bluuebunny/crossref_metadata_2025 huggingface dataset:
BOLD quantified renal pO2 is sensitive to pharmacological challenges in rats
Authors: Thacker Jon , Zhang Jeff L. , Franklin Tammy , Prasad Pottumarthi
Published: August 2016

Purpose

Blood oxygen level‐dependent (BOLD) MRI has been effectively used to monitor changes in renal oxygenation. However, R2* (or T2*) is not specific to blood oxygenation and is dependent on other factors. This study investigates the use of a statistical model that takes these factors into account and maps BOLD MRI measurements to blood pO2.

Methods

Spin echo and gradient echo images were obtained in six Sprague‐Dawley rats and R2 and R2* maps were computed. Measurements were made at baseline, post‐nitric oxide synthase inhibitor (L‐NAME), and post‐furosemide administration. A simulation of each region was performed to map R2′ (computed as R2*–R2) to blood pO2.

Results

At baseline, blood pO2 in the outer medulla was 30.5 ± 1.2 mmHg and 51.9 ± 5.2 mmHg in the cortex, in agreement with previous invasive studies. Blood pO2 was found to decrease within the outer medulla following L‐NAME (P < 0.05) and increase after furosemide (P < 0.05). Blood pO2 in the cortex increased following furosemide (P < 0.05).

Conclusions

Model‐derived blood pO2 is sensitive to pharmacological challenges, and baseline pO2 is comparable to literature values. Reporting pO2 instead of R2* could lead to a greater clinical impact of renal BOLD MRI and facilitate the identification of hypoxic regions. Magn Reson Med 78:297–302, 2017. © 2016 International Society for Magnetic Resonance in Medicine
Resequencing with parallel queues to minimize the maximum number of items in the overflow area
Authors: Boywitz David , Boysen Nils , Briskorn Dirk
Published: August 2016

This article treats an elementary optimization problem, where an inbound stream of successive items is to be resequenced with the help of multiple parallel queues in order to restore an intended target sequence. Whenever early items block the one item to be currently released into the target sequence, they are withdrawn from their queue and intermediately stored in an overflow area until their actual release is reached. We aim to minimize the maximum number of items simultaneously stored in the overflow area during the complete resequencing process. We met this problem in industry practice at a large German automobile producer, who has to resequence containers with car seats prior to the assembly process. We formalize the resulting resequencing problem and provide suited exact and heuristic solution algorithms. In our computational study, we also address managerial aspects such as how to properly avoid the negative effects of sequence alterations. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 401–415, 2016
Minimal disconnected cuts in planar graphs
Authors: Kamiński Marcin , Paulusma Daniël , Stewart Anthony , Thilikos Dimitrios M.
Published: August 2016

The problem of finding a disconnected cut in a graph is NP‐hard in general but polynomial‐time solvable on planar graphs. The problem of finding a minimal disconnected cut is also NP‐hard but its computational complexity was not known for planar graphs. We show that it is polynomial‐time solvable on 3‐connected planar graphs but NP‐hard for 2‐connected planar graphs. Our technique for the first result is based on a structural characterization of minimal disconnected cuts in 3‐connected
‐free‐minor graphs and on solving a topological minor problem in the dual. In addition we show that the problem of finding a minimal connected cut of size at least 3 is NP‐hard for 2‐connected apex graphs. Finally, we relax the notion of minimality and prove that the problem of finding a so‐called semi‐minimal disconnected cut is still polynomial‐time solvable on planar graphs. © 2016 Wiley Periodicals, Inc. NETWORKS, Vol. 68(4), 250–259 2016
Population pharmacokinetic and pharmacodynamic analyses of safinamide in subjects with Parkinson's disease
Authors: Loprete Luca , Leuratti Chiara , Cattaneo Carlo , Thapar Mita M. , Farrell Colm , Sardina Marco
Published: August 2016

Safinamide is an orally administered α‐aminoamide derivative with both dopaminergic and non‐dopaminergic properties. Nonlinear mixed effects models for population pharmacokinetic (PK) and pharmacokinetic–pharmacodynamic (PKPD) analyses were developed using records from, respectively, 623 and 668 patients belonging to two Phase 3, randomized, placebo‐controlled, double‐blind efficacy studies. The aim was to estimate safinamide population PK parameters in patients with Parkinson's disease (PD) on stable levodopa therapy, and to develop a model of safinamide effect on the PD phase of normal functioning (ON‐time). The final models were internally evaluated using visual predictive checks (VPCs), prediction corrected‐VPC, and nonparametric bootstrap analysis. Safinamide profiles were adequately described by a linear one‐compartmental model with first‐order absorption and elimination. CL/F, Vd/F, and KA (95% confidence interval [CI]) were 4.96 (4.73–5.21) L/h, 166 (158–174) L, and 0.582 (0.335–0.829) h−1, respectively. CL/F and Vd/F increased with body weight, while age, gender, renal function, and exposure to levodopa did not influence safinamide PK. The observed ON‐time values were adequately described by a linear model, with time in the study period as dependent variable, and rate of ON‐time change and baseline plus offset effect as slope and intercept parameters. Safinamide treatment resulted in an increase in ON‐time of 0.73 h (week 4), with further ON‐time increase with the same slope as placebo. The increase was not influenced by age, levodopa, or safinamide exposure. The population models adequately describe the population PK of safinamide and safinamide effect on ON‐time. No dose adjustments in elderly and mild to moderate renally impaired patients are requested.
Characterizing the Developmental Trajectory of Sirolimus Clearance in Neonates and Infants
Authors: Emoto C , Fukuda T , Mizuno T , Schniedewind B , Christians Uwe , Adams DM , Vinks AA
Published: August 2016

Sirolimus is increasingly being used in neonates and infants, but the mechanistic basis of age‐dependent changes in sirolimus disposition has not been fully addressed yet. In order to characterize the age‐dependent changes, serial sirolimus clearance (CL) estimates in individual young pediatric patients were collected and analyzed by population modeling analysis. In addition, sirolimus metabolite formation was also investigated to further substantiate the corresponding age‐dependent change in CYP3A activity. The increasing pattern over time of allometrically size‐normalized sirolimus CL estimates vs. age was well described by a sigmoidal Emax model. This age‐dependent increase was also observed within each individual patient over a 4‐year study period. CYP3A‐dependent sirolimus metabolite formation changed in a similar fashion. This study clearly demonstrates the rapid increase of sirolimus CL over time in neonates and infants, indicating the developmental change. This developmental pattern can be explained by a parallel increase in CYP3A metabolic activity.
Approximation schemes for the study of multi‐band Gutzwiller wave functions
Authors: Bünemann Jörg , Linneweber Thorben , Gebhard Florian
Published: August 2016

The minimum of the Gutzwiller energy functional depends on the number of parameters considered in the variational state. For a three‐orbital Hubbard model, we find that the frequently used diagonal Ansatz is very accurate in high‐symmetry situations. For lower symmetry, induced by a crystal‐field splitting or the spin–orbit coupling, the discrepancies in energy between the most general and a diagonal Gutzwiller Ansatz can be quite significant. We discuss approximate schemes that may be employed in multi‐band cases where a minimization of the general Gutzwiller energy functional is too demanding numerically.
The Effects of State Merit Aid Programs on Attendance at Elite Colleges
Authors: Sjoquist David L. , Winters John V.
Published: August 2016

State merit aid programs have been found to reduce the likelihood that students attend college out of state. Using the U.S. News & World Report (USNWR) rankings of colleges and universities to measure college quality and Integrated Postsecondary Education Data System data to measure enrollment, we explore how this reduction in out‐of‐state enrollment differs by the academic quality of the institution. Our difference‐in‐differences results suggest that state merit aid programs do not induce students to forgo attending top 15 ranked schools. However, state merit aid does induce some students to forgo attending out‐of‐state schools ranked below the top 15 and shifts them toward lower quality in‐state schools, so that the net effect is a reduction in academic quality, as measured by USNWR. These effects may have long‐term implications for students' degree completion rates and labor market earnings.
Mechanistic Insights and Computational Design of Transition‐Metal Catalysts for Hydrogenation and Dehydrogenation Reactions
Authors: Chen Xiangyang , Yang Xinzheng
Published: August 2016

Catalytic hydrogenation and dehydrogenation reactions are fundamentally important in chemical synthesis and industrial processes, as well as potential applications in the storage and conversion of renewable energy. Modern computational quantum chemistry has already become a powerful tool in understanding the structures and properties of compounds and elucidating mechanistic insights of chemical reactions, and therefore, holds great promise in the design of new catalysts. Herein, we review our computational studies on the catalytic hydrogenation of carbon dioxide and small organic carbonyl compounds, and on the dehydrogenation of amine–borane and alcohols with an emphasis on elucidating reaction mechanisms and predicting new catalytic reactions, and in return provide some general ideas for the design of high‐efficiency, low‐cost transition‐metal complexes for hydrogenation and dehydrogenation reactions.
Development of Nickel Hydrosilylation Catalysts
Authors: Nakajima Yumiko , Sato Kazuhiko , Shimada Shigeru
Published: August 2016

In this account, our studies on nickel‐catalyzed hydrosilylation reactions are described. A series of (salicylaldiminato)methylnickel complexes efficiently catalyze alkene hydrosilylation under ambient reaction conditions. Commercially available Ni(II) salts, Ni(acac)2(acac = acetylacetonato) and its derivatives bis(hexafluoroacetylacetonato)nickel(II) and bis (2,2,6,6‐tetramethyl‐3,5‐heptanedionato)nickel(II), also act as versatile hydrosilylation catalyst precursors in the presence of NaBHEt3. These systems catalyze the hydrosilylation of various alkenes such as industrially important siloxy‐, amino‐, and epoxy‐substituted ones. The arene‐supported cationic nickel allyl complexes also serve as good catalysts for alkene hydrosilylation at room temperature. These nickel complexes exhibit high selectivity towards the reaction using secondary hydrosilanes. Mechanistic studies based on experiments and DFT calculations support a novel mechanism, which includes a facile Si–H bond cleavage and a Si–C bond formation, assisted by the cooperative action of the allyl ligand.

image
Fluorophore‐binding RNA aptamers and their applications
Authors: Dolgosheina Elena V. , Unrau Peter J.
Published: August 2016

Why image RNA? Of all the biological molecules, RNA exhibits the most diverse range of functions. Evidence suggests that transcription produces a wide range of noncoding RNAs (ncRNAs), both short (e.g., siRNAs, miRNAs) and long (e.g., telomeric RNAs) that regulate many aspects of gene expression, including the epigenetic processes that underlie cell fate determination, polarization, and morphogenesis. All these functions are realized through the exquisite temporal and spatial control of RNA expression levels and the stability of specific RNAs within well‐defined sub‐cellular compartments. Given the central importance of RNA in dictating cell behavior via gene‐related functions, there is a great demand for RNA imaging methods so as to determine the composition of the cellular ‘transcriptome’ and to acquire a complete spatial‐temporal profile of RNA localization. Recent advances in fluorophore‐binding RNA aptamers promise to provide exactly this knowledge, which can ultimately advance our understanding of cell function and behavior in conditions of health and disease, and in response to external stimuli. WIREs RNA 2016, 7:843–851. doi: 10.1002/wrna.1383

This article is categorized under:

RNA Interactions with Proteins and Other Molecules > Small Molecule–RNA Interactions

RNA Methods > RNA Analyses In Vitro and In Silico

RNA Methods > RNA Analyses in Cells
The Role of Troponin in Blunt Cardiac Injury After Multiple Trauma in Humans
Authors: Kalbitz Miriam , Pressmar Jochen , Stecher Johanna , Weber Birte , Weiss Manfred , Schwarz Stephan , Miltner Erich , Gebhard Florian , Huber‐Lang Markus
Published: August 2016

Background

The incidence of cardiac injury in immediate fatalities after blunt trauma remains underestimated, and reliable diagnostic strategies are still missing. Furthermore, clinical data concerning heart‐specific troponin serum levels, injury severity score (ISS), catecholamine treatment and survival of patients on admission to the hospital have rarely been interrelated so far. Therefore, the object of the present study was to identify predictive parameters for mortality in the context of blunt cardiac injury.

Methods

This retrospective observational study included 173 severely injured patients with an ISS ≥25 admitted to the University Hospital of Ulm, a level 1 trauma center, during 2009–2013. Furthermore, 83 blunt trauma victims who died before hospital admission were subjected to postmortem examination at the Institute of Legal Medicine, University of Ulm, during 2009–2014. ISS, cardiac injury and associated thoracic injuries were determined in both groups. Furthermore, in the hospitalized patients, serum troponin and IL‐6 levels were measured.

Results

Macroscopic heart injury was observed in 18 % of the patients who died at the scene and only in 1 % of the patients admitted to the hospital, indicating that macroscopic heart injury is associated with an immediate life‐threatening condition. Troponin levels were elevated in 43 % of the patients after admission to the hospital. Moreover, troponin serum concentrations were significantly higher in patients treated with norepinephrine (26.4 ± 4 ng/l) and in non‐survivors (84.9 ± 22.8 ng/l) compared to patients without catecholamines and survivors, respectively.

Conclusions

Macroscopic heart injury was 20 times more frequent in non‐survivors than in survivors. Serum troponin levels correlated with mortality after multiple injury and therefore may represent a valuable prognostic marker in trauma patients.
On the instability of vortex–wave interaction states
Authors: Deguchi Kengo , Hall Philip
Published: August 2016

In recent years it has been established that vortex–wave interaction theory forms an asymptotic framework to describe high Reynolds number coherent structures in shear flows. Comparisons between the asymptotic approach and finite Reynolds number computations of equilibrium states from the full Navier–Stokes equations have suggested that the asymptotic approach is extremely accurate even at quite low Reynolds numbers. However, unlike the situation with an approach based on solving the full Navier–Stokes equations numerically, the vortex–wave interaction approach has not yet been developed to study the instability of the structures it describes. In this work, a comprehensive study of the different instabilities of vortex–wave interaction states is given and it is shown that there are three different time scales on which instabilities can develop. The most dangerous type is a rapidly growing Rayleigh instability of the streak part of the flow. The least dangerous type is a slow mode operating on the diffusion time scale of the roll–streak part of the flow. The third mode of instability, which we will refer to as the edge mode of instability, occurs on a time scale midway between those of the other two modes. The existence of the latter mode explains why some exact coherent structures can act as edge states between the laminar and turbulent attractors. These stability results are compared to results from Navier–Stokes calculations.
Self-oriented forgiveness and other-oriented forgiveness: Shaping high-quality exchange relationships
Authors: Thompson Bryant , Simkins Travis J
Published: August 2016

We examine the effects of two distinct forgiveness motives, self-oriented and other-oriented, on relationship quality within supervisor–subordinate relationships. We provide empirical evidence that both forgiveness motives are positively associated with leader–member exchange and differentially associated with interpersonal citizenship behavior and suggest that previous forgiveness research may be incomplete. We demonstrate that high-quality leader–member relationships and interpersonal citizenship behavior can be enhanced by self-oriented forgiveness motive and other-oriented forgiveness motive. We further show that the association between forgiveness motive and leader–member exchange can be strengthened by one’s disposition, such that proactive personality strengthens the influence of self-oriented forgiveness motive on leader–member exchange and empathic concern strengthens the influence of other-oriented forgiveness motive on leader–member exchange. This manuscript aims to empirically examine two key pathways to forgiveness: one driven by self-orientation and the other driven by other-orientation.
New inflammatory parameters in laryngopharyngeal reflux
Authors: Arslan H , Çandar T , Kuran S , Akmansu Ş H , Kocatürk S
Published: August 2016

Objectives:

To investigate new inflammatory markers in patients with laryngopharyngeal reflux and determine whether these inflammatory parameters change in response to laryngopharyngeal reflux treatment.

Methods:

Complete blood count was evaluated to obtain platelet count and mean platelet volume and calculate neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio. Laryngopharyngeal reflux patients underwent three-month lansoprazole treatment.

Results:

The study included 45 laryngopharyngeal reflux patients (9 men (20 per cent); mean age, 37.4 ± 11.6 years) and 35 healthy age- and sex-matched controls (7 men (20 per cent); mean age, 38.6 ± 8.9 years). The study group had significantly higher platelet-to-lymphocyte ratios and lower mean platelet volumes than the control group (p = 0.004 and p = 0.047, respectively). There was a significant correlation between platelet-to-lymphocyte ratios and initial inflammatory symptoms (reflux symptom index, p = 0.025; reflux finding score, p = 0.013). There was also a significant correlation between mean platelet volume increase and symptom resolution in the first and third months of treatment (p = 0.04 and p = 0.03, respectively).

Conclusion:

Platelet-to-lymphocyte ratio, a new inflammatory marker of chronic inflammation, was significantly higher in laryngopharyngeal reflux patients. Moreover, these patients had significantly lower mean platelet volume values, which increased with post-treatment symptom improvement.
Mob rulers and part-time cleaners: two reef fish associations at the isolated Ascension Island
Authors: Morais R.A. , Brown J. , Bedard S. , Ferreira C.E.L. , Floeter S.R. , Quimbayo J.P. , Rocha L.A. , Sazima I.
Published: August 2016

Isolated oceanic islands may give rise not only to new and endemic species, but also to unique behaviours and species interactions. Multi-species fish interactions, such as cleaning, following, mob-feeding and others are understudied in these ecosystems. Here we present qualitative and quantitative observations on cleaning and mob-feeding reef fish associations at the isolated Ascension Island, South Atlantic Ocean. Cleaning interactions were dominated by juveniles of the facultative fish cleanersBodianus insularisandPomacanthus paru, with lesser contributions ofChaetodon sanctaehelenae, Thalassoma ascensionisand the cleaner shrimpLysmata grabhami. Two types of feeding mobs were consistently identified: less mobile mobs led by the surgeonfishAcanthurus bahianusandA. coeruleusand the more mobile mobs led by the African sergeantAbudefduf hoefleri. This is the first record ofA. hoeflerifrom outside of the Eastern Atlantic and also the first report of this species displaying mob-feeding behaviour. The principal follower of both mob types was the extremely abundantMelichthys niger, but the main aggressor differed:Stegastes lubbocki, a highly territorial herbivore, was the main aggressor ofAcanthurusmobs; andChromis multilineataa territorial fish while engaged in egg parental care, was the principal aggressor towardsAbudefdufmobs. Our study enhances the scarce information on reef fish feeding associations at the isolated Ascension Island and at oceanic islands in the Atlantic in general.
From Heathrow to Hong Kong
Authors: Backhouse John K.
Published: August 2016

A friend was travelling by air direct to Hong Kong. “When I leave Heathrow”, he asked, “on what bearing do you think the aeroplane will fly?” He gave me the latitudes of Heathrow and Hong Kong (approximately 51° and 22°N) and the longitude of the latter (114°E). My answer was not a good one. The reader is urged to make his or her own estimate before reading further.
Newton’s ‘experimental’ law of impacts
Authors: Cook Ian
Published: August 2016

For many years candidates (and teachers) involved in A-level work have quoted Newton’s experimental law of restitution as one of the principles enabling collision problems to be solved. It had always seemed to me that it is fortunate that such a simple law holds and also that it is a great pity that there is no simple relationship between the initial and final kinetic energies. Recently, however, I realised that, viewed in terms of invariance, the law is not at all surprising and also that there is a very simple way of dealing with the loss of kinetic energy.
Some features of the general Fermat point
Authors: Simons S.
Published: August 2016

Given a triangle with vertices P1, P2, P3 its Fermat point is defined as that point F which minimises the sum P1F + P2F + P3F. It is known that if each of the angles P1, P2, P3 is less than 120°, then F will be the point inside the triangle at which each pair of P1, P2, P3 subtend an angle of 120°, while if any of the angles at P1, P2, P3 exceed 120° then F will coincide with that vertex – see Figure (1).
A journey round the triangle Lester’s circle, Kiepert’s hyperbola and a configuration from Morley
Authors: Cundy H. Martyn
Published: August 2016

In a recent article [1], Ron Shail has given a Cartesian proof of an interesting theorem due to J. A. Lester. This states that, for any triangle, the circumcentre O, the nine-point centre O9 and the two Fermat points F and Fʹ, (which are the points of concurrence of the joins of its vertices to the vertices of equilateral triangles drawn outwards/inwards on the opposite sides), are concyclic. He refers to Lester's own treatment as needing complex coordinates with computer-assisted algebra; his own proof uses an unpromising method, and results in similar problems. Contemplation of the configuration would suggest that the location of the point of intersection of FFʹ with the Euler line OO9 might lead to a simple proof. The theorem is in fact a corollary from the properties of a remarkable configuration originating with Morley [2, p. 209], and shown in Figure 1. He did not deduce Lester’s result, nor label the crucial point J in the diagram, which was drawn without that particular intersection. Also involved in this figure is a rectangular hyperbola known by the name of its describer Kiepert [3]. It is helpful to discuss all three together. What follows is a journey through country nowadays rather unfamiliar, avoiding the computerised motorway and using older tracks via complex numbers, trilinear coordinates and Euclidean methods which reveal much more than is apparent from a Cartesian treatment.
A simple proof of Lester’s theorem
Authors: Rigby John
Published: August 2016

Lester’s theorem (1997) states that in any scalene triangle the two Fermat points F and F' (to be defined later), the nine-point centre N, and the circumcentre O, are concyclic, and that the pair of points O,F separates the pair N, F'. (In certain geometrical situations a line is regarded as a circle of infinite radius, so that the word ‘concyclic’ includes ‘collinear’ as a special case, but here ‘concyclic’ means ‘lying on a proper circle of finite radius’.) Previous proofs of Lester’s theorem have involved advanced techniques and/or computer algebra; to quote from Ron Shail’s recent article [1],

‘Lester’s original computer-assisted discovery and proof make use of her theory of “complex triangle coordinates” and “complex triangle functions”. ... A proof has also been given by Trott ... using the advanced concept of GrObner bases in the reduction of systems of polynomial equations to “diagonal” form. Trott’s work uses the computer algebra system Mathematica as an essential tool.’
Using spreadsheets to divide algebraic expressions and find roots of polynomials
Authors: Collyer A. A. , Pathan A.
Published: August 2016

In a recent paper on Horner’s Method [1], which includes a compact method for dividing expressions, we mentioned that some Computer Algebra Systems (CASs) such as DERIVE could be used to make the calculations, but that such programs, even when obtained through educational establishments, are overly expensive especially when most PCs have spreadsheets on them that could equally well do the calculations. Here we describe the use of an Excel spreadsheet to divide one expression by another, first by the method of detached coefficients and second by Horner’s Method of Synthetic Division (or simply synthetic division). A third example uses Horner’s Method to replace x by (x + c) to form a new expression [2], useful in the determination of the roots of a polynomial.
World order from chaotic beginnings
Authors: Newth Gerald
Published: August 2016

This article explains the variety of patterns seen in sequences defined by for bilinear functions of the form . The initial confusion of very different patterns can be understood by generalising from the real numbers to the whole complex plane, and simplified further by projecting each number from the plane onto the surface of a sphere. The sphere is finally projected onto a Mercator map on which the iterative sequences take on the simplest possible pattern, creating a link with the problem of rhumb-line navigation. The examples given below are typical, and should first be tried as a reminder of what can happen.
Transformed averages
Authors: Puritz Christian
Published: August 2016

My first introduction to the idea of an average, at the age of about eight, left me wondering why anyone would want to add up some numbers and then divide by how many there were. A helpful illustration (not forthcoming at the time!) might be as follows:

‘Suppose three boys are going on an outing and have each brought biscuits with them. They find that Alan has 7 biscuits, Jim has 6 and Tom has 11. They decide to pool their biscuits and share them out equally. So each gets (7 + 6 + 11)/3 = 24/3 = 8 biscuits. This is the average number of biscuits brought. So, they have the same total number of biscuits as they would have had if each had brought 8.’
An asymptotic formula for powers of binomial coefficients
Authors: Farmer Jeff D. , Leth Steven C.
Published: August 2016

The importance of teaching our students at all levels how to use computers as a problem-solving tool is well-recognised. Using numerical approximations to discover unknown formulas can be a powerful example. It is usually pointed out to the students that computer exploration alone is not sufficient and should be followed up whenever possible with a proof or at least some additional analysis. The importance of this is illustrated in the example below, in which there is compelling numerical evidence for an incorrect conclusion.
Cycles, bicycles, tricycles and more
Authors: Lewis Barry
Published: August 2016

I wanted to call this article, Counting permutations that contain a specified number of cycles of a given length but the Editor pointed out the problems this might cause the Production Editor - it simply wouldn't fit the running head. Hence the chosen title and the subject matter. There is a very well known result, nonetheless startling, about the relative frequency of derangements amongst the permutations of [r] = {1,2,3,… , r }.
Some comments on inverse arithmetic functions
Authors: Brown P. G.
Published: August 2016

In many of the basic courses in Number Theory, Finite Mathematics and Cryptography we come across the so-called arithmetic functions such as ϕn), σ(n), τ(n), μ(n), etc, whose domain is the set of natural numbers. These functions are well known and evaluated through the prime factor decomposition of n. It is less well known that these functions possess inverses (with respect to Dirichlet multiplication) which have interesting properties and applications.
Making the real projective plane
Authors: Irving Claire
Published: August 2016

The real projective plane is a classical mathematical object which plays an important role in several areas of mathematics, including topology. This article gives methods for making three-dimensional models of the real projective plane out of wool. By describing these models, and how to make them, the article aims to help the reader to visualise the real projective plane more easily.
Products of lengths of line segments associated with elliptical chords
Authors: Price Thomas E.
Published: August 2016

Suppose the unit circle is divided into n > 1 equal arcs and points are placed at the ends of the arcs. Choose one of these points to be the ‘base point’ and draw chords connecting each of the other points to the base point. (See Figure 1 for the case n = 8.) Then the product of the lengths of these chords equals n (see Sichardt). In a related article, Eisemann considered the product of the lengths of the (nondegenerate) perpendiculars drawn from the centre of the unit circle to these chords.
Magic Hexagons — Magic Moments
Authors: King David , Baker John
Published: August 2016

A ‘magic’ hexagon has rows of numbers in three directions that add to the same total. It is possible to construct such a hexagon from a honeycomb array of hexagons and from an array of triangles (Figure 1). There is known to be only one magic hexagon formed from hexagons. However, numerous magic arrangements are possible for the hexagon of triangles and these arrangements have many additional interesting properties. In this article we give the reasons why such configurations are possible, we look at the number of arrangements possible when there are 2 triangles on each side of the hexagon and we show that in general the arrangements are balanced in many ways – including that they are physically balanced, a property we call ‘magic moments’.
A solution to a cubic – Barker's equation for parabolic trajectories
Authors: Pathan Alex , Collyer Tony
Published: August 2016

Except for the circle, for which the true anomaly v is proportional to the time t, the position of a body in orbit about a central body at a given time is simplest to derive for a parabola. The classical determination of the time of flight on a parabolic trajectory is through the integration of the dynamic equations of motion. (See Appendix.)
Defining sets for magic squares
Authors: Keedwell A. D.
Published: August 2016

A topic of current interest is that of finding defining sets (preferably smallest defining sets) for various combinatorial structures such as latin squares and block designs, so it seemed interesting (though of no practical use) to try to solve the same problem for magic squares of small size. (The germ of this idea was suggested in the Gazette Note [1] of 1988 under the sub-heading ‘Squares from clues’.)
A theorem of M. L. Urquhart's and some consequences
Authors: Leslie R. T.
Published: August 2016

In an obituary of M. L. Urquhart in [1], David Elliott quotes him as claiming that Urquhart's theorem (below) is the most elementary theorem of Euclidean Geometry ‘since it involves only the concepts of straight line and distance’.

Urquhart's theorem

Let AC and AE be two straight lines.

Let B be a point on AC, D a point on AE, and suppose that BE and CD intersect at F.

If AB + BF = AD + DF then AC + CF = AE + EF. (1)
Euler and triangle geometry
Authors: Leversha Gerry , Smith G. C.
Published: August 2016

There is a very easy way to produce the Euler line, using transformational arguments. Given a triangleABC, letAʹBʹ'Cbe the medial triangle, whose vertices are the midpoints of the sides. These two triangles are homothetic: they are similar and corresponding sides are parallel, and the centroid,G, is their centre of similitude. Alternatively, we say thatAʹBʹCcan be mapped toABCby means of an enlargement, centreG, with scale factor –2.
Further forays into n dimensions
Authors: Quadling Douglas
Published: August 2016

In an article in the Gazette for November 2005 [1] Martin Griffiths described some ideas which he had explored with a Further Mathematics class based on extensions of the Platonic solids in more than 3 dimensions. This reminded me of an investigation I had myself undertaken with similar groups of students. Whilst giving a glimpse of ways in which mathematics can develop through generalisation, it also led to some unusual applications of the binomial theorem.
Euler’s and Barker’s equations: A geometric derivation of the time of flight along parabolic trajectories
Authors: Pathan Alex
Published: August 2016

The parabolic orbit is rarely found in nature although the orbits of some comets have been observed to be very close to parabolic. The parabola is of interest mathematically because it represents the boundary between the open and closed orbit forms. An object moving along a parabolic path is on a oneway trip to infinity never being able to retrace the same orbit again. The velocity of such an object is the escape velocity and its total energy is zero.
Pseudoperfect numbers with no small prime divisors
Authors: Shiu Peter
Published: August 2016

A perfect number is a number which is the sum of all its divisors except itself, the smallest such number being 6. By results due to Euclid and Euler, all the even perfect numbers are of the form 2P-1(2p - 1) where p and 2p - 1 are primes; the latter one is called a Mersenne prime. Whether there are infinitely many Mersenne primes is a notoriously difficult problem, as is the problem of whether there is an odd perfect number.
A generalisation of Ioachimescu’s constant
Authors: Sȋntămărian Alina
Published: August 2016

In the problem proposed by A. G. Ioachimescu in 1895, it is asked to be shown that the sequence , defined by , for each , is convergent and its limit lies between -2 and -1.

There have been given many generalisations and other results regarding Ioachimescu’s problem in the literature (see, for example, [2], [3], [4, Theorem 1, parts (a) and (b)], [5, problem P2, parts (i) and (ii)],).
Testing the cultural group selection hypothesis in Northern Ghana and Oaxaca
Authors: Acedo-Carmona Cristina , Gomila Antoni
Published: August 2016

We examine the cultural group selection (CGS) hypothesis in light of our fieldwork in Northern Ghana and Oaxaca, highly multi-ethnic regions. Our evidence fails to corroborate two central predictions of the hypothesis: that the cultural group is the unit of evolution, and that cultural homogenization is to be expected as the outcome of a selective process.
The sketch is blank: No evidence for an explanatory role for cultural group selection
Authors: Krasnow Max M. , Delton Andrew W.
Published: August 2016

As evidence that cultural group selection has occurred, Richerson et al. simply retrodict that humans use language, punish each other, and have religion. This is a meager empirical haul after 30 years. This contrasts sharply with the adaptationist approach to human behavior – evolutionary psychology – which has produced scores of novel, specific, and empirically confirmed predictions.
The disunity of cultural group selection
Authors: Morin Olivier
Published: August 2016

I argue that demographic selection, migration, and cultural diffusion, three mechanisms of institutional change, have little in common. Two of these lack the key features associated with group selection: they do not present us with group-level selection pressures counteracting individual-level ones, need not produce behavioral altruism, and do not require competition between groups whose members cooperate preferentially with one another. Cultural norms vary, change, and influence cooperation; but that is not group selection.
Is cultural group selection enough?
Authors: Read Dwight
Published: August 2016

Richerson et al. propose cultural group selection (CGS) as the basis for understanding the evolution of cultural systems. Their proposal does not take into account the nature of cultural idea systems as being constituted at an organizational, rather than an individual level. The sealing partners of the Netsilik Inuit exemplify the problem with their account.
Cultural group selection in the light of the selection of extended behavioral patterns
Authors: Simon Carsta
Published: August 2016

The cultural group selection hypothesis is supported by considerations of short-term and long-term behavioral patterns of group members, and the short-term and long-term consequences of that behavior. The key to understanding cooperation lies in understanding that the effect of an extended behavioral pattern does not equal – and might even be opposite to – the added effects of its parts.
Multi-level selection, social signaling, and the evolution of human suffering gestures: The example of pain behaviors
Authors: Vigil Jacob M. , Kruger Eric
Published: August 2016

Pain suffering has been naturally selected to be experienced and expressed within a wider social system. The communication of pain improves group coordination and decision-making about engaging in resource dependent and potentially risky endeavors. Recent findings warrant the development of a cohesive framework for understanding the reciprocal nature of pain expression and individual and group-level outcomes that can generate novel predictions on the heuristical expression of human suffering in naturalistic and clinical settings.
Rome was not built in one day: Underlying biological and cognitive factors responsible for the emergence of agriculture and ultrasociality
Authors: Grotuss Jason , Beard Sarah Jean
Published: August 2016

Agriculture represented a major transition in human evolution, but the appearance of ultrasociality must have included previous steps. We argue that ultrasociality would not have suddenly emerged with agriculture, but rather developed from pre-existing cognitive and social mechanisms. Discussions must include necessary depth about the historical origins of human ultrasociality, and agriculture's aftereffects on large-scale social organization.
Ultrasociality, class, threat, and intentionality in human society
Authors: McCain Roger A.
Published: August 2016

Gowdy & Krall neglect an important aspect of human societies, which is that class systems are not genetically based but rather based on threat. In turn, threat presupposes intentionality, so seems to distinguish human from arthropod ultrasociality. Class systems, in turn, seem to explain the distinctive mixture of persistence and instability characteristic of human, but not arthropod, ultrasocial populations.
The day of reckoning: Does human ultrasociality continue?
Authors: Ristau Carolyn A.
Published: August 2016

To counter human ultrasociality, alternative communities can arise (ongoing), and, unlike insects, lower echelons can unite and rebel. Examples include movements such as: “Black Lives Matter,” “Fight for $15,” “Occupy,” and the “Village Movement.” To strengthen ultrasociality, a surplus bottom echelon can be reduced: for example, by means such as imprisoning Blacks, deporting immigrants, wars, and the Holocaust. Alternatively, a new structure could be created, for example, ISIL (even more ultrasocial?).
Malthus redux, and still blind in the same eye
Authors: Ross Don
Published: August 2016

Gowdy & Krall (G&K) essentially recapitulate Malthus's classic argument for ecological pessimism in modern biological dress. Their reasoning also reproduces Malthus's blindness to the implications of technological innovation. Agriculture might have suppressed human individualism as G&K insist, but technology has tended to foster it. This complicates human ecological prospects in a non-Malthusian way, and it might additionally provide the resources for deliverance from disaster.
Human agricultural economy is, and likely always was, largely based on kinship – Why?
Authors: Rusch Hannes , Voland Eckart
Published: August 2016

We question the sequence of evolutionary transitions leading to ultrasociality in humans proposed by Gowdy & Krall. Evidence indicates that families are, and likely always have been, the primary productive units in human agricultural economies, suggesting that genetic relatedness is key to understanding when the suppression of individual autonomy to the benefit of subsistence groups, that is, extended families, evolved.
Does ultrasociality really exist – and is it the best predictor of human economic behaviors?
Authors: Stith Sarah S. , Vigil Jacob M.
Published: August 2016

We agree that human economic structures can be informed by comparative analyses; however, we do not agree with several of Gowdy & Krall's specific assertions, which may hinder the generative potential of their model. We discuss these limitations from both biological and economic perspectives, and offer an alternative explanation for the expression of human economic behaviors based on individual optimization strategies.
Differences in autonomy of humans and ultrasocial insects
Authors: Vranka Marek , Bahník Štěpán
Published: August 2016

The target article is built on an analogy between humans and ultrasocial insects. We argue that there are many important limitations to the analogy that make any possible inferences from the analogy questionable. We demonstrate the issue using an example of the difference between a loss of autonomy in humans and in social insects.
Humans are ultrasocial and emotional
Authors: Williams Lisa A. , Bliss-Moreau Eliza
Published: August 2016

Given the highly social nature of the human emotion system, it is likely that it subserved the evolution of ultrasociality. We review how the experience and functions of human emotions enable social processes that promote ultrasociality (e.g., cooperation). We also point out that emotion may represent one route to redress one of the negative consequences of ultrasociality: ecosystem domination.
Laying the foundation for evonomics
Authors: Wilson David Sloan
Published: August 2016

The target article is a major step toward integrating the biological and human-related sciences. It is highly relevant to economics and public policy formulation in the real world, in addition to its basic scientific import. My commentary covers a number of points, including avoiding an excessively narrow focus on agriculture, the importance of multilevel selection and complex systems theory, and utopic versus dystopic scenarios for the future.
Computational specificity in the human brain
Authors: Shine James M. , Eisenberg Ian , Poldrack Russell A.
Published: August 2016

Although meta-analytic neuroimaging studies demonstrate a relative lack of specificity in the brain, this evidence may be the result of limits inherent to these types of studies. From this perspective, we review recent findings that suggest that brain function is most appropriately categorized according to the computational capacity of each brain system, rather than the specific task states that elicit its activity.
The Way Out: Closure of and Departure from Anglican Religious Communities
Authors: Quint Francesca
Published: August 2016

Anglican religious communities are currently experiencing decline. Member numbers are decreasing as their average age increases, recruitment of young people is virtually impossible and it is not uncommon to find a small and dwindling group of elderly religious inhabiting premises designed for a time when committing oneself to life as a member of a religious order was much more fashionable. There are several underlying reasons: young people are offered a wider and more diverse array of possible occupations; employment with a specific employer is no longer undertaken for life, but people tend to move from one job to another and from one sector to another; women in particular have more choices than previously and for those with a religious vocation the priesthood is a more exciting alternative; and, bearing in mind that many Anglican religious communities incline to the Anglo-Catholic end of the spectrum, the Ordinariate beckons.
Parliamentary Report
Authors: Cranmer Frank
Published: August 2016

On 9 May, the EU Justice Sub-Committee of the House of Lords, chaired by Baroness Helena Kennedy QC, published a report on the Government's proposals to repeal the Human Rights Act and replace it with a new Bill of Rights – and suggested that there was a forceful case for a Government rethink:

The proposals the Secretary of State outlined did not appear to depart significantly from the Human Rights Act – we note in particular that all the rights contained within the ECHR are likely to be affirmed in any British Bill of Rights. His evidence left us unsure why a British Bill of Rights was really necessary. If a Bill of Rights is not intended to change significantly the protection of human rights in the UK, we recommend the Government give careful thought before proceeding with this policy … the repeal of the Human Rights Act and its replacement by a Bill of Rights would be a constitutional change of the greatest significance.
Larger or Broader: Performance Implications of Size and Diversity of the Knowledge Worker's Egocentric Network
Authors: Chen Liang , Gable Guy G.
Published: August 2016

Management scholars and practitioners emphasize the importance of the size and diversity of a knowledge worker's social network. Constraints on knowledge workers' time and energy suggest that more is not always better. Further, why and how larger networks contribute to valuable outcomes deserves further understanding. In this study, we offer hypotheses to shed insight on the question of the diminishing returns of large networks and the specific form of network diversity that may contribute to innovative performance among knowledge workers. We tested our hypotheses using data collected from 93 R&D engineers in a Sino-German automobile electronics company located in China. Study findings identified an inflection point, confirming our hypothesis that the size of the knowledge worker's egocentric network has an inverted U-shaped effect on job performance. We further demonstrate that network dispersion richness (the number of cohorts that the focal employee has connections to) rather than network dispersion evenness (equal distribution of ties across the cohorts) has more influence on the knowledge worker's job performance. Additionally, we found that the curvilinear effect of network size is fully mediated by network dispersion richness. Implications for future research on social networks in China and Western contexts are discussed.