bluuebunny/crossref_metadata_2025 huggingface dataset:
The Caulobacter crescentus Homolog of DnaA (HdaA) Also Regulates the Proteolysis of the Replication Initiator Protein DnaA
Authors: Wargachuk Richard , Marczynski Gregory T.
Published: September 2015

It is not known how diverse bacteria regulate chromosome replication. Based on
Escherichia coli
studies, DnaA initiates replication and the homolog of DnaA (Hda) inactivates DnaA using the RIDA (
r
egulatory
i
nactivation of
D
na
A
) mechanism that thereby prevents extra chromosome replication cycles. RIDA may be widespread, because the distantly related
Caulobacter crescentus
homolog HdaA also prevents extra chromosome replication (J. Collier and L. Shapiro, J Bacteriol 191:5706–5715, 2009,
http://dx.doi.org/10.1128/JB.00525-09
). To further study the HdaA/RIDA mechanism, we created a
C. crescentus
strain that shuts off
hdaA
transcription and rapidly clears HdaA protein. We confirm that HdaA prevents extra replication, since cells lacking HdaA accumulate extra chromosome DNA. DnaA binds nucleotides ATP and ADP, and our results are consistent with the established
E. coli
mechanism whereby Hda converts active DnaA-ATP to inactive DnaA-ADP. However, unlike
E. coli
DnaA,
C. crescentus
DnaA is also regulated by selective proteolysis.
C. crescentus
cells lacking HdaA reduce DnaA proteolysis in logarithmically growing cells, thereby implicating HdaA in this selective DnaA turnover mechanism. Also, wild-type
C. crescentus
cells remove all DnaA protein when they enter stationary phase. However, cells lacking HdaA retain stable DnaA protein even when they stop growing in nutrient-depleted medium that induces complete DnaA proteolysis in wild-type cells. Additional experiments argue for a distinct HdaA-dependent mechanism that selectively removes DnaA prior to stationary phase. Related freshwater
Caulobacter
species also remove DnaA during entry to stationary phase, implying a wider role for HdaA as a novel component of programed proteolysis.

IMPORTANCE
Bacteria must regulate chromosome replication, and yet the mechanisms are not completely understood and not fully exploited for antibiotic development. Based on
Escherichia coli
studies, DnaA initiates replication, and the homolog of DnaA (Hda) inactivates DnaA to prevent extra replication. The distantly related
Caulobacter crescentus
homolog HdaA also regulates chromosome replication. Here we unexpectedly discovered that unlike the
E. coli
Hda, the
C. crescentus
HdaA also regulates DnaA proteolysis. Furthermore, this HdaA proteolysis acts in logarithmically growing and in stationary-phase cells and therefore in two very different physiological states. We argue that HdaA acts to help time chromosome replications in logarithmically growing cells and that it is an unexpected component of the programed entry into stationary phase.
ArcD1 and ArcD2 Arginine/Ornithine Exchangers Encoded in the Arginine Deiminase Pathway Gene Cluster of Lactococcus lactis
Authors: Noens Elke E. E. , Kaczmarek Michał B. , Żygo Monika , Lolkema Juke S.
Published: September 2015

The arginine deiminase (ADI) pathway gene cluster in
Lactococcus lactis
contains two copies of a gene encoding an
l
-arginine/
l
-ornithine exchanger, the
arcD1
and
arcD2
genes. The physiological function of ArcD1 and ArcD2 was studied by deleting the two genes. Deletion of
arcD1
resulted in loss of the growth advantage observed in the presence of high
l
-arginine in different growth media. Uptake of
l
-arginine and
l
-ornithine by resting cells was reduced to the low level observed for an ArcD1/ArcD2 double deletion mutant. Deletion of the
arcD2
gene did not affect the growth enhancement, and uptake activities were slightly reduced. Nevertheless, recombinant expression of ArcD2 in the ArcD1/ArcD2 double mutant did recover the growth advantage. Kinetic characterization of ArcD1 and ArcD2 showed high affinities for both
l
-arginine and
l
-ornithine (

K
m

in the micromolar range). A difference between the two transporters was the significantly lower affinity of ArcD2 for the cationic amino acids
l
-ornithine,
l
-lysine, and
l
-histidine. In contrast, the affinity of ArcD2 was higher for the neutral amino acid
l
-alanine. Moreover, ArcD2 efficiently translocated
l
-alanine, while ArcD1 did not. Both transporters revealed affinities in the mM range for agmatine, cadaverine, histamine, and putrescine. These amines bind but are not translocated. It is concluded that ArcD1 is the main
l
-arginine/
l
-ornithine exchanger in the ADI pathway and that ArcD2 is not functionally expressed in the media used. ArcD2 is proposed to function together with the
arcT
gene that encodes a putative transaminase and is found adjacent to the
arcD2
gene.

IMPORTANCE
The arginine deiminase (ADI) pathway gene cluster in
Lactococcus lactis
contains two copies of a gene encoding an
l
-arginine/
l
-ornithine exchanger, the
arcD1
and
arcD2
genes. The physiological function of ArcD1 and ArcD2 was studied by deleting the two genes. It is concluded that ArcD1 is the main
l
-arginine/
l
-ornithine exchanger in the ADI pathway. ArcD2 is proposed to function as a
l
-arginine/
l
-alanine exchanger in a pathway together with the
arcT
gene, which is found adjacent to the
arcD2
gene in the ADI gene cluster.
A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis
Authors: Wu Genfu , Wan Fen , Fu Huihui , Li Ning , Gao Haichun
Published: September 2015

Hydrogen sulfide (H
2
S), well known for its toxic properties, has recently become a research focus in bacteria, in part because it has been found to prevent oxidative stress caused by treatment with some antibiotics. H
2
S has the ability to scavenge reactive oxygen species (ROS), thus preventing oxidative stress, but it is also toxic, leading to conflicting reports of its effects in different organisms. Here, with
Shewanella oneidensis
as a model, we report that the effects of H
2
S on the response to oxidative stress are time dependent. When added simultaneously with H
2
O
2
, H
2
S promoted H
2
O
2
toxicity by inactivating catalase, KatB, a heme-containing enzyme involved in H
2
O
2
degradation. Such an inhibitory effect may apply to other heme-containing proteins, such as cytochrome
cbb
3
oxidase. When H
2
O
2
was supplied 20 min or later after the addition of H
2
S, the oxidative-stress-responding regulator OxyR was activated, resulting in increased resistance to H
2
O
2
. The activation of OxyR was likely triggered by the influx of iron, a response to lowered intracellular iron due to the iron-sequestering property of H
2
S. Given that
Shewanella
bacteria thrive in redox-stratified environments that have abundant sulfur and iron species, our results imply that H
2
S is more important for bacterial survival in such environmental niches than previously believed.

IMPORTANCE
Previous studies have demonstrated that H
2
S is either detrimental or beneficial to bacterial cells. While it can act as a growth-inhibiting molecule by damaging DNA and denaturing proteins, it helps cells to combat oxidative stress. Here we report that H
2
S indeed has these contrasting biological functions and that its effects are time dependent. Immediately after H
2
S treatment, there is growth inhibition due to damage of heme-containing proteins, at least to catalase and cytochrome
c
oxidase. In contrast, when added a certain time later, H
2
S confers an enhanced ability to combat oxidative stress by activating the H
2
O
2
-responding regulator OxyR. Our data reconcile conflicting observations about the functions of H
2
S.
A critical appraisal of clinical trials conducted and subsequent drug approvals in India and South Africa
Authors: Limaye Dnyanesh , Langer Janka Marisa , Rühling Tjorben , Fortwengel Gerhard
Published: September 2015

Objectives

To assess the relation between the number of clinical trials conducted and respective new drug approvals in India and South Africa.

Design

Construction and analysis of a comprehensive database of completed randomised controlled clinical trials based on clinicaltrials.gov from 1 January 2005 to 31 December 2010 and drug approval data from 2006 until 2013 for India and South Africa.

Setting

USA, the EU, India and South Africa.

Main outcome measures

Percentage of completed randomised clinical trials for an Investigational Medicinal Product (IMP) leading to new drug approval in India and South Africa.

Results

A total of 622 eligible randomised controlled trials were identified as per search criteria for India and South Africa. Clustering them for the same sponsor and the same Investigational New Drug (IND) resulted in 453 eligible trials, that is, 224 for India and 229 for South Africa. The distribution of the market application approvals between the EU/USA as well as India and South Africa revealed that out of clinical trials with the participation of test centres in India and/or South Africa, 39.6% (India) clinical trials and 60.1% (South Africa) clinical trials led to market authorisation in the EU/USA without a New Drug Application (NDA) approval in India or South Africa.

Conclusions

Despite an increase in clinical trial activities, there is a clear gap between the number of trials conducted and market availability of these new drugs in India and South Africa. Drug regulatory authorities, investigators, institutional review boards and patient groups should direct their efforts to ensuring availability of new drugs in the market that have been tested and researched on their population.
Can we influence the epidemiology of dementia? Perspectives from population-based studies
Authors: Birdi Ratika , Stephan Blossom Christa Maree , Robinson Louise , Davis Daniel
Published: September 2015

The worldwide prevalence of dementia is predicted to rise significantly in the next three decades. However, these projections have not taken into account the role of modifiable risk factors and whether any prevention strategies might influence the predicted trend. Attempts at pharmacological disease modification have largely been disappointing, and the difficulties in conducting dementia trials are reviewed here. In contrast, recent population studies in high-income countries suggest that the epidemiology may be changing with a possible decline in incident dementia, or even a reduction in age-specific prevalence. Therefore, efforts to develop public health interventions may prove to be the more successful approach to addressing dementia at a societal level.
Consequences of seasonal variation in reservoir water level for predatory fishes: linking visual foraging and prey densities
Authors: Klobucar Stephen L. , Budy Phaedra
Published: September 2015

In reservoirs, seasonal drawdown can alter the physical environment and may influence predatory fish performance. We investigated the performance of lake trout (Salvelinus namaycush) in a western reservoir by coupling field measurements with visual foraging and bioenergetic models at four distinct states (early summer, mid-summer, late summer, and fall). The models suggested that lake trout prey, juvenile kokanee (Oncorhynchus nerka), are limited seasonally by suitable temperature and dissolved oxygen. Accordingly, prey densities were greatest in late summer when reservoir volume was lowest and fish were concentrated by stratification. Prey encounter rates (up to 68 fish·day−1) and predator consumption are also predicted to be greatest during late summer. However, our models suggested that turbidity negatively correlates with prey detection and consumption across reservoir states. Under the most turbid conditions, lake trout did not meet physiological demands; however, during less turbid periods, predator consumption reached maximum bioenergetic efficiency. Overall, our findings demonstrate that rapid reservoir fluctuations and associated abiotic conditions can influence predator–prey interactions, and our models describe the potential impacts of water level fluctuation on valuable sport fishes.
Test of the temperature difference model predicting masting behavior
Authors: Kon Hirokazu , Saito Hideki
Published: September 2015

The differential temperature (ΔT) model, based on the assumption that masting plants respond to the difference in the temperatures during the growing seasons 1 and 2 years prior to seed production, has recently been proposed to explain the proximate factor of masting. In this study, we used a 28-year series of data on pollen cone and seed production in Cryptomeria japonica D. Don in Japan and compared several models based on temperatures and resources to test whether ΔT acts as a cue or is a proxy for resource limitation. Of all the models tested, models including ΔT, previous summer absolute temperature Tn–1, and reproduction in the previous year provided the best fit. The number of pollen cones and seeds produced was proportional to the difference in the mean daily maximum temperature during June to August between the preceding two years. In addition, to test whether the double mast events in consecutive years was less common than consecutive warm summers, we used our dataset and 12 datasets of pollen dispersal of 17 years or longer of C. japonica in Japan. Although consecutive warm summers occurred in 4.4% of pairs, double mast events occurred in 1.0%. The ΔT model was a considerably better predictor of the rare phenomenon of double mast events, which occur only after a specific sequence of cold–moderate–hot absolute summer temperatures. Thus, ΔT acts as cue for masting in C. japonica.
Populus tremuloides stands continue to deteriorate after drought-incited sudden aspen decline
Authors: Worrall James J. , Keck Andrew G. , Marchetti Suzanne B.
Published: September 2015

Reports of forest damage have increased with the frequency of climatic extremes, but longer term impacts of such events on population dynamics of forest trees are generally unknown. Incited by the turn-of-the-century drought, sudden aspen decline (SAD) damaged 535 000 ha of Populus tremuloides Michx. in the Southern Rockies ecoregion of western North America. Although spread of the disease stopped in about 2009, most of the affected stands continued to deteriorate. Remeasurement of plots in southwestern Colorado showed that, since the peak of the epidemic, live basal area in sick plots decreased by an additional 28% to only 38% of that in healthy plots. Sick plots had much more recent damage than healthy plots, with almost three times as much recently dead basal area, over twice the density of recently dead trees, and almost four times as much recent crown loss. The important contributing agents in SAD were still active in sick stands in 2013. Density of small regeneration showed opposite trends, increasing in healthy plots and decreasing in sick plots. Timely regeneration treatments may be needed in some such stands to facilitate recovery. In addition to acute damage from climatic extremes, long-term decline diseases like SAD will likely be a common signature of forest damage from climate change.
THE DETERMINANTS OF TOTAL FACTOR PRODUCTIVITY IN THE MALAYSIAN AUTOMOTIVE INDUSTRY: ARE GOVERNMENT POLICIES UPGRADING TECHNOLOGICAL CAPACITY?
Authors: OTSUKA KOZO , NATSUDA KAORU
Published: September 2015

This paper examines the determinants of total factor productivity (TFP) in the Malaysian automotive industry, focusing on the effectiveness of government policies. Our panel data analysis shows that the productivity of the automotive industry in Malaysia highly depends on the technology embodied within imports. Government policies have not contributed to the technological upgrading of the industry. The policies to protect the domestic producers from international competition and to favor bumiputra firms seem to have adverse impacts on productivity.
UNIT ROOT TESTS IN THE PRESENCE OF MULTIPLE BREAKS IN VARIANCE
Authors: JEONG SOO-BIN , KIM BONG-HWAN , KIM TAE-HWAN , MOON HYUNG-HO
Published: September 2015

Spurious rejections of the standard Dickey–Fuller (DF) test caused by a single variance break have been reported and some solutions to correct the problem have been proposed in the literature. Kim et al. (2002) put forward a correctly-sized unit root test robust to a single variance break, called the KLN test. However, there can be more than one break in variance in time series data as documented in Zhou and Perron (2008), so allowing only one break can be too restrictive. In this paper, we show that multiple breaks in variance can generate spurious rejections not only by the standard DF test but also by the KLN test. We then propose a bootstrap-based unit root test that is correctly-sized in the presence of multiple breaks in variance. Simulation experiments demonstrate that the proposed test performs well regardless of the number of breaks and the location of the breaks in innovation variance.
WELFARE EFFECTS OF DOWNSTREAM MERGERS AND UPSTREAM MARKET CONCENTRATION
Authors: FAULI-OLLER RAMON , SANDONIS JOEL
Published: September 2015

We consider a dominant upstream firm selling an input to several downstream firms through observable, non-discriminatory two-part tariff contracts. Downstream firms can alternatively buy the input from a less efficient source of supply. In this setting, we analyze the relationship between the competitive effects of downstream mergers and the level of concentration at the upstream level. We show that a downstream merger leads to lower wholesale prices. This translates into lower final prices only when the upstream market is sufficiently concentrated. In this case, a downstream merger tends to be both procompetitive and profitable.
Magnetic field, frequency and temperature dependence of complex conductance of ultrathin La1.65Sr0.45CuO4∕La2CuO4 films and the organic superconductors κ-(BEDT-TTF)2Cu[N(CN)2]Br
Authors: Gasparov V. A. , He Xi , Dubuis G. , Pavuna D. , Kushch N. D. , Yagubskii E. B. , Schlueter J. A. , Bozovic I.
Published: September 2015

We used atomic-layer molecular beam epitaxy (ALL-MBE) to synthesize bilayer films of a cuprate metal ([Formula: see text], LSCO) and a cuprate insulator ([Formula: see text], LCO), in which interface superconductivity occurs in a layer that is just one-half unit cell thick. We have studied the magnetic field and temperature dependence of the complex sheet conductance, [Formula: see text], of these films, and compared them to [Formula: see text]-(BEDT-TTF)[Formula: see text] single crystals. The magnetic field [Formula: see text] was applied both parallel and perpendicular to the 2D conducting layers. Experiments have been carried out at frequencies between 23 kHz and 50 MHz using either two-coil mutual inductance technique, or the LC resonators with spiral or rectangular coils. The real and the imaginary parts of the mutual-inductance [Formula: see text] between the coil and the sample were measured and converted to complex conductivity. For [Formula: see text] perpendicular to the conducting layers, we observed almost identical behavior in both films and [Formula: see text]-Br single crystals: (i) the transition onset in the inductive response, [Formula: see text](T) occurs at a temperature lower by 2 K than in [Formula: see text], (ii) this shift is almost constant with magnetic field up to 8 T; (iii) the vortex diffusion constant [Formula: see text] is exponential due to pinning of vortex cores. These results can be described by the extended dynamic theory of the Berezinski–Kosterlitz–Thouless (BKT) transition and dynamics of bound vortex–antivortex pairs with short separation lengths.
Investigations of the defect structure for Cu2+ in LaSrGa0.995Cu0.005O4 Ceramics
Authors: Ding C. C. , Wu S. Y. , Cheng Y. K. , Zhang L. J.
Published: September 2015

The defect structure and spin Hamiltonian parameters ([Formula: see text] factors [Formula: see text], [Formula: see text] and the hyperfine structure constants [Formula: see text] and [Formula: see text]) for the tetragonal [Formula: see text] in [Formula: see text] ceramics are theoretically studied from the perturbation formulas of these parameters for a [Formula: see text] ion in a tetragonally elongated octahedron. The impurity [Formula: see text] center exhibits the larger relative tetragonal elongation ratio [Formula: see text] than that [Formula: see text] of the host [Formula: see text] site due to the Jahn–Teller effect. The relationship between the [Formula: see text] anisotropy [Formula: see text] [Formula: see text] and the local tetragonal distortion is analyzed. The present studies would be helpful to the understandings of delocalization of the [Formula: see text] [Formula: see text] orbitals under tetragonal elongation distortion and its role in superconductivity of oxygen cuprates.
Bioelectrical effects of mechanical feedbacks in a strongly coupled cardiac electro-mechanical model
Authors: Colli Franzone Piero , Pavarino Luca F. , Scacchi Simone
Published: September 2015

The aim of this work is to investigate by means of numerical simulations the effects of myocardial deformation due to muscle contraction on the bioelectrical activity of the cardiac tissue. The three-dimensional electro-mechanical model considered consists of the following four components: the quasi-static orthotropic finite elasticity equations for the deformation of the cardiac tissue; the active tension model for the intracellular calcium dynamics and cross-bridge binding; the orthotropic Bidomain model for the electrical current flow through the tissue; the membrane model of the cardiac myocyte, including stretch-activated currents (I SAC ). In order to properly take into account cardiac mechanical feedbacks, the electrical current flow is described in a strongly coupled framework by the Bidomain model on the deformed tissue. We then derive a novel formulation of the Bidomain model in the reference configuration, with complete mechanical feedbacks affecting not only the conductivity tensors but also a convective term depending on the velocity of the deformation. The numerical simulations are based on our finite element parallel solver, which employs both Multilevel Additive Schwarz preconditioners for the solution of linear systems arising from the discretization of the Bidomain equations and Newton–Krylov-Algebraic Multigrid methods for the solution of nonlinear systems arising from the discretization of the finite elasticity equations. The results have shown that: (i) the I SAC current prolongs action potential duration (APD) of about 10–15 ms; (ii) the inclusion into the model of both I SAC current and the convective term reduces the dispersion of repolarization of about 7% (from 139 to 129 ms) and increases the dispersion of APD about three times (from 13 to 45 ms). These effects indicate that mechanical feedbacks might influence arrhythmogenic mechanisms when combined with pathological substrates.
Critical thresholds in 1D Euler equations with non-local forces
Authors: Carrillo José A. , Choi Young-Pil , Tadmor Eitan , Tan Changhui
Published: September 2015

We study the critical thresholds for the compressible pressureless Euler equations with pairwise attractive or repulsive interaction forces and non-local alignment forces in velocity in one dimension. We provide a complete description for the critical threshold to the system without interaction forces leading to a sharp dichotomy condition between global-in-time existence or finite-time blowup of strong solutions. When the interaction forces are considered, we also give a classification of the critical thresholds according to the different type of interaction forces. We also remark on global-in-time existence when the repulsion is modeled by the isothermal pressure law.
Design of a novel quantum reversible ternary up-counter
Authors: Houshmand Pouran , Haghparast Majid
Published: September 2015

Reversible logic has been recently considered as an interesting and important issue in designing combinational and sequential circuits. The combination of reversible logic and multi-valued logic can improve power dissipation, time and space utilization rate of designed circuits. Only few works have been reported about sequential reversible circuits and almost there are no paper exhibited about quantum ternary reversible counter. In this paper, first we designed 2-qutrit and 3-qutrit quantum reversible ternary up-counters using quantum ternary reversible T-flip-flop and quantum reversible ternary gates. Then we proposed generalized quantum reversible ternary n-qutrit up-counter. We also introduced a new approach for designing any type of n-qutrit ternary and reversible counter. According to the results, we can conclude that applying second approach quantum reversible ternary up-counter is better than the others.
Special generalized densities and propagators: A geometric account
Authors: Canarutto Daniel
Published: September 2015

Starting from a short review of spaces of generalized sections of vector bundles, we give a concise systematic description, in precise geometric terms, of Leray densities, principal value densities, propagators and elementary solutions of field equations in flat spacetime. We then sketch a partly original geometric presentation of free quantum fields and show how propagators arise from their graded commutators in the boson and fermion cases.
Revisiting Clustered Microarchitecture for Future Superscalar Cores
Authors: Michaud Pierre , Mondelli Andrea , Seznec André
Published: September 2015

During the past 10 years, the clock frequency of high-end superscalar processors has not increased. Performance keeps growing mainly by integrating more cores on the same chip and by introducing new instruction set extensions. However, this benefits only some applications and requires rewriting and/or recompiling these applications. A more general way to accelerate applications is to increase the IPC, the number of instructions executed per cycle. Although the focus of academic microarchitecture research moved away from IPC techniques, the IPC of commercial processors was continuously improved during these years.

We argue that some of the benefits of technology scaling should be used to raise the IPC of future superscalar cores further. Starting from microarchitecture parameters similar to recent commercial high-end cores, we show that an effective way to increase the IPC is to allow the out-of-order engine to issue more micro-ops per cycle. But this must be done without impacting the clock cycle. We propose combining two techniques: clustering and register write specialization. Past research on clustered microarchitectures focused on narrow issue clusters, as the emphasis at that time was on allowing high clock frequencies.

Instead, in this study, we consider wide issue clusters, with the goal of increasing the IPC under a constant clock frequency. We show that on a wide issue dual cluster, a very simple steering policy that sends 64 consecutive instructions to the same cluster, the next 64 instructions to the other cluster, and so forth, permits tolerating an intercluster delay of three cycles. We also propose a method for decreasing the energy cost of sending results from one cluster to the other cluster.
Demo hour
Authors: Elblaus Ludvig , Tsaknaki Vasiliki , Lewandowski Vincent , Bresin Roberto , Hwang Sungjae , Song John , Gim Junghyeon , Griggio Carla , Leiva Germán , Romero Mario , Sweeney David , Regan Tim , Helmes John , Vlachokyriakos Vasillis , Lindley Siân , Taylor Alex
Published: September 2015

Interactivity is a unique forum of the ACM CHI Conference that showcases hands-on demonstrations, novel interactive technologies, and artistic installations. At CHI 2015 in Seoul we hosted more than 30 exhibits, including an invited digital interactive art exhibit. Interactivity highlights the diverse group of computer scientists, sociologists, designers, psychologists, artists, and many more who make up the CHI community.
Julie R. Williamson and Juhyun Eune, CHI 2015 Interactivity Chairs
Exploring personal data for public good research
Authors: Bietz Matthew J. , Bloss Cinnamon , Godino Job , Patrick Kevin
Published: September 2015

This forum is dedicated to personal health in all its many facets: decision-making, goal setting, celebration, discovery, reflection, and coordination, among others. We look at innovations in interactive technologies and how they help address current critical healthcare challenges.
--- Gillian R. Hayes, Editor
Laser cutters
Authors: Mueller Stefanie , Baudisch Patrick
Published: September 2015

Envisioning, designing, and implementing the user interface require a comprehensive understanding of interaction technologies. In this forum we scout trends and discuss new technologies with the potential to influence interaction design.
--- Albrecht Schmidt, Editor
A progressive assessment strategy improves student learning and perceived course quality in undergraduate physiology
Authors: Saint D. A. , Horton D. , Yool A. , Elliott A.
Published: September 2015

In 2010, second-year physiology ( n = 165) had a traditional single 3-h end-of-semester exam. To provide diagnostic feedback earlier, for students enrolled in 2011 ( n = 128), we incorporated an in-class exam at 3 wk in addition to the final exam. Based on initial analysis and positive student comments, for the 2012 cohort ( n = 148), we expanded this to incorporate four 1-h in-class exams every 3 wk plus a short final integrative exam. Average scores from exams and questionnaires (student evaluations of learning and teaching, 10 questions) were compared among 2010, 2011, and 2012 cohorts. We also compared scores in the practical component of the course, which had a constant format for all cohorts. Data are given as means ± SD; statistical analyses were done with unpaired two-way Students t-tests. From 2010 to 2012, there was a significant improvement in total exam scores (59.7 ± 15.8 vs. 68.6 ± 14.2, P < 0.001) but no significant change in total practical scores (72.3 ± 9.0 vs. 74.4 ± 10.2, P = 0.05), indicating that the rise in exam score was not due to higher academic abilities of the 2012 cohort. Overall mean student evaluation of learning and teaching responses (4.9 ± 0.4 vs. 5.3 ± 0.3, P = 0.015) and overall percent broad agreement (66.0 ± 8.0 vs. 79.2 ± 7.5, P = 0.003) indicated a significant improvement in student satisfaction. In conclusion, both learning outcome and perceived course quality were enhanced by the increased frequency of examinations, possibly by promoting consistent student study habits.
Students integrate knowledge acquisition and practical work in the laboratory
Authors: Agüera E. I. , Sánchez-Hermosín P. , Díz-Pérez J. , Tovar P. , Camacho R. , Escribano B. M.
Published: September 2015

The aim of the present work was to transfer a wider concept of teamwork and self-learning to the laboratory, encouraging students' capabilities when seeking, acquiring, and processing knowledge. This educational innovation was carried out with a total of 38 students (fourth year of degree in Biology) in the area of physiology (Advances in Reproduction course) at University of Córdoba in Córdoba, Spain. The design of the project's application methodology consisted of establishing a way in which problems would be tackled in the practical classes. For this purpose, the different tasks were set up so that students could relate them to the concepts learned in the theory classes. On the first day of class, the project was presented to the students. Groups of two to three students worked in the laboratory and set up an outline of the protocol of the practical work that they had done. This outline was performed individually and sent to the lecturers through a learning management system (Moodle). The teachers gave feedback and assessed student submissions. Upon finishing the course, students completed a survey. The project-based learning method promotes practical self-learning on the part of students. This methodology demonstrated to us that it stimulates a critical and self-critical capacity in students, both individually and in groups, and that writing didactic practical material helped students to enhance their theory knowledge. The experiment was a success in view of the scores obtained upon finishing the subject.
A simple device for measuring static compliance of lung-thorax combine
Authors: Sircar Sabyasachi
Published: September 2015

Explaining the concept of lung compliance remains a challenge to the physiology teacher because it cannot be demonstrated easily in human subjects and all attempts until now have used only simulation models. A simple device is described in the present article to measure the compliance of the “lung-thorax” combine in human subjects with the caveat that what is recorded is not “lung” compliance and the data generated are of little clinical use. The device comprises a spirometer, a manometer, a mouthpiece, and interconnecting tubes guarded with stopcocks.
“Heart Shots”: a classroom activity to instigate active learning
Authors: Abraham Reem Rachel , Vashe Asha , Torke Sharmila
Published: September 2015

The present study aimed to provide undergraduate medical students at Melaka Manipal Medical College (Manipal Campus), Manipal University, in Karnataka, India, an opportunity to apply their knowledge in cardiovascular concepts to real-life situations. A group activity named “Heart Shots” was implemented for a batch of first-year undergraduate students ( n = 105) at the end of a block (teaching unit). Students were divided into 10 groups each having 10–11 students. They were requested to make a video/PowerPoint presentation about the application of cardiovascular principles to real-life situations. The presentation was required to be of only pictures/photos and no text material, with a maximum duration of 7 min. More than 95% of students considered that the activity helped them to apply their knowledge in cardiovascular concepts to real-life situations and understand the relevance of physiology in medicine and to revise the topic. More than 90% of students agreed that the activity helped them to apply their creativity in improving their knowledge and to establish a link between concepts rather than learning them as isolated facts. Based on the feedback, we conclude that the activity was student centered and that it facilitated learning.
Exploring student preferences with a Q-sort: the development of an individualized renal physiology curriculum
Authors: Roberts John K. , Hargett Charles W. , Nagler Alisa , Jakoi Emma , Lehrich Ruediger W.
Published: September 2015

Medical education reform is underway, but the optimal course for change has yet to be seen. While planning for the redesign of a renal physiology course at the Duke School of Medicine, the authors used a Q-sort survey to assess students' attitudes and learning preferences to inform curricular change. The authors invited first-year medical students at the Duke School of Medicine to take a Q-sort survey on the first day of renal physiology. Students prioritized statements related to their understanding of renal physiology, learning preferences, preferred course characteristics, perceived clinical relevance of renal physiology, and interest in nephrology as a career. By-person factor analysis was performed using the centroid method. Three dominant factors were strongly defined by learning preferences: “readers” prefer using notes, a textbook, and avoid lectures; “social-auditory learners” prefer attending lectures, interactivity, and working with peers; and “visual learners” prefer studying images, diagrams, and viewing materials online. A smaller, fourth factor represented a small group of students with a strong predisposition against renal physiology and nephrology. In conclusion, the Q-sort survey identified and then described in detail the dominant viewpoints of our students. Learning style preferences better classified first-year students rather than any of the other domains. A more individualized curriculum would simultaneously cater to the different types of learners in the classroom.
Effect of peer instruction on the likelihood for choosing the correct response to a physiology question
Authors: Relling Alejandro E. , Giuliodori Mauricio J.
Published: September 2015

The aims of the present study were to measure the effects of individual answer (correct vs. incorrect), individual answer of group members (no vs. some vs. all correct), self-confidence about the responses (low vs. mid vs. high), sex (female vs. male students), and group size (2–4 students) on the odds for change and for correctness after peer instruction in a veterinary physiology course ( n = 101 students). Data were assessed by multivariable logistic regression analysis. The likelihood for change after peer instruction increased when the confidence on an individual answer was low ( P < 0.01), when the answer was incorrect ( P < 0.01), and when group members had different responses ( P < 0.01). The likelihood for correctness after peer instruction increased when the confidence in group answers was high ( P < 0.01), when the individual answer was correct ( P < 0.01), and when at least one of the group members had the correct response ( P < 0.01). After peer discussion, more changes were from incorrect to correct responses than vice versa (72% vs. 28%, P < 0.01). Changes to correct answers occurred after discussion with peers having both the correct individual response (76% of times) and also the incorrect individual answer (24% of times). In conclusion, the benefits of peer instruction are due to students having correct answers generally prevail in discussions. Also, students who all have incorrect answers can get the correct answer through debate and discussion.
Intellectual development is positively related to intrinsic motivation and course grades for female but not male students
Authors: Cortright Ronald N. , Lujan Heidi L. , Cox Julie H. , Cortright Maria A. , Langworthy Brandon M. , Petta Lorene M. , Tanner Charles J. , DiCarlo Stephen E.
Published: September 2015

We hypothesized that the intellectual development of students, i.e., their beliefs about the nature of knowledge and learning, affects their intrinsic motivation and class performance. Specifically, we hypothesized that students with low intellectual development (i.e., the naive beliefs that knowledge is simple, absolute, and certain) have low intrinsic motivation and low class performance, whereas students with high intellectual development (i.e., more sophisticated beliefs that knowledge is complex, tentative, and evolving) have high intrinsic motivation and class performance. To test this hypothesis, we administered the Learning Context Questionnaire to measure intellectual development. In addition, we administered the Intrinsic Motivation Inventory to assess our students' intrinsic motivation. Furthermore, we performed regression analyses between intellectual development with both intrinsic motivation and class performance. The results document a positive relationship among intellectual development, intrinsic motivation, and class performance for female students only. In sharp contrast, there was a negative relationship between intellectual development, intrinsic motivation, and class performance for male students. The slope comparisons documented significant differences in the slopes relating intellectual development, intrinsic motivation, and class performance between female and male students. Thus, female students with more sophisticated beliefs that knowledge is personally constructed, complex, and evolving had higher intrinsic motivation and class performance. In contrast, male students with the naive beliefs that the structure of knowledge is simple, absolute, and certain had higher levels of intrinsic motivation and class performance. The results suggest that sex influences intellectual development, which has an effect on intrinsic motivation for learning a specific topic.
Understanding diffusion theory and Fick's law through food and cooking
Authors: Zhou Larissa , Nyberg Kendra , Rowat Amy C.
Published: September 2015

Diffusion is critical to physiological processes ranging from gas exchange across alveoli to transport within individual cells. In the classroom, however, it can be challenging to convey the concept of diffusion on the microscopic scale. In this article, we present a series of three exercises that use food and cooking to illustrate diffusion theory and Fick's first law. These exercises are part of a 10-wk undergraduate course that uses food and cooking to teach fundamental concepts in physiology and biophysics to students, including nonscience majors. Consistent demonstration of practical applications in a classroom setting has the potential to fundamentally change how students view the role of science in their lives (15).
The Healthy Heart: Lessons from Nature's Elite Athletes
Authors: Williams Terrie M. , Bengtson Penni , Steller Diana L. , Croll Donald A. , Davis Randall W.
Published: September 2015

The incidence of cardiovascular disease in humans is more than three times that of many wild and domestic mammals despite nearly identical heart morphologies and responses to exercise. A survey of mammalian species from 0.002-kg shrews to 43,000-kg whales shows that the human heart is more dog-like than cat-like and that neither body size nor longevity accounts for the relative vulnerability to cardiovascular disease. Rather, a major difference is daily activity patterns, which may underlie the comparatively healthy hearts of wild mammals.
Oxygen Sensing and Homeostasis
Authors: Prabhakar Nanduri R. , Semenza Gregg L.
Published: September 2015

The discovery of carotid bodies as sensory receptors for detecting arterial blood oxygen levels, and the identification and elucidation of the roles of hypoxia-inducible factors (HIFs) in oxygen homeostasis have propelled the field of oxygen biology. This review highlights the gas-messenger signaling mechanisms associated with oxygen sensing, as well as transcriptional and non-transcriptional mechanisms underlying the maintenance of oxygen homeostasis by HIFs and their relevance to physiology and pathology.
Intermediaries in Trust: Indirect Reciprocity, Incentives, and Norms
Authors: Bravo Giangiacomo , Squazzoni Flaminio , Takács Károly
Published: September 2015

Any trust situation involves a certain amount of risk for trustors that trustees could abuse. In some cases, intermediaries exist who play a crucial role in the exchange by providing reputational information. To examine under what conditions intermediary opinion could have a positive impact on cooperation, we designed two experiments based on a modified version of the investment game where intermediaries rated the behaviour of trustees under various incentive schemes and different role structures. We found that intermediaries can increase trust if there is room for indirect reciprocity between the involved parties. We also found that the effect of monetary incentives and social norms cannot be clearly separable in these situations. If properly designed, monetary incentives for intermediaries can have a positive effect. On the one hand, when intermediary rewards are aligned with the trustor’s interest, investments and returns tend to increase. On the other hand, fixed monetary incentives perform less than any other incentive schemes and endogenous social norms in ensuring trust and fairness. These findings should make us reconsider the mantra of incentivization of social and public conventional policy.
Effect of Different Templates on the Synthesis of Mesoporous Sodalite
Authors: Shirani Lapari Shima , Ramli Zainab , Triwahyono Sugeng
Published: September 2015

Sodalite is a type of zeolite having ultramicropore size and high thermal stability with strong basic sites. However, sodalite has several drawbacks in the catalyst application due to its smallest pore size (2.8 Å) and low surface area. To overcome these disadvantages, microporous sodalite can be modified to have mesoporous structure but maintain its active sites suitable for catalyst applications. This study was focused on the synthesis of mesoporous sodalite using various organic templates as structure directing molecules. A hierarchical mesoporous sodalite has been synthesized hydrothermally at 150°C for crystallization by using several mesotemplate and fumed silica as a silica source. The synthesized samples were characterized using XRD, FTIR, BET surface area, and FESEM. XRD and FTIR showed that all templates being used in the synthesis produced sodalite phase. The sodalite synthesized using organosilane (trimethoxysilyl-propyldimethyloctadecyl ammonium chloride) and mixture of tetrapropyl ammonium hydroxide and cetyltrimethylammonium bromide with ratio of 1 : 1 showed mesoporosity as proven by higher BET surface area as compared to microporous sodalite with different pore structure as proven by pore distribution.
Iliac Crest Avulsion Fracture in a Young Sprinter
Authors: Casabianca L. , Rousseau R. , Loriaut P. , Massein A. , Mirouse G. , Gerometta A. , Khiami F.
Published: September 2015

Avulsion fracture of the iliac crest is an uncommon pathology. It usually occurs in teenagers during sport activities, more common in boys. We report a case of 16-year-old male competitive sprinter, who had an avulsion of a part of the iliac crest and the anterior-superior iliac spine during a competition. The traumatism occurred during the period of acceleration phase out of the blocks which corresponds to the maximum traction phase on the tendons. Then a total loss of function of the lower limb appears forcing him to stop the run. X-ray and CT scan confirmed the rare diagnosis of avulsion of the quasitotality of the iliac crest apophysis, corresponding to Salter 2 fracture. We performed an open reduction and internal fixation with two screws, allowing a return to sport after 3 months and his personal best record in the 100 meters at the 6th postoperative month.
Competition, Income Distribution, and the Middle Class: An Experimental Study
Authors: Kittel Bernhard , Paetzel Fabian , Traub Stefan
Published: September 2015

We study the effect of competition on income distribution by means of a two-stage experiment. Heterogeneous endowments are earned in a contest, followed by a surplus-sharing task. The experimental test confirms our initial hypothesis that the existence of a middle class is as effective as institutional hurdles in limiting the power of the less able in order to protect the more able players from being expropriated. Furthermore, majoritarian voting with a middle class involves fewer bargaining impasses than granting veto rights to the more able players and, therefore, is more efficient.
Effect ofLepidium meyeniiWalp. on Semen Parameters and Serum Hormone Levels in Healthy Adult Men: A Double-Blind, Randomized, Placebo-Controlled Pilot Study
Authors: Melnikovova Ingrid , Fait Tomas , Kolarova Michaela , Fernandez Eloy C. , Milella Luigi
Published: September 2015

Background/Aims.Products ofLepidium meyeniiWalp. (maca) are touted worldwide as an alimentary supplement to enhance fertility and restore hormonal balance. Enhancing properties of maca on semen parameters in animals were previously reported by various authors, but we present to the best of our knowledge the first double-blind, randomized, placebo-controlled pilot trial in men. The aim of this study was to evaluate the effects of maca on semen parameters and serum hormone levels in healthy adult men.Methods.A group of 20 volunteers aged 20–40 years was supplied by milled hypocotyl of maca or placebo (1.75 g/day) for 12 weeks. Negative controls of semen were compared to the samples after 6 and 12 weeks of maca administration; negative blood controls were compared to the samples after 12 weeks of treatment.Results.Sperm concentration and motility showed rising trends compared to placebo even though levels of hormones did not change significantly after 12 weeks of trial.Conclusion.Our results indicate that maca possesses fertility enhancing properties in men. As long as men prefer to use alimentary supplement to enhance fertility rather than prescribed medication or any medical intervention, it is worth continuing to assess its possible benefits.