PZT-like structural phase transitions in the BiFeO3-KNbO3 solid solution

Despite the high prominence of the perovskites BiFeO3 and KNbO3 the solid solution between the two has received little attention. We report a detailed neutron and synchrotron x-ray powder diffraction, and Raman spectroscopy study which demonstrate an R3c → P4mm → Amm2 series of structural phase transitions similar to that exhibited by the PbZrO3 – PbTiO3 solid solution

Redshift clustering in the Hubble Deep Field

We present initial results from a redshift survey carried out with the Low Resolution Imaging Spectrograph on the 10~m W. M. Keck Telescope in the Hubble Deep Field. In the redshift distribution of the 140 extragalactic objects in this sample we find 6 strong peaks, with velocity dispersions of ${\sim}400${\kms}. The areal density of objects within a particular peak, while it may be non-uniform, does not show evidence for strong central concentration. These peaks have characteristics (velocity dispersions, density enhancements, spacing, and spatial extent) similar to those seen in a comparable redshift survey in a different high galactic latitude field (Cohen et al 1996), confirming that the structures are generic. They are probably the high redshift counterparts of huge galaxy structures (``walls'') observed locally.Comment: 14 pages, including 2 figures, to appear in ApJ Letter

Peer mentorship and positive effects on student mentor and mentee retention and academic success

This study examined how the introduction of peer mentorship in an undergraduate health and social welfare programme at a large northern university affected student learning. Using an ethnographic case study approach, the study draws upon data collected from a small group of mentors and their mentees over a period of one academic year using interviews, reflective journals, assessment and course evaluation data. Analysis of the data collected identified a number of key findings: peer mentorship improves assessment performance for both mentee and mentor; reduces stress and anxiety, enhances participation and engagement in the academic community, and adds value to student outcomes

Neocortical hyperexcitability in a genetic model of absence seizures and its reduction by levetiracetam

PURPOSE: To study the effect of the antiepileptic drug levetiracetam (LEV) on the patterns of intrinsic optical signals (IOSs) generated by slices of the somatosensory cortex obtained from 3- and 6-month-old WAG/Rij and age-matched, nonepileptic control (NEC) rats. METHODS: WAG/Rij and NEC animals were anesthetized with enfluorane and decapitated. Brains were quickly removed, and neocortical slices were cut coronally with a vibratome, transferred to a submerged tissue chamber, and superfused with oxygenated artificial cerebrospinal fluid (aCSF). Slices were illuminated with a dark-field condensor and examined with a x2.5 objective; images were processed with a real time digital video image-enhancement system. Images were acquired before (background) and during electrical stimulation with a temporal resolution of 10 images/s and were displayed in pseudocolors. Extracellular stimuli (200 micros; <4 V) were delivered through bipolar stainless steel electrodes placed in the white matter. RESULTS: IOSs recorded in NEC slices bathed in control aCSF became less intense and of reduced size with age (p < 0.05); this trend was not seen in WAG/Rij slices. Age-dependent decreases in IOS intensity and area size were also seen in NEC slices superfused with aCSF containing the convulsant 4-aminopyridine (4-AP, 5 microM); in contrast, significant increases in both parameters occurred with age in 4-AP-treated WAG/Rij slices (p < 0.05). Under any of these conditions, the IOS intensity and area size slices were larger in WAG/Rij than in NEC slices. LEV (50-500 microM) application to WAG/Rij slices caused dose-dependent IOS reductions that were evident both in control and in 4-AP-containing aCSF and were more pronounced in 6-month-old tissue. CONCLUSIONS: These data demonstrate age-dependent IOS modifications in NEC and WAG/Rij rat slices and identify a clear pattern of hyperexcitability that occurs in 6-month-old WAG/Rij neocortical tissue, an age when absence seizures occur in all animals. The ability of LEV to reduce these patterns of network hyperexcitability supports the potential use of this new antiepileptic drug in primary generalized epileptic disorders

Ten strategies for avoiding and overcoming authorship conflicts in academic publishing

For better or for worse, authorship is a currency in scholarly research and advancement. In scholarly writing, authorship is widely acknowledged as a means of conferring credit but is also tied to concepts such as responsibility and accountability. Authorship is one of the most divisive topics both at the level of the research team and more broadly in the academy and beyond. At present, authorship is often the primary way to assert and receive credit in many scholarly pursuits and domains. Debates rage, publicly but mostly privately, regarding authorship. Here we attempt to clarify key concepts related to authorship informed by our collective experiences and anchored in relevant contemporary literature. Rather than dwelling on the problems, we focus on proactive strategies for creating more just, equitable, and transparent avenues for minimizing conflict around authorship and where there is adequate recognition of the entire process of knowledge generation, synthesis, sharing, and application with partners within and beyond the academy. We frame our ideas around 10 strategies that collectively constitute a roadmap for avoiding and overcoming challenges associated with authorship decisions

Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of M^(k,e)_R ≤ -19.8 + 5 log h mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (Ω_M = 0.2, Ω_Λ = 0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h^(-1) kpc and rest-frame velocity differences of less than 1000 km s^(-1). The fractional luminosity in pairs is modeled as f_L(Δv, r_p, M^(k,e)_τ)(1 + z)^(m,L), where [f_L, m_L] are [0.14 ± 0.07, 0 ± 1.4] and [0.37 ± 0.7, 0.1 ± 0.5] for r_p ≤ 50 and 100 h^(-1) kpc, respectively (Ω_M = 0.2, Ω_Λ = 0.8). The value of mL is about 0.6 larger if Λ = 0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M_1, M_2 ≥ 0.2M*) is 0.02 ± 0.01(1 + z)^(0.1±0.5)M* Gyr^(-1). Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, δM/M 0.15M*/M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*

Aristotelian Essentialism: Essence in the Age of Evolution

The advent of contemporary evolutionary theory ushered in the eventual decline of Aristotelian Essentialism (Æ) – for it is widely assumed that essence does not, and cannot have any proper place in the age of evolution. This paper argues that this assumption is a mistake: if Æ can be suitably evolved, it need not face extinction. In it, I claim that if that theory’s fundamental ontology consists of dispositional properties, and if its characteristic metaphysical machinery is interpreted within the framework of contemporary evolutionary developmental biology, an evolved essentialism is available. The reformulated theory of Æ offered in this paper not only fails to fall prey to the typical collection of criticisms, but is also independently both theoretically and empirically plausible. The paper contends that, properly understood, essence belongs in the age of evolution

The General Practice Care of People With Intellectual Disability: Barriers and Solutions

A questionnaire exploring general practitioners' (GPs) perceptions of the barriers and solutions to providing health care to people with intellectual disability was sent to 912 randomly selected GPs throughout Australia. a response rate of 58% was obtained. Results indicated that numerous barriers compromised the quality of health care able to be provided to people with intellectual disability. communications difficulties with patients and other health professionals, and problems in obtaining patient histories stood out as the two most significant barriers. A range of other barriers were identified, including GPs' lack of training and experience, patients' poor compliance with management plans, consultation time constraints, difficulties in problem determination, examination difficulties, poor continuity of care, and GPs' inadequate knowledge of the services and resources available. General practitioners also suggested numerous solutions to these barriers, and emphasized the need for increased opportunities for education and training in intellectual disability. The GPs showed an overwhelming interest to be involved in further education. Other major solutions included increasing consultation duration or frequency, proactively involving families and carers in patients' ongoing health care, and increasing remuneration