Spread Of Carriers Research Articles

Modelling the spread of cystic fibrosis in Brittany using genealogical data over five centuries

BackgroundThe French region of Brittany presents one of the highest cystic fibrosis (CF)-causing allele frequency in Europe. Here, we tested two hypotheses: i) CF-causing allele carriers arrived by sea in the middle of the 1st millennium AD, and ii) a selective advantage for healthy carriers explains this high rate. MethodsFrom the census of cystic fibrosis patients, frequency maps of the most widespread alleles were established. A mathematical model was developed, based on birth date and place of the ancestors of these patients over 5 centuries, to determine the distribution of local migrations and their parameters for inter-generational intervals of 32 years. This model was applied to simulate the spread of CF-causing variant carriers, according to different scenarios that corresponded to the immigration of a given number of variant carriers at different times (year) and places, and to compare their results to current frequency maps. ResultsMigrants carrying a CFTR variant settled in several locations, around which they spread, notably in Central Brittany (F508del variant), Léon (G551D variant) and Cornouaille (1078delT variant). Until the end of the 18th century, the spreading of disease-causing allele carriers was relatively slow, and allele frequencies progressively increased. Then, the mean migration distances increased rapidly, leading to a decline in local frequencies. ConclusionsThe main CFTR variants could only have reached their current frequencies through a selective advantage for healthy carriers of the order of 4–6 % at each generation. For the most widespread variant (F508del), the model supports the hypothesis that it appeared around 190 generations ago.

Clinical, pathological and genetic aspects of laryngeal paralysis in dogs

The review article discusses the main clinical signs of paralysis of the larynx and pathological changes associated with it and other neurological pathologies. These hereditary canine neuropathies form a group of degenerative diseases affecting motor and/or sensory and autonomic peripheral nerves and have similar symptoms.Axonal forms associated with generalized polyneuropathy and paralysis of the larynx have been described in several dog breeds: Dalmatians, Alaskan Malamutes, Rottweilers, Labrador Retrievers, Leonbergers, St. Bernards, Italian Spinols, Pyrenean Mountain Dogs, Podhale Sheepdogs, Cocker Spaniels, Great Danes, American Staffordshire Terriers, Staffordshire Bull Terriers, Bouvier de Flandres, Siberian Huskies and Siberian Husky crosses. Candidate genes for association with the disease are considered: ARHGEF10, RAPGEF6, ADAMTS3, CNTNAP1, DCTN1. The age of onset of the disease can be different, the manifestation of signs of paralysis of the larynx occurs both in young dogs, and the geriatric form also occurs. The prognosis of the complex of paralysis of the larynxpolyneuropathy is from cautious to unfavorable. One case of euthanasia due to intractable regurgitation and aspiration pneumonia has been described. Some authors point to a possible association of the disease with white coat color. Two main types of inheritance of paralysis of the larynx in dogs have been established - autosomal recessive and X -linked recessive. In humans, the dominant type of inheritance of this anomaly is known. Early diagnosis will make it possible to identify the hereditary nature of paralysis of the larynx, reduce the incidence of severe forms of the disease with timely surgical correction of the cartilage of the larynx and symptomatic treatment, as well as the spread of carriers of mutant alleles in dog populations. This is relevant today in connection with the spread of this anomaly in many breeds.

Argas ticks (Ixodida: Argasidae) on migratory birds from Africa: first record of a genotype close to Argas africolumbae in Italy

In spring, migratory birds reach Europe, mainly from sub-Saharan Africa or from northern African countries. Avian species may be implicated in the spread of pathogens, either as reservoirs, hosts or carriers of infected ectoparasites. In 2021, on Ventotene Island (Latium region, Italy) within a project focused on the potential incoming pathogens via migratory birds from Africa, we found two larvae of Argas sp., on the redstart Phoenicurus phoenicurus, that shared morphological features with the African Argas (Argas) africolumbae. Comparison of the tested larval DNA sequences to the adult reference sequences showed the highest identity (> 92%) with homologous sequences of A. africolumbae collected in South Africa and in Spain. This study reports the first detection of Argas africolumbae-like specimens in Italy.

Hantavirus Diseases: a Review of Epidemiological Situation and Epidemiological Risks in the Regions of the World

The purpose of this review is to characterize the current epidemiological and epizootiological situation in natural foci of hantavirus diseases in different regions of the world, and to analyze the literature data available. Currently, hantavirus diseases are a very urgent threat to the sanitary and epidemiological well-being of the population around the world, which can cause serious complications of the epidemiological situation. About 200 thousand cases of the disease are registered every year around the world, while the intensity and dynamics of the incidence varies significantly in different regions of the world. While in China – the country with the largest annual number of cases worldwide – the overall dynamics of the incidence has a downward trend, which is apparently due to the widespread use of specific disease prevention tools; the number of cases in European countries, on the contrary, shows a clear increase. In the Russian Federation, hemorrhagic fever with renal syndrome (HFRS) is currently the most common natural-focal disease of viral etiology. Data on the prevalence of hantavirus infection in the regions of South-East Asia and the African continent require further investigation, but it is quite obvious that hantavirus infection is a very underestimated public health issue in these regions, and its scale, due to the wide spread of carriers, may be much more considerable than is currently known.

Fecal carriage and molecular epidemiologic characteristics of carbapenemase-producing Enterobacterales in primary care hospital in a Japanese city

BackgroundThe worldwide spread of organisms with antimicrobial resistance is of concern, especially the trend of significantly increasing carbapenemase-producing Enterobacterales (CPE). In this study, we investigated the annual trend of intestinal CPE carriage rates in inpatients and healthy adults in a primary care hospital in Tenri, Japan. MethodsWe collected 551 samples of feces from inpatients in our institution and 936 samples from healthy people living in Tenri city from December 2012 to April 2015. All samples were cultured on MacConkey agar plates containing 4 μg/mL ceftazidime for screening test. The colonies grown on the screening medium were detected for carbapenemase genes (blaIMP-1, blaIMP-2, blaVIM, blaKPC, blaGES, blaNDM, and blaOXA-48 groups) by multiplex PCR, and CPE were identified by MALDI-TOF MS. Plasmid replicon typing and pulsed-field gel electrophoresis (PFGE) were performed on PCR-positive strains. ResultsThe CPE carriage rate was 1.6% (9/551) in the inpatient group and 0% (0/936) in the healthy adults group. The numbers of strains positive for the carbapenemase gene were 4 for Enterobacter cloacae, 2 for Klebsiella pneumoniae, 1 for Citrobacter freundii, 1 for Raoultella ornithinolytica and 1 for Escherichia coli. In all CPE strains, the carbapenemase gene was blaIMP-6 and the plasmid replicon type was IncN. The 4 E. cloacae strains showed a similar pattern in PFGE. ConclusionIn the same city in Japan, CPE intestinal carriers were detected only in the inpatient group in this study but not in a healthy adults, suggesting that the spread of asymptomatic CPE carriers was confined to inpatients.

Control over the inherited diseases of Ayrshire and Aberdeen Angus cattle breeds on the Russian Federation territory

In the paper have been described the inherited diseases AH1 and FMO3 charactering for Ayrshire cattle breed and AM, OS and DD, charactering for Aberdeen Angus one, particularly, the clinical signs and causing gene mutations. The aim of the study was a genotyping of Ayrshire and Aberdeen Angus breeds cattle of Russian populations by earlier developed DNA tests and the evaluation of the spread of animal carriers. The analysis of two populations of Ayrshire cows (n=268) and three populations of Aberdeen Angus (n=772) sire bulls has shown the presence of animals carriers of the genetic defect of AH1 and FMO3 among the Russian Ayrshire populations in 6.33-15.79% and 7.69-46.15% frequencies, respectively. In addition, in Subpopulation 5b three FMO-affected animals were found (3.03%). The animals carriers of AM and DD genetic defects have been found in Russian Aberdeen Angus populations in the frequencies of 0.63-2.73 and 1.13-9.49% dependently from the populations, respectively. In addition, we have observed the increasing of the frequencies of AMC- and DDC-animals in the subpopulations of descendants of populations 1 and 2. The increasing of AMC-animals in Subpopulation 2b comparing with 2a was statistically significant.

Effect of temperature and ridge-width on the lasing characteristics of InAs/InP quantum-dash lasers: A thermal analysis view

We investigate the thermal characteristics of multi-stack chirped barrier thickness InAs/InGaAlAs/InP quantum-dash-in-a-well lasers of different ridge widths 2, 3, 4 and 15µm. The effect of varying this geometrical parameter on the extracted thermal resistance and characteristic temperature, and their stability with temperature are examined. The results show an inverse relation of ridge-width with junction temperature with 2µm device exhibiting the largest junction temperature buildup owing to an associated high thermal resistance of ∼45°C/W. Under the light of this thermal analysis, lasing behavior of different ridge-width quantum-dash (Qdash) lasers with injection currents and operating temperatures, is investigated. Thermionic carrier escape and phonon-assisted tunneling are found to be the dominant carrier transport mechanisms resulting in wide thermal spread of carriers across the available transition states of the chirped active region. An emission coverage of ∼75nm and 3dB bandwidth of ∼55nm is exhibited by the 2µm device, thus possibly exploiting the inhomogeneous optical transitions to the fullest. Furthermore, successful external modulation of a single Qdash Fabry-Perot laser mode via injection locking is demonstrated with eye diagrams at bit rates of 2–12Gbit/s incorporating various modulation schemes. These devices are being considered as potential light sources for future high-speed wavelength-division multiplexed optical communication systems.

The action of silicon doping in the first two to five barriers of eight periods In0.2Ga0.8N/GaN multiple quantum wells of blue LEDs

First two to five barriers in the growth sequence having silicon (Si) doping of eight periods In0.2Ga0.8N/GaN quantum wells (QWs) on twenty pairs of In0.02Ga0.98N/GaN superlattice strain relief layers (SRLs) of blue LEDs were prepared by low pressure metal–organic chemical vapor deposition (LPMOCVD) system on patterned sapphire substrates (PSSs). The effect of doping layers on the luminescence properties of QWs of blue LEDs was investigated. For the sample with first four barriers having Si doping, formation of soft confinement of QWs potential and strong carrier localization inside QWs were occurred. There is better spread of carriers among eight QWs and strong radiative recombination of carriers inside QWs. The increase of output power and external quantum efficiency (EQE) is due to decrease of Auger processes, leakage of carriers out of QWs, and nonradiative recombination centers. The consequences demonstrate that first four barriers with Si doping possess the favorable doping condition for eight periods In0.2Ga0.8N/GaN QWs.

The influence of electron track lengths on the γ-ray response of compound semiconductor detectors

The charge-trapping effect in compound semiconductor γ-ray detectors in the presence of a uniform electric field is commonly described by Hecht׳s relation. However, Hecht׳s relation ignores the geometrical spread of charge carriers caused by the finite range of primary and secondary electrons (δ-rays) in the detector. In this paper, a method based on the Shockley–Ramo theorem is developed to calculate γ-ray induced charge pulses by taking into account the charge-trapping effect associated with the geometrical spread of charge carriers. The method is then used to calculate the response of a planar CdTe detector to energetic γ-rays by which the influence of electron track lengths on the γ-ray response of the detectors is clearly shown.

Investigation of layers' sheet resistance using the spread of mobile charge carriers

Abstract In this work, the insulating layer with a weakly conductive layer on its surface is charged with a needle electrode. The quantities that are measured and calculated are the transients of charging current and transferred charge. In addition, we calculate charge distribution in the weakly conductive layer at various moments of time, and potential kinetics. By comparing the calculation results with measurement data, it is possible to determine sheet resistance of the investigated weakly conductive layer. This sheet resistance can be also determined experimentally: during charging of the weakly conductive layer (deposited onto the insulating layer), the charging current and the deposited charge increase with decreasing sheet resistance of the weakly conductive material, hence its sheet resistance can be related to the measured charging current or to the deposited charge. The proposed method can be applied for measuring sheet resistances from 10+8 Ω/sq to 10+12 Ω/sq, and those measurements can be done in a second. It is also possible to use the contact-free method proposed in this work to measure various properties of the medium related to the material sheet resistance, e. g. relative air humidity, illumination, sample thickness, intensity of ionizing radiation, etc. This method is also suitable for measuring sheet resistance of island-type (discontinuous) layers, which is difficult to measure using usual methods. Results of this work make it possible to determine potential of a two-layer system consisting of a charged low-conductance layer and an insulator, as well as the radius of an electrographically developed area, which is important, for example, when the image is created using a needle electrode.

Study of the charge sharing in silicon pixel detector by means of heavy ionizing particles interacting with a Medipix2 device

The charge sharing effect has been investigated in a 300 μm thick silicon pixel detector bump-bonded to a Medipix2 readout chip and exposed to heavy ionizing particles of various energies, namely protons and alpha-particles. The lateral spread of the charge carriers from the interaction of a heavy ionizing particle in the silicon detector causes a sharing of the charge among adjacent pixels, giving a signal in clusters of multiple pixels of the Medipix2 device. A model of charge sharing, including the plasma effect on top of diffusion and drift processes has been compared to the measured lateral spread of the charge for bias voltage values beyond the full depletion voltage. Results of the measurements of the cluster size as a function of the energy and incidence angle of incoming heavy ionizing particles are also reported and compared with the model.

Low-cost airlines in Europe: Network structures after the enlargement of the European Union

The liberalization of the European air opened the strictly regulated European market, and contributed to the appearance and quick spread of the Low-Cost Carriers (LCCs). At the beginning of the 21st century the low cost traffic absolutely concentrated on the Western European market but after the enlargement of the European Union (EU) LCCs started their operations in Eastern Europe enlarging and enriching the former evolved network structures. The aim of this paper is to trace the evolution of the route network as a result of EU expansion. During the study we came to the conclusion that in the time period after the EU enlargement the European LCC traffic showed dynamic development, route networks widened and the number of accessible destinations doubled. Comparing the LCCs network structures we defined three main characteristics, which represents the North-South flows, the West-East routes and the mixed network structure.

Spread of Low-Cost Carriers: Tourism and Regional Policy Effects in Spain

Vera Rebollo J. F. and Ivars Baidal J. A. Spread of low-cost carriers: tourism and regional policy effects in Spain, Regional Studies. Low-cost carriers form the most dynamic segment in the international tourism traffic toward Spain. Their recent evolution shows high growth rates that contrast with the stagnation of traditional companies, a phenomenon which is part of the transformations experienced by the tourism market and air transport in Europe and which has caused both quantitative and qualitative changes in Spain's tourist activity. However, the effects of low-cost carrier operations go beyond the context of the tourism sector and affect land-use and infrastructure planning policies, gradually shaping a new scenario where the specialization of tourism in real estate along the Spanish Mediterranean coast becomes reinforced. Vera Rebollo J. F. et Ivars Baidal J. A. Le développement des transporteurs à faible coût: effets du tourisme et de la politique régionale en Espagne, Regional Studies. Les transporteurs à faible coût (LCC) constituent le segment le plus dynamique du tourisme international vers l'Espagne. Leur évolution récente fait apparaître des taux de croissance élevés qui contrastent avec la stagnation des compagnies classiques, phénomène qui s'inscrit dans les transformations que connaissent le marché du tourisme et le transport aérien en Europe et qui est à l'origine de modifications quantitatives et qualitatives du tourisme en Espagne. Toutefois, les effets des opérations des LCC vont au-delà de ce secteur et touchent également les politiques d'aménagement du territoire et de planification des infrastructures, donnant naissance progressivement à un nouveau scénario où la spécialisation du tourisme dans l'immobilier le long des côtes méditerranéennes en Espagne se voit renforcée. Transport aérien Transporteurs à faible coût Aéroports Tourisme Développement urbain Mobilité Vera Rebollo J. F. und Ivars Baidal J. A. Die Ausbreitung von Billigfluggesellschaften: Auswirkungen auf Fremdenverkehr und Regionalpolitik in Spanien, Regional Studies. Billigfluggesellschaften bilden das dynamischste Segment des internationalen Fremdenverkehrs in Spanien. Bei dieser neuen Entwicklung werden hohe Wachstumsraten verzeichnet, während traditionelle Gesellschaften eine Stagnation verzeichnen – ein Phänomen, das einen Bestandteil des Wandels im Bereich des Fremdenverkehrsmarkts und Flugverkehrs in Europa bildet und das zu einer quantitativen und qualitativen Veränderung der touristischen Aktivitäten in Spanien geführt hat. Die Auswirkungen der Geschäftstätigkeiten von Billigfluggesellschaften gehen jedoch über den Kontext des Fremdenverkehrssektors hinaus und betreffen auch die Politiken zur Planung von Bodennutzung und Infrastruktur, wobei allmählich ein neues Szenario entsteht, in dem sich die Spezialisierung des Fremdenverkehrs auf Immobilien entlang der spanischen Mittelmeerküste verstärkt. Flugverkehr Billigfluggesellschaften Flughäfen Fremdenverkehr Städtewachstum Mobilität Vera Rebollo J. F. y Ivars Baidal J. A. La expansión de las compañías aéreas de bajo coste: incidencia en la política regional y turística en España, Regional Studies. Las LCC's constituyen el segmento más dinámico del tráfico turístico internacional hacia España. Su evolución reciente muestra elevadas tasas de crecimiento frente al estancamiento de las compañías tradicionales, un fenómeno que forma parte de las transformaciones que experimenta el mercado turístico y del transporte aéreo europeo y que ha provocado cambios cuantitativos y cualitativos en la actividad turística española. Sin embargo, sus efectos superan el ámbito sectorial-turístico para afectar a las políticas de ordenación del territorio y planificación de infraestructuras, configurando paulatinamente un nuevo escenario en el que se refuerza la especialización inmobiliaria del turismo en la costa mediterránea española. Transporte aéreo Compañías de bajo coste Aeropuertos Turismo Crecimiento urbanístico Movilidad

Where next for low cost airlines? A spatial and temporal comparative study

The purpose of this paper is to analyze the international development of the low cost airline model. The paper examines and seeks to characterize the factors which have encouraged and inhibited the spatial and temporal spread of low cost carriers. A typology of low cost carriers is developed to illustrate the diversity of practices identifiable under the generic low cost banner. The authors of this paper identify stages of development with respect to time and compare the development of low cost operations in different countries of the world. The economic and political impacts of the spread of the low cost model are examined and the sustainability and future patterns of growth considered.

Pulse-Height Defect of48Ca Ions in an Ion-Implanted Silicon Detector

The results of studying the pulse-height defect (PHD) of 48Ca ions in an ion-implanted silicon detector in the energy range 110 to 223 MeV are presented. The energy dependences of the total PHD, its recombination component, and the relative recombination energy losses are obtained. The dependences of the measured ion energies and PHD on the electric field strength are also obtained. The results are discussed on the basis of a recombination model that takes into consideration the spread of nonequilibrium current carriers due to ambipolar diffusion during the plasma time.

Carrier diffusion in InGaAs/GaAs quantum wells grown on vicinal [formula omitted] substrates

We have investigated the influence of vicinal GaAs substrates on the optical and electronic properties of InGaAs/GaAs quantum wells (QWs). A single In 0.10Ga 0.90As QW was grown by molecular-beam epitaxy on a vicinal GaAs(0 0 1) substrate with a miscut angle of 0° (nominal), 2°, 4° and 6° towards [1 1 0] . The carrier diffusion was obtained by a micro-photoluminescence scan technique that permits to observe the effective diffusion length characterized by the lateral spread of carriers in the QW followed by radiative recombination. The carrier diffusion length was obtained parallel ( L ||) and perpendicular ( L ⊥) to the atomic steps. The diffusion length decreases as the temperature increases up to 100 K . Above this temperature we found different behaviours that depend on the sample miscut angle.

Qualitative theory of the spread of a new gene into a resident population

This work addresses the problems that arise in the estimation of the risk of invader/unwanted GMO spread and the optimal release of desired genes into a population through the release of transgenic individuals. On the basis of a general model of the propagation of an advantageous allele through a population we analyze the thresholds and critical aggregations in gene frequency necessary for the spread of new gene carriers. It is shown that if the invader appears at one place in the ecosystem then it will not spread throughout the ecosystem unless it exceeds some critical threshold, where the critical threshold is defined in terms of both the amount and distribution of the invader. The value of the critical threshold will depend on the fitness of the invader relative to the fitness of the resident organisms in the ecosystem and the mechanism of its dispersion. It is also shown that typically an invader will not spread symmetrically, even if the environment is isotropic, but rather develops clusters that form filaments within the ecosystem. We also demonstrate that if the invader aggregation is sufficiently large then after an initial period the advance of the invader into the resident population takes the form of a traveling wave. The speed of this wave tends to a speed characteristic of the relative fitness and dispersive mechanisms of the invader.

The Characterisation of The Compositional and Electronic Profiles of Delta-Doped Layers Using Transmission Electron Microscopy

AbstractThe compositional profile of an interlayer inferred from Fresnel contrast data is usually determined assuming that the variation in the measured mean forward scattering potential is associated with changes in neutral atom scattering factor and atomic density. However, the technique is currently being applied to systems for which the form and the magnitude of the potential at the layer can be affected strongly by changes in ionicity. Here, we show how the analysis of ‘delta-doped’ layers in semiconductors, which contain thin layers of impurity ions at low concentrations, requires the analysis of not only the effect of strains on the density but also the contribution to the potential from charged ions surrounded by a wider spread of free carriers.

Photostimulated kinetic effects in semiconductors

It is shown that the presence of intense laser radiation can result in the origination of “spreading” of kinetic effects even in a degenerate monopolar semiconductor with an isotropic energy spectrum, where the magnitude of such “photostimulated” effects can exceed the magnitude of corresponding effects in the absence of radiation, due to the thermal spread of current carriers in the energies or anisotropies of isoenergetic surfaces. Photostimulated Ettingshausen, Peltier, and transverse magnetoresistive effects are considered.