Networks of noisy oscillators with correlated degree and frequency dispersion

We investigate how correlations between the diversity of the connectivity of networks and the dynamics at their nodes affect the macroscopic behavior. In particular, we study the synchronization transition of coupled stochastic phase oscillators that represent the node dynamics. Crucially in our work, the variability in the number of connections of the nodes is correlated with the width of the frequency distribution of the oscillators. By numerical simulations on Erdös-Rényi networks, where the frequencies of the oscillators are Gaussian distributed, we make the counterintuitive observation that an increase in the strength of the correlation is accompanied by an increase in the critical coupling strength for the onset of synchronization. We further observe that the critical coupling can solely depend on the average number of connections or even completely lose its dependence on the network connectivity. Only beyond this state, a weighted mean-field approximation breaks down. If noise is present, the correlations have to be stronger to yield similar observations.

What hurts the dominant airlines at hub airports?

This paper estimates a frequency equation to explain the determinants of network airline service levels at their hub airports. Drawing on European data for 2002 - 2013, we find that network airlines reduce frequencies when the share of low - cost airlines increases both on the route and at the hub airport. On the contrary, frequency choices of network airlines are not affected by competition from low - cost airlines operating in nearby secondary airports. We also find some evidence that mergers in Europe may result in a re - organization of the route structure in favor of the hubs of the larger airline.

What hurts the dominant airlines at hub airports?

This paper estimates a frequency equation to explain the determinants of network airline service levels at their hub airports. Drawing on European data for 2002 - 2013, we find that network airlines reduce frequencies when the share of low - cost airlines increases both on the route and at the hub airport. On the contrary, frequency choices of network airlines are not affected by competition from low - cost airlines operating in nearby secondary airports. We also find some evidence that mergers in Europe may result in a re - organization of the route structure in favor of the hubs of the larger airline.

Air services on thin routes : Regional versus low-cost airlines

An examination of the impact in the US and EU markets of two major innovations in the provision of air services on thin routes - regional jet technology and the low-cost business model - reveals significant differences. In the US, regional airlines monopolize a high proportion of thin routes, whereas low-cost carriers are dominant on these routes in Europe. Our results have different implications for business and leisure travelers, given that regional services provide a higher frequency of flights (at the expense of higher fares), while low-cost services offer lower fares (at the expense of lower flight frequencies).

The genetic content of chromosomal inversions across a wide latitudinal gradient

There is increasing evidence regarding the role of chromosomal inversions in relevant biological processes such as local adaptation and speciation. A classic example of the adaptive role of chromosomal polymorphisms is given by the clines of inversion frequencies in Drosophila subobscura, repeatable across continents. Nevertheless, not much is known about the molecular variation associated with these polymorphisms. We characterized the genetic content of ca. 600 individuals from nine European populations following a latitudinal gradient by analysing 19 microsatellite loci from two autosomes (J and U) and the sex chromosome (A), taking into account their chromosomal inversions. Our results clearly demonstrate the molecular genetic uniformity within a given chromosomal inversion across a large latitudinal gradient, particularly from Groningen (Netherlands) in the north to Málaga (Spain) in the south, experiencing highly diverse environmental conditions. This low genetic differentiation within the same gene arrangement across the nine European populations is consistent with the local adaptation hypothesis for th evolutionof chromosomal polymorphisms. We also show the effective role of chromosomal inversions in maintaining different genetic pools within these inverted genomic regions even in the presence of high gene flow. Inversions represent thus an important barrier to gene flux and can help maintain specific allelic combinations with positive effects on fitness. Consistent patterns of microsatellite allele-inversion linkage disequilibrium particularly in loci within inversions were also observed. Finally, we identified areas within inversions presenting clinal variation that might be under selection.

Traditional cockney and popular London speech

This paper gives a full description of the phonetics and phonology of Traditional Cockney and Popular London speech, treating these varieties as constituting a continuum rather than two separate dialects. Exemplification of the vowels, diphthongs and consonants is provided, both in isolate words and in connected speech, along with their range of variation. The frequencies of the vowels have been charted on the basis of the pronunciation of three elderly male speakers. Regarding the consonants, there are detailed observations on the features typically associated with the linguistic varieties examined: strong aspiration of unvoiced plosives, glottalization, H-dropping, L-vocalization and TH-fronting. A section on prosody provides coverage of lexical stress, rhythm and intonation. The paper takes into account up-to-date research on these phenomena, but does not deal with the most recent vowel shifts, some of which form part of Multi-cultural London English.

The whereabouts of an ancient wonderer: Global phylogeography of the solitary ascidian Styela plicata

Genetic tools have greatly aided in tracing the sources and colonization history of introduced species. However, recurrent introductions and repeated shuffling of populations may have blurred some of the genetic signals left by ancient introductions. Styela plicata is a solitary ascidian distributed worldwide. Although its origin remains unclear, this species is believed to have spread worldwide by travelling on ship's hulls. The goals of this study were to infer the genetic structure and global phylogeography of S. plicata and to look for present-day and historical genetic patterns. Two genetic markers were used: a fragment of the mitochondrial gene Cytochrome Oxidase subunit I (COI) and a fragment of the nuclear gene Adenine Nucleotide Transporter/ADP-ATP Translocase (ANT). A total of 368 individuals for COI and 315 for ANT were sequenced from 17 locations worldwide. The levels of gene diversity were moderate for COI to high for ANT. The Mediterranean populations showed the least diversity and allelic richness for both markers, while the Indian, Atlantic and Pacific Oceans had the highest gene and nucleotide diversities. Network and phylogenetic analyses with COI and ANT revealed two groups of alleles separated by 15 and 4 mutational steps, respectively. The existence of different lineages suggested an ancient population split. However, the geographic distributions of these groups did not show any consistent pattern, indicating different phylogeographic histories for each gene. Genetic divergence was significant for many population-pairs irrespective of the geographic distance among them. Stochastic introduction events are reflected in the uneven distribution of COI and ANT allele frequencies and groups among many populations. Our results confirmed that S. plicata has been present in all studied oceans for a long time, and that recurrent colonization events and occasional shuffling among populations have determined the actual genetic structure of this species.

Contribution of cytochrome P450 and ABCB1 genetic variability on methadone pharmacokinetics, dose requirements, and response

Although the efficacy of methadone maintenance treatment (MMT) in opioid dependence disorder has been well established, the influence of methadone pharmacokinetics in dose requirement and clinical outcome remains controversial. The aim of this study is to analyze methadone dosage in responder and nonresponder patients considering pharmacogenetic and pharmacokinetic factors that may contribute to dosage adequacy. Opioid dependence patients (meeting Diagnostic and Statistical Manual of Mental Disorders, [4th Edition] criteria) from a MMT community program were recruited. Patients were clinically assessed and blood samples were obtained to determine plasma concentrations of (R,S)-, (R) and (S)- methadone and to study allelic variants of genes encoding CYP3A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, and P-glycoprotein. Responders and nonresponders were defined by illicit opioid consumption detected in random urinalysis. The final sample consisted in 105 opioid dependent patients of Caucasian origin. Responder patients received higher doses of methadone and have been included into treatment for a longer period. No differences were found in terms of genotype frequencies between groups. Only CYP2D6 metabolizing phenotype differences were found in outcome status, methadone dose requirements, and plasma concentrations, being higher in the ultrarapid metabolizers. No other differences were found between phenotype and responder status, methadone dose requirements, neither in methadone plasma concentrations. Pharmacokinetic factors could explain some but not all differences in MMT outcome and methadone dose requirements.

Calculation of radio electrical coverage in Medium-Wave Frequencies

The aim of this project is to accomplish an application software based on Matlab to calculate the radioelectrical coverage by surface wave of broadcast radiostations in the band of Medium Wave (WM) all around the world. Also, given the location of a transmitting and a receiving station, the software should be able to calculate the electric field that the receiver should receive at that specific site. In case of several transmitters, the program should search for the existence of Inter-Symbol Interference, and calculate the field strenght accordingly. The application should ask for the configuration parameters of the transmitter radiostation within a Graphical User Interface (GUI), and bring back the resulting coverage above a map of the area under study. For the development of this project, it has been used several conductivity databases of different countries, and a high-resolution elevation database (GLOBE). Also, to calculate the field strenght due to groundwave propagation, it has been used ITU GRWAVE program, which must be integrated into a Matlab interface to be used by the application developed.

Frequencies of DEA blood types in a purebred canine blood donor population in Porto Alegre, RS, Brazil

The study of canine immunohematology is very important for veterinary transfusion medicine. The objective of this study was to determine the DEA blood type frequencies in a purebred canine blood donor population from Porto Alegre, RS, Brazil. One hundred clinically healthy purebred dogs were chosen, 20 dogs from each breed (Great Dane, Rottweiler, Golden Retriever, German Shepherd and Argentine Dogo). Blood samples were taken in ACD-A tubes and the MSU hemagglutination tube test (MI, USA) was used to determine the blood types. The studied population presented general frequencies of 61% for DEA 1.1, 22% for DEA 1.2, 7% for DEA 3, 100% for DEA 4, 9% for DEA 5 and 16% for DEA 7. A significant association was found between breeds and certain combinations of blood types in this population. The results are in agreement with the literature since most part of the canine population studied was positive for DEA 1.1, the most antigenic blood type in dogs. Differences were found among the studied breeds and those should be considered when selecting a blood donor. The knowledge of blood types frequencies and their combinations in different canine populations, including different breeds, is important because it shows the particularities of each group, helps to keep a data bank of local frequencies and minimizes the risks of transfusion reactions.

k-Casein gene frequencies support subdivision and historical origin of Argentine Creole cattle

Gene frequencies at the k-casein locus were estimated in six different herds (N = 180) of Argentinean Creole cattle. The results showed a strong influence of subdivision and independent evolution on the divergence of the observed gene frequencies. These results suggest that the population structure of these herds favor the maintenance of polymorphism, which is of crucial importance for the long-time survival of populations.

Effects of L-arginine on the diaphragm muscle twitches elicited at different frequencies of nerve stimulation

In rats, the nitric oxide (NO)-synthase pathway is present in skeletal muscle, vascular smooth muscle, and motor nerve terminals. Effects of NO were previously studied in rat neuromuscular preparations receiving low (0.2 Hz) or high (200 Hz) frequencies of stimulation. The latter frequency has always induced tetanic fade. However, in these previous studies we did not determine whether NO facilitates or impairs the neuromuscular transmission in preparations indirectly stimulated at frequencies which facilitate neuromuscular transmission. Thus, the present study was carried out to examine the effects of NO in rat neuromuscular preparations indirectly stimulated at 5 and 50 Hz. The amplitude of muscular contraction observed at the end (B) of a 10-s stimulation was taken as the ratio (R) of that obtained at the start (A) (R = B/A). S-nitroso-N-acetylpenicillamine (200 µM), superoxide dismutase (78 U/ml) and L-arginine (4.7 mM), but not D-arginine (4.7-9.4 mM), produced an increase in R (facilitation of neurotransmission) at 5 Hz. However, reduction in the R value (fade of transmission) was observed at 50 Hz. N G-nitro-L-arginine (8.0 mM) antagonized both the facilitatory and inhibitory effects of L-arginine (4.7 mM). The results suggest that NO may modulate the release of acetylcholine by motor nerve terminals.

Allelic frequencies of six polymorphic markers for risk of prostate cancer

The aim of the present study was to evaluate the distribution of polymorphisms for the androgen receptor (AR) (CAG, StuI, GGN), SRD5A2 (Ala49Thr, Val89Leu) and CYP17 (MspA1) genes that are considered to be relevant for risk of prostate cancer. We studied 200 individuals from two cities in the State of São Paulo, by PCR, PCR-RFLP and ASOH techniques. The allelic frequencies of the autosomal markers and the StuI polymorphism of the AR gene were very similar to those described in most North American and European populations. In relation to the CAG and GGN number of repeats, the study subjects had smaller repeat lengths (mean of 20.65 and 22.38, respectively) than those described in North American, European and Chinese populations. In the present study, 30.5% of the individuals had less than 22 CAG repeats and 45.5% had less than 23 GGN repeats. When both repeat lengths are considered jointly, this Brazilian population is remarkably different from the others. Further studies on prostate cancer patients need to be conducted to assess the significance of these markers in the Brazilian population.

Contrast sensitivity to radial frequencies modulated by Jn and j n Bessel profiles

We measured human contrast sensitivity to radial frequencies modulated by cylindrical (Jo) and spherical (j o) Bessel profiles. We also measured responses to profiles of j o, j1, j2, j4, j8, and j16. Functions were measured three times by at least three of eight observers using a forced-choice method. The results conform to our expectations that sensitivity would be higher for cylindrical profiles. We also observed that contrast sensitivity is increased with the j n order for n greater than zero, having distinct orderly effects at the low and high frequency ends. For n = 0, 1, 2, and 4 sensitivity tended to occur around 0.8-1.0 cpd while for n = 8 and 16 it seemed to shift gradually to 0.8-3.0 cpd. We interpret these results as being consistent with the possibility that spatial frequency processing by the human visual system can be defined a priori in terms of polar coordinates and discuss its application to study face perception.