDFT) case. An adiabatic approximation is needed to solve these equations, but the adiabatic approximation is much more critical since there is not a good “zero order” as in TDDFT, in which the virtual-occupied Kohn-Sham orbital energy differences serve this purpose. We discuss a simple approximation proposed earlier which uses only results from static calculations, called the static approximation (SA), and show that it is deficient, since it leads to zero response of the natural orbital occupation numbers. This leads to wrong behavior in the ω→0 limit. An improved adiabatic approximation (AA) is formulated. The two-electron system affords a derivation of exact coupled-perturbed equations for the density matrix response, permitting analytical comparison of the adiabatic approximation with the exact equations. For the two-electron system also, the exact density matrix functional (2-matrix in terms of 1-matrix) is known, enabling testing of the static and adiabatic approximations unobscured by approximations in the functional. The two-electron HeH+ molecule shows that at the equilibrium distance, SA consistently underestimates the frequency-dependent polarizability α(ω), the adiabatic TDDFT overestimates α(ω), while AA improves upon SA and, indeed, AA produces the correct α(0). For stretched HeH+, adiabatic density matrix functional theory corrects the too low first excitation energy and overpolarization of adiabatic TDDFT methods and exhibits excellent agreement with high-quality CCSD (“exact”) results over a large ω range.
Waves on unsteady currents
Authors: Haller Merrick C. , Tuba Özkan-Haller H.
Published: December 2007

Models for surface gravity wave propagation in the presence of currents often assume the current field to be quasi-stationary, which implies that the absolute wave frequency is time invariant. However, in the presence of unsteady currents or time-varying water depth, linear wave theory predicts a time variation of the absolute wave frequency (and wavenumber). Herein, observations of wave frequency modulations from a large-scale laboratory experiment are presented. In this case, the modulations are caused by both unsteady depths and unsteady currents due to the presence of low-frequency standing waves. These new observations allow a unique and detailed verification of the theoretical predictions regarding variations in the absolute wave frequency. In addition, analytic solutions for the variations in frequency and wave height induced by the unsteady medium are found through a perturbation analysis. These solutions clarify the dependency of the wave frequency/wave height modulations on the characteristics of the unsteady medium. We also find that analytic solutions for simplified basin configurations provide an order of magnitude estimate of the expected frequency modulation effect. Finally, the importance of this phenomenon in natural situations is discussed.
Nucleosynthesis driven by Coulomb explosion of nanodroplets
Authors: Last Isidore , Jortner Joshua
Published: December 2007

This paper presents a computational and theoretical study of the yields for the C12(p,γ)N13 and C12(d,n)N13 nucleosynthesis reactions driven by high-energy (MeV) Coulomb explosion (CE) of (CH4)n and (CD4)n nanodroplets (n=104–107, radii R0=100–500Å) in ultraintense near-infrared Gaussian laser fields (peak intensities IM=1018–1019Wcm−2, pulse length τ=25fs). Efficient nucleosynthesis with C12 nuclei requires the production of protons and deuterons in the energy range of 0.5–2.0MeV, which is accomplished by CE of nanodroplets. The energy distributions of the nuclei were obtained from scaled molecular dynamics simulations and were utilized to calculate the energy averaged cross sections and the reaction yields for nucleosynthesis. Two distinct reaction modes were established pertaining to reactions inside the plasma filament volume (IF), and to reactions outside the plasma filament volume (OF). The dominating contribution to the total yields originates from the OF mode. The time resolved γ-ray emission for C12(p,γ)N13 will be exhibited in distinct time intervals of 2–100ps for the OF mode and of 65fs–3ps for the IF mode. Estimates of the yields were provided by incorporating the effects of nanodroplet size distributions that result in a slow size dependence of the yields in the range R0>250Å, and the effects of laser intensity attenuation in an assembly of nanodroplets that result in the decrease of the OF and IF yields due to the decrease of the effective plasma filament volume. For 400Å nanodroplets at IM=4×1018–1019Wcm−2, under realistic experimental conditions, the C12(p,γ)N13 nucleosynthesis driven by CE of (CH4)n nanodroplets is characterized by a yield (per laser pulse) of ∼100, while the yield for the C12(d,n)N13 nucleosynthesis driven by CE of (CD4)n clusters is ∼9×104. Table-top nucleosynthesis driven by nanodroplet CE is amenable to experimental observation.
Generalized definition of time delay in scattering theory
Authors: Gérard Christian , Tiedra de Aldecoa Rafael
Published: December 2007

We advocate for the systematic use of a symmetrized definition of time delay in scattering theory. In two-body scattering processes, we show that the symmetrized time delay exists for arbitrary dilated spatial regions symmetric with respect to the origin. It is equal to the usual time delay plus a new contribution, which vanishes in the case of spherical spatial regions. We also prove that the symmetrized time delay is invariant under an appropriate mapping of time reversal. These results are also discussed in the context of classical scattering theory.
Widely tunable single-mode quantum cascade laser source for mid-infrared spectroscopy
Authors: Lee Benjamin G. , Belkin Mikhail A. , Audet Ross , MacArthur Jim , Diehl Laurent , Pflügl Christian , Capasso Federico , Oakley Douglas C. , Chapman David , Napoleone Antonio , Bour David , Corzine Scott , Höfler Gloria , Faist Jérôme
Published: December 2007

We demonstrate a compact, single-mode quantum cascade laser source continuously tunable between 8.7 and 9.4μm. The source consists of an array of single-mode distributed feedback quantum cascade lasers with closely spaced emission wavelengths fabricated monolithically on a single chip and driven by a microelectronic controller. Our source is suitable for a variety of chemical sensing applications. Here, we use it to perform absorption spectroscopy of fluids.
Contactless electroreflectance approach to study the Fermi level position in GaInNAs/GaAs quantum wells
Authors: Kudrawiec R. , Yuen H. B. , Bank S. R. , Bae H. P. , Wistey M. A. , Harris James S. , Motyka M. , Misiewicz J.
Published: December 2007

A fruitful approach to study the Fermi level position in GaInNAs/GaAs quantum wells (QWs) has been proposed in this paper. This approach utilizes contactless electroreflectance (CER) spectroscopy and a very simple design of semiconductor structures. The idea of this design is to insert a GaInNAs quantum well (QW) into a region of undoped GaAs layer grown on n-type GaAs substrate. The possible pinning of the Fermi level in the GaInNAs QW region modifies band bending in this system. In CER spectra both QW transitions and GaAs-related Franz-Keldysh oscillations (FKOs) are clearly observed. The analysis of QW transitions allows one to determine the band gap discontinuity at GaInNAs/GaAs interface whereas the analysis of FKOs allows one to determine the built-in electric field in the GaAs cap layer, and, finally, one is able to find the Fermi level pinning in GaInNAs QW region.
Barrier inhomogeneity and electrical properties of Pt∕GaN Schottky contacts
Authors: Iucolano Ferdinando , Roccaforte Fabrizio , Giannazzo Filippo , Raineri Vito
Published: December 2007

The temperature dependence of the electrical properties of Pt∕GaN Schottky barrier was studied. In particular, a Schottky barrier height of 0.96eV and an ideality factor of 1.16 were found after a postdeposition annealing at 400°C. Nanoscale electrical characterization was carried out by the conductive biased tip of an atomic force microscope both on the bare GaN surface and on the Pt∕GaN contacts. The presence of a lateral inhomogeneity of the Schottky barrier, with a Gaussian distribution of the barrier height values, was demonstrated. Moreover, GaN surface defects were demonstrated to act as local preferential paths for the current conduction. The temperature dependent electrical characteristics of the diodes were discussed in terms of the existing models on inhomogeneous barriers and correlated to the nanoscale electrical characterization of the barrier. In this way, the anomalous electrical behavior of the ideality factor and of the Schottky barrier and the low experimental value of the Richardson’s constant were explained.
Violet to deep-ultraviolet InGaN∕GaN and GaN∕AlGaN quantum structures for UV electroabsorption modulators
Authors: Ozel Tuncay , Sari Emre , Nizamoglu Sedat , Demir Hilmi Volkan
Published: December 2007

In this paper, we present four GaN based polar quantum structures grown on c-plane embedded in p-i-n diode architecture as a part of high-speed electroabsorption modulators for use in optical communication (free-space non-line-of-sight optical links) in the ultraviolet (UV): the first modulator incorporates ∼4–6nm thick GaN∕AlGaN quantum structures for operation in the deep-UV spectral region and the other three incorporate ∼2–3nm thick InGaN∕GaN quantum structures tuned for operation in violet to near-UV spectral region. Here, we report on the design, epitaxial growth, fabrication, and characterization of these quantum electroabsorption modulators. In reverse bias, these devices exhibit a strong electroabsorption (optical absorption coefficient change in the range of 5500–13000cm−1 with electric field swings of 40–75V∕μm) at their specific operating wavelengths. In this work, we show that these quantum electroabsorption structures hold great promise for future applications in ultraviolet optoelectronics technology such as external modulation and data coding in secure non-line-of-sight communication systems.
Synthesis and Structure - Activity Relationship Analysis of Enamines as Potential Antibacterial Agents
Authors: Xue Jia-Yu , Xiao Zhu-Ping , Shi Lei , Tan Shu-Hua , Li Huan-Qiu , Zhu Hai-Liang
Published: December 2007

Twenty-four new enamines [(Z)-4–15 and (E)-4–15] were synthesized for the first time. Their chemical structures were determined by means of 1H NMR spectroscopy, electrospray ionization-mass spectrometry, and elemental analysis. All of the compounds were assayed for antibacterial (Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Pseudomonas fluorescens ATCC 13525, and Staphylococcus aureus ATCC 6538) and antifungal (Aspergillus niger ATCC 16404, Candida albicans ATCC 10231, and Trichophyton rubrum ATCC 10218) activities by the 3-(4,5-dimethyl thiazole-2yl)-2,5-diphenyl tetrazolium bromide (MTT) method. Four compounds, (E)-ethyl 3-(4-fluorophenylamino)-2-(3-methoxyphenyl)acrylate ((E)-6), (E)-ethyl 3-(4-chlorophenylamino)-2-(3-methoxyphenyl)acrylate ((E)-9), (E)-ethyl 3-(4-bromophenylamino)-2-(3-methoxyphenyl)acrylate ((E)-12), and (E)-ethyl 3-(2,4-dibromophenylamino)-2-(3-methoxyphenyl)acrylate ((E)-13) showed considerable antibacterial activity against Pseudomonas fluorescens with minimum inhibitory concentrations of 12.5, 12.5, 3.12, and 6.25 μg mL–1, respectively. Structure–activity relationship analyses revealed that, in general, an (E)-isomer exhibited higher antibacterial activity than the corresponding (Z)-isomer.
Naphthopyrans and their C4 Alcohols by Cyclization of Substituted Naphthalenes using Potassium t-Butoxide in Dimethylformamide. Generality and Stereochemical, including Conformational, Effects
Authors: Giles Robin G. F. , Green Ivan R. , Swigelaar Wendell P. , Taylor C. Peter
Published: December 2007

The generality of the high-yielding, stereoselective cyclization of 2-allyl-3-(1′-hydroxyethyl)-1,4-dimethoxynaphthalene 1 to afford trans-3,4-dihydro-5,10-dimethoxy-1,3-dimethylnaphtho[2,3-c]pyran 2 is investigated by replacing each of the methoxy groups in the substrate by an ethyl substituent and subjecting these to cyclization reaction conditions identical to those originally reported. For shorter reaction times with potassium tert-butoxide in dimethylformamide under nitrogen, the derived 1-ethyl-, 4-ethyl-, and 1,4-diethylnaphthalenes all cyclize to the trans-1,3-dimethyl compounds, whereas longer times yield increasing proportions of the corresponding cis-isomers. Under air, the epimeric C4 alcohols rel-(1R,3R,4S)-3,4-dihydro-5-ethyl-4-hydroxy-10-methoxy-1,3-dimethylnaphtho[2,3-c]pyran 50 and its rel-(1R,3R,4R) isomer 51 are also isolated from 2-allyl-1-ethyl-3-(1′-hydroxyethyl)-4-methoxynaphthalene 11. The half-chair conformation of pyran 50 is inverted relative to that of its C4 epimer 51.
A Speedy One-Pot Synthesis of Second-Generation Ionic Liquids Under Ultrasound and/or Microwave Irradiation
Authors: Cravotto Giancarlo , Boffa Luisa , Lévêque Jean-Marc , Estager Julien , Draye Micheline , Bonrath Werner
Published: December 2007

The present work describes an efficient one-pot synthesis of second-generation ionic liquids (ILs), combining in one step the Menshutkin reaction and anion metathesis. Working in a closed vessel under microwaves, or better still under simultaneous ultrasound and/or microwave irradiation, in a few minutes a series of ILs with 1-methylimidazole or pyridine cores were obtained in high yields (80–97% isolated). Under conventional heating, ILs could not be prepared in one pot in acceptable times and yields, whereas our protocol, carried out with commercially available equipment, was highly effective and reproducible. Moreover, 1H NMR analysis and ion-exchange chromatography showed that the present solventless procedure afforded satisfyingly pure ILs.
Pseudomonas syringae
type III effector AvrRpt2 alters
Arabidopsis thaliana
auxin physiology
Authors: Chen Zhongying , Agnew Jennifer L. , Cohen Jerry D. , He Ping , Shan Libo , Sheen Jen , Kunkel Barbara N.
Published: December 2007

The
Pseudomonas syringae
type III effector AvrRpt2 promotes bacterial virulence on
Arabidopsis thaliana
plants lacking a functional
RPS2
gene (
rps2
mutant plants). To investigate the mechanisms underlying the virulence activity of AvrRpt2, we examined the phenotypes of transgenic
A. thaliana rps2
seedlings constitutively expressing AvrRpt2. These seedlings exhibited phenotypes reminiscent of
A. thaliana
mutants with altered auxin physiology, including longer primary roots, increased number of lateral roots, and increased sensitivity to exogenous auxin. They also had increased levels of free indole acetic acid (IAA). The presence of AvrRpt2 also was correlated with a further increase in free IAA levels during infection with
P. syringae
pv.
tomato
strain DC3000 (
Pst
DC3000). These results indicate that AvrRpt2 alters
A. thaliana
auxin physiology. Application of the auxin analog 1-naphthaleneacetic acid promoted disease symptom development in
Pst
DC3000-infected plants, suggesting that elevated auxin levels within host tissue promote
Pst
DC3000 virulence. Thus, AvrRpt2 may be among the virulence factors of
P. syringae
that modulate host auxin physiology to promote disease.