Comparing alternatives to the fixed degree sequence model for extracting the backbone of bipartite projections

Projections of bipartite or two-mode networks capture co-occurrences, and are used in diverse fields (e.g., ecology, economics, bibliometrics, politics) to represent unipartite networks. A key challenge in analyzing such networks is determining whether an observed number of co-occurrences between two nodes is significant, and therefore whether an edge exists between them. One approach, the fixed degree sequence model (FDSM), evaluates the significance of an edge’s weight by comparison to a null model in which the degree sequences of the original bipartite network are fixed. Although the FDSM is an intuitive null model, it is computationally expensive because it requires Monte Carlo simulation to estimate each edge’s p value, and therefore is impractical for large projections. In this paper, we explore four potential alternatives to FDSM: fixed fill model, fixed row model, fixed column model, and stochastic degree sequence model (SDSM). We compare these models to FDSM in terms of accuracy, speed, statistical power, similarity, and ability to recover known communities. We find that the computationally-fast SDSM offers a statistically conservative but close approximation of the computationally-impractical FDSM under a wide range of conditions, and that it correctly recovers a known community structure even when the signal is weak. Therefore, although each backbone model may have particular applications, we recommend SDSM for extracting the backbone of bipartite projections when FDSM is impractical.

THE STAMP TECHNIQUE FOR DIRECT COMPOSITE RESTORATIONS

Intoduction: A high level of aestheticscanonlybeachieved by refiningold techniques and introducing new ones. One of the mostrecent techniques is the stamptechnique.Thisis a relatively new methodthat manages to restore the occlusal anatomyalmostperfectly. Althoughitispractical, it has been adopted by only a smallpercentage of practitioners. Methods:This technique wasused on two patients with occlusal caries of differentseverity, whichallowed for an estheticfillingwith a close approximation of the natural dental anatomy. Results:An estheticrestorationwithoutretouching andwithoutoverbiteallowing a hormonal integration in the occlusion. Discussion:This isbecausemanualrestoration in esthetic direct composite is a technique thatrequiresskill and finesse and finishingthatis essential for the longevity of the restoration. With the buffer technique the overall time isreduced and the degree of porosity in the restorationisconsiderablyreduced. The purpose of this article is to clarifythis technique, to discussits limitations and indications as to illustrateitsprotocolthrough a clinical case.

Small intestinal pseudodiverticulosis in a pony mare

A 14-y-old pony mare was referred after 30-d duration of intermittent pyrexia, anorexia, weight loss, and change in manure consistency. Physical examination revealed a palpable but reducible ventral abdominal mass. Transabdominal ultrasonography revealed multiple distended, hypomotile, and thickened small intestinal loops in close approximation with numerous, well-defined, hyperechoic masses. There was a large amount of echogenic peritoneal fluid; abdominocentesis revealed a neutrophilic and macrophagic inflammatory exudate, and a mixed bacterial population was cultured. Given the poor prognosis, the mare was euthanized. The autopsy findings included a large abdominal abscess, serosanguineous peritoneal fluid with fibrin strands, and ~50 outpouches communicating with the lumen and extending from the anti-mesenteric aspect of the duodenum, jejunum, and ileum. These structures were classified as pseudodiverticula based on the histologic absence of the tunica muscularis layer of the intestinal wall. Pseudodiverticula should be included as a differential etiology in horses when clinical signs consistent with colic, diarrhea, or weight loss are recognized and, when on examination, one or more organized masses are palpated or visualized on transabdominal ultrasound, as well as visualization of small intestinal loops with thickened walls.

What is your diagnosis? Labial adhesions – Classification and treatment

An 8-month-old Caucasian female infant with a history of two urinary tract infections presented with fever, poor oral intake, and increased irritability for 3 days prior to presentation. The mother reported a fever T max 103F and a strong odor of urine. Mother denied any cold, cough, diarrhea, vomiting, rash, and sick contacts at home. Her initial vitals were normal other than a temperature of 101F. The infant was alert, active and comfortable in her mother’s lap. On examination of her external genitalia, there was fused labia minora at the midline forming a midline raphe, and pinhole urethral opening was also noted (Figure 1). Due to close approximation of labia minora and tiny urethral opening, we were unbale to catheterize the bladder. According to the mother, previous attempts to catheterize the bladder for urinary samples were never successful as well. We confirmed the labial adhesions as shown in (Figure 1) based on our clinical examination and a presumptive diagnosis of UTI was made based on a positive bag urine sample and her symptoms.

REACT-1 round 10 report: Level prevalence of SARS-CoV-2 swab-positivity in England during third national lockdown in March 2021

BackgroundIn England, hospitalisations and deaths due to SARS-CoV-2 have been falling consistently since January 2021 during the third national lockdown of the COVID-19 pandemic. The first significant relaxation of that lockdown occurred on 8 March when schools reopened.MethodsThe REal-time Assessment of Community Transmission-1 (REACT-1) study augments routine surveillance data for England by measuring swab-positivity for SARS-CoV-2 in the community. The current round, round 10, collected swabs from 11 to 30 March 2021 and is compared here to round 9, in which swabs were collected from 4 to 23 February 2021.ResultsDuring round 10, we estimated an R number of 1.00 (95% confidence interval 0.81, 1.21). Between rounds 9 and 10 we estimated national prevalence has dropped by ∼60% from 0.49% (0.44%, 0.55%) in February to 0.20% (0.17%, 0.23%) in March. There were substantial falls in weighted regional prevalence: in South East from 0.36% (0.29%, 0.44%) in round 9 to 0.07% (0.04%, 0.12%) in round 10; London from 0.60% (0.48%, 0.76%) to 0.16% (0.10%, 0.26%); East of England from 0.47% (0.36%, 0.60%) to 0.15% (0.10%, 0.24%); East Midlands from 0.59% (0.45%, 0.77%) to 0.19% (0.13%, 0.28%); and North West from 0.69% (0.54%, 0.88%) to 0.31% (0.21%, 0.45%). Areas of apparent higher prevalence remain in parts of the North West, and Yorkshire and The Humber. The highest prevalence in March was found among school-aged children 5 to 12 years at 0.41% (0.27%, 0.62%), compared with the lowest in those aged 65 to 74 and 75 and over at 0.09% (0.05%, 0.16%). The close approximation between prevalence of infections and deaths (suitably lagged) is diverging, suggesting that infections may have resulted in fewer hospitalisations and deaths since the start of widespread vaccination.ConclusionWe report a sharp decline in prevalence of infections between February and March 2021. We did not observe an increase in the prevalence of SARS-CoV-2 following the reopening of schools in England, although the decline of prevalence appears to have stopped. Future rounds of REACT-1 will be able to measure the rate of growth or decline from this current plateau and hence help assess the effectiveness of the vaccination roll-out on transmission of the virus as well as the potential size of any third wave during the ensuing months.

Islet sympathetic innervation and islet neuropathology in patients with type 1 diabetes

Dysregulation of glucagon secretion in type 1 diabetes (T1D) involves hypersecretion during postprandial states, but insufficient secretion during hypoglycemia. The sympathetic nervous system regulates glucagon secretion. To investigate islet sympathetic innervation in T1D, sympathetic tyrosine hydroxylase (TH) axons were analyzed in control non-diabetic organ donors, non-diabetic islet autoantibody-positive individuals (AAb), and age-matched persons with T1D. Islet TH axon numbers and density were significantly decreased in AAb compared to T1D with no significant differences observed in exocrine TH axon volume or lengths between groups. TH axons were in close approximation to islet α-cells in T1D individuals with long-standing diabetes. Islet RNA-sequencing and qRT-PCR analyses identified significant alterations in noradrenalin degradation, α-adrenergic signaling, cardiac β-adrenergic signaling, catecholamine biosynthesis, and additional neuropathology pathways. The close approximation of TH axons at islet α-cells supports a model for sympathetic efferent neurons directly regulating glucagon secretion. Sympathetic islet innervation and intrinsic adrenergic signaling pathways could be novel targets for improving glucagon secretion in T1D.

Maximal prime gaps bounds

This paper presents research results, pertinent to the maximal prime gaps bounds. Four distinct bounds are presented: Upper bound, Infimum, Supremum and finally the Lower bound. Although the Upper and Lower bounds incur a relatively high estimation error cost, the functions representing them are quite simple. This ensures, that the computation of those bounds will be straightforward and efficient. The Lower bound is essential, to address the issue of the value of the lower bound implicit constant C, in the work of Ford et al (Ford, 2016). The concluding Corollary in this paper shows, that the value of the constant C does diverge, although very slowly. The constant C, will eventually take any arbitrary value, providing that a large enough N (for p <= N) is considered. The Infimum/Supremum bounds on the other hand are computationally very demanding. Their evaluation entails computations at an extreme level of precision. In return however, we obtain bounds, which provide an extremely close approximation of the maximal prime gaps. The Infimum/Supremum estimation error gradually increases over the range of p and attains at p = 18361375334787046697 approximately the value of 0.03.

TO THE CALCULATION OF LENGTH OF GEOPHYSICAL OBJECTS OF HYPERBOLIC OUTLINE

Hyperbolic curves are used in various theoretical and practical studies, including in the field of water management and environmental construction when calculating various geophysical objects with hyperbolic outlines (surfaces of coastal slopes, sliding lines of landslide massifs, directing dams, spillway surfaces of watersheds, water free fall trajectories, etc.). The exact determination of the length of the hyperbola arc is represented by a rather complex dependence based on “unbreakable” incomplete elliptic integrals, which makes it difficult to carry out analytical calculations and involves the use of tabular data with a time-consuming cross and non-linear interpolation of them, etc. Elementary dependencies are proposed to determine the length of the hyperbola arc, which give a very close approximation (up to 1%) to exact values. The obtained calculated analytical dependencies for determining the length of the hyperbola arc are recommended for practical use in theoretical and applied research in various fi elds of science and technology.

Postcolonial Ecocritical Reading of Death of a River Guide and Gould’s Book of Fish

“Boy’s brother George would lay a piece of wet bark down the side of the logs burning in the fire to allow the ants to escape, and only shot just what was needed for his pot (Death of a River Guide 69).” Animals have always remained in the periphery of the human world and literature. Eco critics have also focused on animals only to some extent. That is mainly because animals are used as human food. The paper is a postcolonial Eco critical reading of Death of a River Guide and Gould’s Book of Fish. Flanagan has given due importance to animals in all his novels. Animals are also part of culture of a nation. Australia has vast variety of Flora and Fauna. Flanagan writes about animals peculiar to Australian mainland. The Australian aborigines have lived in close approximation with animals. When the land was colonized, even animals of the land were affected. The paper aims to fill the gap left by Eco critics by analyzing the relationship between animals, nature and characters of the select novels.