ABSTRACT
To enhance equity and diversity in undergraduate biology, recent research in biology education focuses on best practices that reduce learning barriers for all students and improve academic performance. However, the majority of current research into student experiences in introductory biology takes place at large, predominantly White institutions. To foster contextual knowledge in biology education research, we harnessed data from a large research coordination network to examine the extent of academic performance gaps based on demographic status across institutional contexts and how two psychological factors, test anxiety and ethnicity stigma consciousness, may mediate performance in introductory biology. We used data from seven institutions across three institution types: 2-year community colleges, 4-year inclusive institutions (based on admissions selectivity; hereafter, inclusive), and 4-year selective institutions (hereafter, selective). In our sample, we did not observe binary gender gaps across institutional contexts, but found that performance gaps based on underrepresented minority status were evident at inclusive and selective 4-year institutions, but not at community colleges. Differences in social psychological factors and their impacts on academic performance varied substantially across institutional contexts. Our findings demonstrate that institutional context can play an important role in the mechanisms underlying performance gaps.
Subject(s)
Academic Performance , Students , Humans , Learning , Minority Groups , UniversitiesABSTRACT
BACKGROUND: Cytokine release storm (CRS) is a potentially fatal, hyperinflammatory condition common to both coronavirus disease 2019 (COVID-19) and reactive hemophagocytic lymphohistiocytosis (rHLH). We present our experience with the use of a diagnostic score, developed for rHLH, in a kidney transplant recipient hospitalized with COVID-19. METHODS: We applied the H-Score to risk-stratify our patient to help predict his hospital course. This study was exempt from requiring specific Institutional Review Board approval, but met all the criteria required by our institution for this type of study and report including consent from the patient. RESULTS: The calculated H-Score for our patient fell below the diagnostic cut-off value for rHLH. Because rHLH is characterized by CRS, we expected him to have a milder hospital course with COVID-19. Correlating with his below cut-off H-score, the patient had a more benign than expected hospital course. CONCLUSIONS: Because this is only a single case, we plan to retrospectively review a series of patients to validate our initial experience-that a low H-Score may correlate with a milder hospital course in kidney transplant patients with COVID-19.
Subject(s)
Coronavirus Infections/immunology , Coronavirus Infections/therapy , Immunocompromised Host , Pneumonia, Viral/immunology , Pneumonia, Viral/therapy , Severity of Illness Index , Betacoronavirus , COVID-19 , Cytokine Release Syndrome/diagnosis , Cytokine Release Syndrome/etiology , Humans , Kidney Transplantation , Male , Middle Aged , Pandemics , Prognosis , Retrospective Studies , SARS-CoV-2ABSTRACT
Different families of thermoelectric materials have been investigated since the discovery of thermoelectric effects in the mid-19th century, materials mostly belonging to the family of degenerate semi-conductors. In the last 20 years, new thermoelectric materials have been investigated following different theoretical proposals, showing that nanostructuration, electronic correlations and complex crystallographic structures (low dimensional structures, large number of atoms per lattice, presence of 'rattlers' ) could enhance the thermoelectric properties by enhancing the Seebeck coefficient and/or reducing the thermal conductivity. In this review, the different strategies used to optimize the thermoelectric properties of oxides and chalcogenides will be presented, starting with a review on thermoelectric oxides. The thermoelectric properties of sulfides and selenides will then be discussed, focusing on layered materials and low dimensional structures (TiS2 and pseudo-hollandites). Some sulfides with promising ZT values will also be presented (tetrahedrites and chalcopyrites).
ABSTRACT
[Purpose] This study aimed to evaluate the anti-inflammatory and analgesic effects of intraoral application of low-level laser therapy (660â nm) to control pain, swelling and interincisal opening following the extraction of mandibular third molars. [Subjects and Methods] Ten patients underwent removal of lower third molars using the same surgical protocol and pharmacological approach. In the postoperative period, all patients received four consecutive daily sessions of low-level laser therapy, beginning 24 hours after the surgery. Intraoral applications using the diode laser with 660â nm wavelength in the continuous scan mode were performed covering the entire surgical area, which was divided into four quadrants, each of 1â cm(2) area at a distance of 1â cm. The energy applied at each point was 5â J/cm(2) during 8 seconds. [Results] The swelling and interincisal opening returned to normal 24 hours after the first low-level laser therapy application (Friedman test). Moreover, the pain intensity was reduced on the third postoperative day, according to the Friedman test. [Conclusion] Low-level laser therapy (660â nm), at the dosimetry used in this study, was effective in reducing postoperative pain and swelling following oral surgery.
ABSTRACT
Emotional stress is a constant companion of tinnitus patients, since this phantom sound can unfortunately be a very effective stressor. However, the mechanism of stress contribution to the onset or progression of tinnitus remains unknown. Here, we review the pathways induced by emotional stress and the outcome of their induction: corticosteroid-dependent changes in gene expression, epigenetic modulations, and impact of stress on neuronal plasticity and neurotransmission. Using clinical examples, we demonstrate the presence of emotional stress among tinnitus patients and we present methods to measure the degree of stress. The evidence causally linking emotional stress with tinnitus is still indirect-the main difficulty lies in the inaccessibility of human auditory tissues and the inability to directly measure tinnitus-induced psychological distress in animal models. However, we believe that translational research is the future way of filling this gap, finding the answers, and thereby improving both the diagnosis and treatment of tinnitus patients.
Subject(s)
Auditory Perception , Brain/physiopathology , Hypothalamo-Hypophyseal System/physiopathology , Pituitary-Adrenal System/physiopathology , Stress, Psychological/physiopathology , Tinnitus/physiopathology , Humans , Models, Neurological , Stress, Psychological/psychology , Tinnitus/diagnosis , Tinnitus/psychologyABSTRACT
A round robin test aiming at measuring the high-temperature thermoelectric properties was carried out by a group of European (mainly French) laboratories (labs). Polycrystalline skutterudite Co0.97Ni0.03Sb3 was characterized by Seebeck coefficient (8 labs), electrical resistivity (9 labs), thermal diffusivity (6 labs), mass volume density (6 labs), and specific heat (6 labs) measurements. These data were statistically processed to determine the uncertainty on all these measured quantities as a function of temperature and combined to obtain an overall uncertainty on the thermal conductivity (product of thermal diffusivity by density and by specific heat) and on the thermoelectric figure of merit ZT. An increase with temperature of all these uncertainties is observed, in agreement with growing difficulties to measure these quantities when temperature increases. The uncertainties on the electrical resistivity and thermal diffusivity are most likely dominated by the uncertainty on the sample dimensions. The temperature-averaged (300-700 K) relative standard uncertainties at the confidence level of 68% amount to 6%, 8%, 11%, and 19% for the Seebeck coefficient, electrical resistivity, thermal conductivity, and figure of merit ZT, respectively. Thermal conductivity measurements appear as the least accurate. The moderate value of the temperature-averaged relative expanded (confidence level of 95%) uncertainty of 17% on the mean of ZT is essential in establishing Co0.97Ni0.03Sb3 as a high temperature standard n-type thermoelectric material.
ABSTRACT
An efficient synthesis route is proposed to obtain single phase powder ceramic of CaFe5O7. This complex structure can be described as an intergrowth between one CaFe2O4 unit and n = 3 slices of FeO Wüstite-type structure. A detailed structural study has been carried out at room temperature combining transmission electron microscopy (TEM) observations (ED, HREM), scanning transmission electron microscopy (STEM-HAADF), and X-ray diffraction data. The analysis of these data has revealed an unexpected supercell with a monoclinic symmetry. From the hkl conditions deduced from the electron diffraction study and the analysis of X-ray diffraction data by simulated annealing, a structural model considering the centrosymmetric P21/m setting can be proposed. In addition the first magnetic and electrical transport measurements are reported showing a sharp peak in magnetic susceptibility and a strong localization around 360 K, associated to a structural change from monoclinic setting to orthorhombic one.
ABSTRACT
Loudness is the primary perceptual correlate of sound intensity. The relationship between sound intensity and loudness is not fixed, and can be modified by short-term sound deprivation or stimulation. Deprivation increases sound sensitivity, whereas stimulation decreases it. We review the effects of short-term auditory deprivation and stimulation on the auditory central nervous system of humans and animals, and we extend the discussion to permanent auditory deprivation (hearing loss) and auditory pathologies of loudness perception. Although there is sufficient evidence to conclude that loudness can be modulated in normal hearing listeners by temporary sound deprivation and stimulation, evidence is scanter for the hearing-impaired listeners. In addition, cortical effects of sound deprivation and stimulation in humans, which may correlate with loudness coding, are still largely unknown and should be the target of future research.
Subject(s)
Acoustic Stimulation/adverse effects , Hearing Loss/etiology , Hyperacusis/etiology , Tinnitus/etiology , Animals , HumansABSTRACT
AIMS/HYPOTHESIS: We analysed the genomic organisation of miR-153, a microRNA embedded in genes that encode two of the major type 1 diabetes autoantigens, islet-associated protein (IA)-2 and IA-2ß. We also identified miR-153 target genes that correlated with IA-2ß localisation and function. METHODS: A bioinformatics approach was used to identify miR-153's genomic organisation. To analyse the co-regulation of miR-153 and IA-2ß, quantitative PCR analysis of miR-153 and Ia-2ß (also known as Ptprn2) was performed after a glucose stimulation assay in MIN6B cells and isolated murine pancreatic islets, and also in wild-type Ia-2 (also known as Ptprn), Ia-2ß single knockout and Ia-2/Ia-2ß double knockout mouse brain and pancreatic islets. Bioinformatics identification of miR-153 target genes and validation via luciferase reporter assays, western blotting and quantitative PCR were also carried out. RESULTS: Two copies of miR-153, miR-153-1 and miR-153-2, are localised in intron 19 of Ia-2 and Ia-2ß, respectively. In rodents, only miR-153-2 is conserved. We demonstrated that expression of miR-153-2 and Ia-2ß in rodents is partially co-regulated as demonstrated by a strong reduction of miR-153 expression levels in Ia-2ß knockout and Ia-2/Ia-2ß double knockout mice. miR-153 levels were unaffected in Ia-2 knockout mice. In addition, glucose stimulation, which increases Ia-2 and Ia-2ß expression, also significantly increased expression of miR-153. Several predicted targets of miR-153 were reduced after glucose stimulation in vitro, correlating with the increase in miR-153 levels. CONCLUSIONS/INTERPRETATION: This study suggests the involvement of miR-153, IA-2ß and miR-153 target genes in a regulatory network, which is potentially relevant to insulin and neurotransmitter release.
Subject(s)
Brain/metabolism , MicroRNAs/genetics , Pancreas/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 8/metabolism , Animals , Blotting, Western , Cell Line, Tumor , Female , Male , Mice , Mice, Knockout , Receptor-Like Protein Tyrosine Phosphatases, Class 8/genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The oxycarbonate Sr7Co4(CO3)O11.36 exhibits a peculiar structure that has been characterized by combining transmission electron microscopy analyses and neutron diffraction. It consists of a regular intergrowth between the m = 2 and carbonated m = 3 members of the Sr(m+1)Co(m)O3(m+1) Ruddlesden-Popper (RP) series, Sr3Co2O5.87 and Sr4Co2(CO3)O5.49, respectively. A description of the structure is proposed to provide identification of the different building blocks. This material is semiconducting and presents a complex magnetic behavior, characteristic of what is observed for the RP(2) or RP(3) series, with a cobalt valency close to 2.7.
ABSTRACT
An original Ruddlesden-Popper phase, La(0.77)Sr(3.23)Co(2.75)C(0.25)O(8.40+δ), was isolated and studied by electron, X-ray, and neutron diffraction. This structure has complex crystal chemistry resulting from a high degree of flexibility in the structure, comprising the disordered introduction of carbonates into a cobalt layer and an important oxygen deficiency with a preferential repartition of vacancies along the layers stacking sequence. The former is necessary for the stabilization of the system, while the latter can be tuned by postsynthetic treatment, yielding in a large variety of cobalt species formal oxidation states ranging from Co(2+)/Co(3+) in the as-made phase to Co(3+)/Co(4+) when annealed under oxygen pressure. The potential richness deriving from this flexibility is illustrated in terms of the magnetotransport properties and includes a resistivity that varies within a range of 5 orders of magnitude after modulation of the oxygen content with the appearance of negative magnetoresistance and ferromagnetic interactions due to Co(3+)/Co(4+) mixed-valence state.
Subject(s)
Carbon/chemistry , Cobalt/chemistry , Lanthanum/chemistry , Oxides/chemistry , Oxygen/chemistry , Strontium/chemistry , Neutron DiffractionABSTRACT
First record of necrophagy by Scybalocanthon nigriceps Harold (Coleoptera, Scarabaeidae, Scarabaeinae). The S. nigriceps specimen was observed making small cuts and removing portions of the carcass of a frog Haddadus binotatus (Spix) in February 24, 2011, in Serra do Japi, São Paulo State, Brazil. This note presents another record of necrophagy for Scybalocanthon.
Primeiro relato de necrofagia por Scybalocanthon nigriceps Harold (Coleoptera, Scarabaeidae, Scarabaeinae). O espécime de S. nigriceps foi observado fazendo pequenos cortes e removendo porções da carcaça da rã Haddadus binotatus (Spix) em 24 de fevereiro de 2011 na Serra do Japi, Estado de São Paulo, Brasil. Esta nota apresenta mais um registro de negrofagia para Scybalocanthon.
ABSTRACT
The aim of this work is to evaluate and discuss river water quality trends over the last decade in ten watersheds where diffuse pollution represents more than half of the annual load of phosphorus (P) and nitrogen (N). Trend analyses taking into account flow data indicate a significant reduction of total P in eight rivers, of ammonia N in five rivers, of nitrate + nitrite in four rivers, of total filtered N in three rivers and of suspended solids in two rivers. An increase of turbidity was observed in four rivers and, for fecal coliforms, no trends. P decrease can be explained by reduced mineral P inputs on cropped lands related to means such as agro-environmental fertilization plans and addition of phytase in pig and poultry feed. However, for seven of them, median P concentrations remain at least two times greater than the Québec water quality guideline for protection of rivers against eutrophication. Concentrations of other parameters remain problematic in some rivers too. These results indicate the need to continue the efforts for further diffuse pollution reduction. Future work should better quantify actions taken at the watershed scale to reduce diffuse pollution.
Subject(s)
Water Microbiology/standards , Water Pollution , Water Supply/standards , Water/chemistry , Agriculture , Enterobacteriaceae/isolation & purification , Feces/microbiology , Nitrogen/chemistry , Phosphorus/chemistry , Quebec , Time FactorsABSTRACT
Previous angle-resolved photoemission spectroscopy experiments in NaxCoO2 reported both a strongly renormalized bandwidth near the Fermi level and moderately renormalized Fermi velocities, leaving it unclear whether the correlations are weak or strong and how they could be quantified. We explain why this situation occurs and solve the problem by extracting clearly the coherent and incoherent parts of the band crossing the Fermi level. We show that one can use their relative weight to estimate self-consistently a quasiparticle weight Z=0.15+/-0.05. We suggest this method could be a reliable way to study the evolution of correlations in cobaltates and for comparison with other strongly correlated systems.
ABSTRACT
We have synthesized single crystals of the misfit-layered cobalt oxide, [Bi(1.5)Pb(0.5)Sr(2)O(4-δ)][CoO(2)](1.86), with quadruple NaCl-type layers, using a flux method, and measured their transport properties. From structural refinements, it is found that the modulation in the BiO layer observed in [Bi(1.74)Sr(2)O(4-δ)](RS)[CoO(2)](1.82) is suppressed by Pb substitution. The in-plane resistivity, thermopower, and Hall coefficient are 4.3 mΩ cm, 101 µV K(-1), and 1 × 10(-2) cm(3) C(-1) at 300 K, respectively; these are consistent with those of the misfit-layered cobalt oxides. All of these values are smaller than those of [Bi(1.74)Sr(2)O(4)][CoO(2)](1.82), indicating that the carrier concentration is larger than that of the undoped crystal. Moreover, the low T upturn of resistivity observed for most of the cobalt misfit oxides is replaced by a metallic behavior, following a T(2) dependence, indicating strong correlations in the Pb-doped crystal. Also, the magnetoresistance, usually negative for misfit oxides, is replaced by a small positive magnetoresistance. Doping with Pb is thus an efficient way to suppress the low T localized behavior usually observed for misfits.
ABSTRACT
The search for multifunctional materials as multiferroics to be applied in microelectronic or for new, chemically stable and nontoxic, thermoelectric materials to recover waste heat is showing a common interest in the oxides whose structures contain a triangular network of transition-metal cations. To illustrate this point, two ternary systems, Ba-Co-O and Ca-Co-O, have been chosen. It is shown that new phases with a complex triangular structure can be discovered, for instance, by introduction of Ga (3+) into the Ba-Co-O system to stabilize Ba 6Ga 2Co 11O 26 and Ba 2GaCo 8O 14, which both belong to a large family of compounds with formula [Ba(Co,Ga)O 3-delta] n [BaCo 8O 11]. In the latter, both sublattices contain triangular networks derived from the hexagonal perovskite and the spinel structure. Among the hexagonal perovskite, the Ca 3Co 2O 6 crystals give clear evidence where the coupling of charges and spins is at the origin of a magnetocapacitance effect. In particular, the ferrimagnetic to ferromagnetic transition, with a one-third plateau on the M( H) curve characteristic of triangular magnetism, is accompanied by a peak in the dielectric constant. A second class of cobaltites is the focus of much interest. Their 2D structure, containing CoO 2 planes isostructural to a CdI 2 slice that are stacked in an incommensurate way with rock salt type layers, is referred to misfit cobaltite. The 2D triangular network of edge-shared CoO 6 octahedra is believed to be responsible for large values of the Seebeck coefficient and low electrical resistivity. A clear relationship between the structuresincommensurability ratiosand the electronic properties is evidenced, showing that the charge carrier concentration can be tuned via the control of the ionic radius of the cations in the separating layers.
ABSTRACT
A 59Co NMR study of CoO2, the x=0 end member of AxCoO2 (A=Na,Li,...) cobaltates, reveals a metallic ground state, though with clear signs of strong electron correlations: low-energy spin fluctuations develop at wave vectors q not equal to 0 and a crossover to a Fermi-liquid regime occurs below a characteristic temperature T* approximately 7 K. Despite some uncertainty over the exact cobalt oxidation state in this material, the results show that electronic correlations are revealed as x is reduced below 0.3. The data are consistent with NaxCoO2 being close to the Mott transition in the x-->0 limit.
ABSTRACT
Samples of the low-doped manganite La(0.875)Sr(0.125-x)Ca(x)MnO(3) (0≤x≤0.125) have been synthesized and the effect on the structural, magnetic and transport properties of decreasing the tolerance factor by replacing larger Sr(2+) ions with smaller Ca(2+) ions are reported. For samples with x≥0.0625, a concentration (x) dependent structural transition (rhombohedral ([Formula: see text]) to orthorhombic (Pnma)) has been detected at room temperature and the Curie temperature T(C) is found to decrease with increased Ca doping level. For samples with x≤0.0625, a narrow metallic region exists and the corresponding insulator to metal transition temperature T(MI) decreases with increasing Ca content, i.e. decreasing tolerance factor. In the paramagnetic region, x dependent crossover from Mott variable range hopping (Mott-VRH) to Shklovskii-Efros variable range hopping (SE-VRH) occurs as the Ca content increases. The thermoelectric power (TEP) of the samples increases substantially, varying inversely with the tolerance factor. These results are analysed from the consideration of increased bending of the Mn-O-Mn bond with the decrease of the average ionic radius of the A-site element [Formula: see text] and the tolerance factor t, which causes narrowing of the bandwidth, decrease of mobility of e(g) electrons and weakening of the double exchange (DE) interaction associated with the substitution of Ca.
ABSTRACT
We investigate both thermoelectric and thermodynamic properties of the misfit cobalt oxide [Bi1.7Co0.3Ca2O4]RS0.6CoO2. A large negative magnetothermopower is found to scale with both magnetic field and temperature, revealing a significant spin entropy contribution to thermoelectric properties giving rise to a constant S0 approximately 60 microV K-1. Specific heat measurements allow us to determine an enhanced electronic part with gamma approximately 50 mJ (mol K2)-1 attesting to strong correlations. Thereby, the comparison between cobaltites and other materials reveals a universal behavior of the thermopower slope as a function of gamma, testifying to a purely electronic origin. This potentially generic scaling behavior suggests here that the high room temperature value of the thermopower in misfit cobalt oxides results from the addition of a spin entropy contribution to an enlarged electronic one.