•Methods for estimating ERGMs are centered around approximations.•Modern computers make it feasible to compute the ERGM support for small networks.•We wrote an R package (ergmito) that fits ERGMs for ...pooled models using MLE.•“Exact” methods can make big practical and inferential improvements.•Using “exact” methods opens a window for innovations in the little networks field.
Statistical models for social networks have enabled researchers to study complex social phenomena that give rise to observed patterns of relationships among social actors and to gain a rich understanding of the interdependent nature of social ties and actors. Much of this research has focused on social networks within medium to large social groups. To date, these advances in statistical models for social networks, and in particular, of Exponential-Family Random Graph Models (ERGMS), have rarely been applied to the study of small networks, despite small network data in teams, families, and personal networks being common in many fields. In this paper, we revisit the estimation of ERGMs for small networks and propose using exhaustive enumeration when possible. We developed an R package that implements the estimation of pooled ERGMs for small networks using Maximum Likelihood Estimation (MLE), called “ergmito”. Based on the results of an extensive simulation study to assess the properties of the MLE estimator, we conclude that there are several benefits of direct MLE estimation compared to approximate methods and that this creates opportunities for valuable methodological innovations that can be applied to modeling social networks with ERGMs.
Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical landscape may be altered by the ...invasion of exotic insect species. The spotted-wing drosophila (SWD),
Drosophila suzukii
(Diptera: Drosophilidae), is a highly polyphagous fruit pest native to eastern Asia and recently arrived in South America. Our study aimed to characterize the effect of SWD attack on the volatile organic compounds (VOCs) of blueberries, a common host fruit, and to correlate these odor changes with the olfactory-mediated behavioral response of resident populations of
Trichopria anastrephae
parasitoids, here reported for the first time in Uruguay. Using fruit VOC chemical characterization followed by multivariate analyses of the odor blends of blueberries attacked by SWD, we showed that the development of SWD immature stages inside the fruit generates a different odor profile to that from control fruits (physically damaged and free of damage). These differences can be explained by the diversity, frequency, and amounts of fruit VOCs. The behavioral response of
T. anastrephae
in Y-tube bioassays showed that female wasps were significantly attracted to volatiles from SWD-attacked blueberries when tested against both clean air and undamaged blueberries. Therefore,
T. anastrephae
females can use chemical cues from SWD-infested fruits, which may lead to a successful location of their insect host. Since resident parasitoids are able to locate this novel potential host, biological control programs using local populations may be plausible as a strategy for control of SWD.
We propose UV-completions of Froggatt–Nielsen–Peccei–Quinn models of fermion masses and mixings with flavored axions, by incorporating heavy fields. Here, the
U
(1) Froggatt–Nielsen symmetry is ...identified with the Peccei–Quinn symmetry to solve the strong CP problem along with the mass hierarchies of the Standard Model fermions. We take into account leading order contributions to the fermion mass matrices giving rise to Nearest-Neighbour-Interaction structure in the quark sector and
A
2
texture in the neutrino sector. A comprehensive numerical analysis has been performed for the fermion mass matrices. Subsequently, we investigate the resulting axion flavor violating couplings and the axion-photon coupling arising from the model.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study uses recent data to investigate if smoking initiation diffuses through friendship networks over the high school period and explores if diffusion processes differ across schools. One ...thousand four hundred and twenty-five racially and ethnically diverse youth from four high schools in Los Angeles were surveyed four times over the high school period from 2010 to 2013. Probit regression models and stochastic actorbased models for network dynamics tested for peer effects on smoking initiation. Friend smoking was found to predict adolescent smoking, and smoking initiation diffused through friendship networks in some but not all of the schools. School differences in smoking rates and the popularity of smokers may be linked to differences in the diffusion of smoking through peer networks. We conclude that there are differences in peer effects on smoking initiation across schools that will be important to account for in network-based smoking interventions.
A
bstract
We explore the possibility of having a fermionic dark matter candidate within U(1)′ models for CE
ν
NS experiments in light of the latest COHERENT data and the current and future dark ...matter direct detection experiments. A vector-like fermionic dark matter has been introduced which is charged under U(1)′ symmetry, naturally stable after spontaneous symmetry breaking. We perform a complementary investigation using CE
ν
NS experiments and dark matter direct detection searches to explore dark matter as well as
Z
′ boson parameter space. Depending on numerous other constraints arising from the beam dump, LHCb, BABAR, and the forthcoming reactor experiment proposed by the SBC collaboration, we explore the allowed region of
Z
′ portal dark matter.
Drosophila suzukii
(Diptera: Drosophilidae) is a highly polyphagous fruit pest native to eastern Asia, which in the last decade had widely expanded its range and become a serious pest in the Americas ...and Europe. Invasion routes and the genetic diversity in populations of South America are poorly studied. Here, we compared the patterns of genetic variation of native populations and previously invaded regions (in America and Europe) with the genetic diversity of the recent invasion in Argentina. In addition, we explored the regional trade routes and volume of host fruits (Argentina, Brazil, Chile and Uruguay) to understand propagule pressure. We report for the first time a genetic assessment of the invasion history of
D. suzukii
in Argentina, noting genetic diversity at
Cytochrome c oxidase subunit I gene fragment
comparable with other recently colonized countries. In the years prior to the invasion into South America, Brazil imported large quantities of potential host fruits from different countries that had been previously invaded; likely Brazil might be the main source of
D. suzukii
in Argentina. This is emphasized by the fact that Argentina and Brazil share haplotypes; however, direct commercial pathway with the USA cannot be discarded, and additional sources of species arrivals are also possible. Our results suggest at least two invasion events could have occurred in Argentina, originating both from previously invaded areas (i.e., North America and Brazil). Our study provides information to improve our understanding of the routes and factors affecting the invasion of this economically significant pest in South America.
Identifying effective drugs for Coronavirus disease 2019 (COVID-19) is urgently needed. An efficient approach is to evaluate whether existing approved drugs have anti-SARS-CoV-2 effects. The ...antiviral properties of lithium salts have been studied for many years. Their anti-inflammatory and immune-potentiating effects result from the inhibition of glycogen synthase kinase-3.
To obtain pre-clinical evidence on the safety and therapeutic effects of lithium salts in the treatment of COVID-19.
Six different concentrations of lithium, ranging 2–12 mmol/L, were evaluated. Lithium inhibited the replication of SARS-CoV-2 virus in a dose-dependent manner with an IC50 value of 4 mmol/L. Lithium-treated wells showed a significantly higher percentage of monolayer conservation than viral control, particularly at concentrations higher than 6 mmol/L, verified through microscopic observation, the neutral red assay, and the determination of N protein in the supernatants of treated wells. Hamsters treated with lithium showed less intense disease with fewer signs. No lithium-related mortality or overt signs of toxicity were observed during the experiment. A trend of decreasing viral load in nasopharyngeal swabs and lungs was observed in treated hamsters compared to controls.
These results provide pre-clinical evidence of the antiviral and immunotherapeutic effects of lithium against SARS-CoV-2, which supports an advance to clinical trials on COVID-19′s patients.
Display omitted
•Antiviral, anti-inflammatory and immune-potentiating effects of lithium salts have been described.•Lithium directly inhibits the replication of SARS-CoV-2 in Vero E6 cells in a concentration-dependent manner with an IC50 of 4 mmol/L.•Syrian hamsters treated with human therapeutic doses of lithium showed a less intense disease.
A
bstract
New light gauge bosons can affect several low-energy experiments, such as atomic parity violation or colliders. Here, we explore the possibility that a dark sector is charged under a new ...U(1) gauge symmetry, and the portal to the Standard Model is through a
Z
−
Z
′ mass mixing. In our approach, breaking the new gauge symmetry is crucial to generate neutrino masses. We investigate the parameter space to reproduce neutrino masses, the correct dark matter relic abundance, and to produce the observed core-like DM distribution in galactic centers.
Combining a macrolide or a fluoroquinolone to beta-lactam regimens in the treatment of patients with moderate to severe community-acquired pneumonia is recommended by the international guidelines. ...However, the information in patients with bacteraemic pneumococcal pneumonia is limited.
A propensity score technique was used to analyze prospectively collected data from all patients with bacteraemic pneumococcal pneumonia admitted from 2000 to 2015 in our institution, who had received empirical treatment with third-generation cephalosporin in monotherapy or plus macrolide or fluoroquinolone.
We included 69 patients in the monotherapy group and 314 in the combination group. After adjustment by PS for receiving monotherapy, 30-day mortality (OR 2.89; 95% CI 1.07–7.84) was significantly higher in monotherapy group. A higher 30-day mortality was observed in monotherapy group in both 1:1 and 1:2 matched samples although it was statistically significant only in 1:2 sample (OR: 3.50 (95% CI 1.03–11.96), P = 0.046).
Our study suggests that in bacteraemic pneumococcal pneumonia, empirical therapy with a third-generation cephalosporin plus a macrolide or a fluoroquinolone is associated with a lower mortality rate than beta-lactams in monotherapy. These results support the recommendation of combination therapy in patients requiring admission with moderate to severe disease.
PDF
