bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic properties of the martensitic phase in Ni-Mn-In-Co metamagnetic shape memory alloys
Authors: Pérez-Landazábal J. I. , Recarte V. , Sánchez-Alarcos V. , Gómez-Polo C. , Cesari E.
Published: March 2013

The magnetic ground state of the martensitic phase in metamagnetic shape memory alloys seems to be dependent on the analyzed system. In Ni2Mn1+xZ1−x (Z = In, Sn, and Sb) alloys, ferromagnetic and antiferromagnetic interactions coexist in the martensitic state. Different mechanisms, i.e., reentrant spin glasses, superparamagnetism, or superspin glasses have been proposed to explain the martensitic magnetic behavior. In this letter, the magnetic properties of the martensitic phase in Ni-Mn-In-Co alloys have been determined. The martensitic phase shows the presence of superparamagnetic domains inside a paramagnetic matrix. On cooling, superspin glass features occur when interacting clusters are frozen below a critical temperature.
Gigahertz-frequency operation of a LaAlO3/SrTiO3-based nanotransistor
Authors: Irvin P. , Huang M. , Wong F. J. , Sanders T. D. , Suzuki Y. , Levy J.
Published: March 2013

Nanoscale control of the metal-insulator transition of the LaAlO3/SrTiO3 interface with a conductive-atomic force microscope (c-AFM) technique has enabled a variety of electrical and photonic device concepts. While previous devices have demonstrated sub-10 nm critical features, information processing applications also require high operating speeds. Here we show that a “sketched” nanoscale transistor (“SketchFET”) can operate at frequencies in excess of 2 GHz. The combination of high speed and high conductance with a small footprint make these devices and this platform attractive for sub-10 nm computing and storage architectures.
The infinite interface limit of multiple-region relaxed magnetohydrodynamics
Authors: Dennis G. R. , Hudson S. R. , Dewar R. L. , Hole M. J.
Published: March 2013

We show the stepped-pressure equilibria that are obtained from a generalization of Taylor relaxation known as multi-region, relaxed magnetohydrodynamics (MRXMHD) are also generalizations of ideal magnetohydrodynamics (ideal MHD). We show this by proving that as the number of plasma regions becomes infinite, MRXMHD reduces to ideal MHD. Numerical convergence studies illustrating this limit are presented.
Tunable graphene reflective cells for THz reflectarrays and generalized law of reflection
Authors: Carrasco Eduardo , Tamagnone Michele , Perruisseau-Carrier Julien
Published: March 2013

A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-beam reflectarrays, or similarly to implement the so-called generalized law of reflection. The change in the complex conductivity of graphene when biased by an electric field allows controlling the phase of the reflected field at each element of the array. Additionally, the slow wave propagation supported by graphene drastically reduces the dimensions of the cell, which allows smaller inter-element spacing hence better array performance. An elementary cell is optimized and its scattering parameters computed, demonstrating a dynamic phase range of 300° and good loss figure for realistic chemical potential variations. Finally, a circuit model is proposed and shown to very accurately predict the element response.
Ac susceptibility studies of a superconducting gallium nanocomposite: Crossover in the upper critical field line and activation barriers
Authors: Lee M. K. , Charnaya E. V. , Tien Cheng , Chang L. J. , Kumzerov Yu. A.
Published: March 2013

Ac magnetization measurements were carried out for a gallium nanocomposite consisted of a metal loaded porous glass with 3.5 nm pore size to study dynamics in the vortex system and H-T diagrams. Variations of ac magnetization with temperature and bias magnetic field were obtained at different frequencies and amplitudes of ac field. Double peaks in the imaginary part of ac susceptibility associated with doubly structured real parts with distinct dependences on the amplitude of ac field were observed. Activation barriers were evaluated from variations with frequency of the upper-temperature peak in χ″ at different bias fields. The field dependence of the activation barrier followed the power law with exponents equal to 0.12 and 1.0 below and above 20 kOe, respectively. A pronounced positive curvature was observed at low magnetic fields for the Hc2(T) line with the crossover to a common negative curvature near 20 kOe, also. Both the change of the exponent in the power law for activation barriers and the crossover to the negative curvature in the upper critical field line were suggested to occur due to transition in the vortex system from the geometry restricted to space between gallium particles into more homogeneous distribution with increasing field.
Enhanced pyroelectric properties of Cax(Sr0.5Ba0.5)1−xNb2O6 lead-free ceramics
Authors: Zhang Jing , Dong Xianlin , Cao Fei , Guo Shaobo , Wang Genshui
Published: March 2013

Cax(Sr0.5Ba0.5)1−xNb2O6 [CSBN(x), x = 0.00, 0.10, 0.15, and 0.20] lead-Free ceramics were prepared by a traditional solid-state reaction technique. Dielectric, ferroelectric, and pyroelectric properties of CSBN(x) lead-Free ceramics were systematically investigated. The pyroelectric properties of CSBN(x) have been enhanced remarkably due to Ca addition and reached the maximum values at x = 0.15, with pyroelectric coefficient of 3.61 × 10−8 C/cm2 K and pyroelectric figure of merit of Fi = 172 pm/V, Fv = 0.021 m2/C, and Fd = 11.5 μPa−1/2, which are superior to other lead-free ferroelectric ceramics. These results indicate the potential of CSBN(x) ceramics for infrared detector applications.
Effect of the magnetic order on the room-temperature band-gap of Mn-doped ZnO thin films
Authors: Wang X. L. , Luan C. Y. , Shao Q. , Pruna A. , Leung C. W. , Lortz R. , Zapien J. A. , Ruotolo A.
Published: March 2013

Exchange interaction between localized magnetic moments mediated by free charge carriers is responsible for a non-monotonic dependence of the low-temperature energy band-gap in dilute magnetic semiconductors. We found that in weakly doped Mn-ZnO films, increasing the exchange interaction by increasing the concentration of free charge carriers results in a red-shift of the near-band-edge emission peak at room temperature. An increase of Mn concentration widens the band gap, and a blue-shift prevails. Exchange interaction can be used to tune the room-temperature optical properties of the wide-band gap semiconductor ZnO.
Highly conformal magnesium oxide thin films by low-temperature chemical vapor deposition from Mg(H3BNMe2BH3)2 and water
Authors: Wang Wenjiao B. , Yang Yu , Yanguas-Gil Angel , Chang Noel N. , Girolami Gregory S. , Abelson John R.
Published: March 2013

Pure, dense, and stoichiometric MgO thin films have been deposited at temperatures as low as 225 °C by chemical vapor deposition using a recently reported magnesium precursor, magnesium N,N-dimethylaminodiboranate, which has the highest room-temperature vapor pressure among known Mg-containing compounds, with water as a co-reactant. The films are characterized by x-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and spectroscopic ellipsometry. Conformal coating on a trench with 35:1 aspect ratio is achieved at a film growth rate of 2 nm/min. The growth rate can be tuned between 2–20 nm/min according to the requirement of the structure to be coated.
Structural and electrical properties of BKT rich Bi0.5K0.5TiO3-K0.5Na0.5NbO3 system
Authors: Singh Amrita , Chatterjee Ratnamala
Published: March 2013

A new lead free (1−x) Bi0.5K0.5TiO3–(x) K0.5Na0.5NbO3 (BKT-KNN) system (0.0 ≤ x ≤ 0.15) with density of 94-97% is reported. Tetragonal structure of BKT-KNN is apparent for 0 ≤ x ≤ 0.06 with 1.02 ≤ (c/a) ≤ 1.012. Compositions with x ≥ 0.15 show orthorhombic structure (like KNN) and x = 0.08 & x = 0.10 are pseudocubic. Addition of KNN by a small amount (up to 4 mole %) is shown to improve piezoelectric properties, keeping the ferroelectric and dielectric values comparable to those of BKT. Optimized properties with d33 = 129 pC/N, kp = 29%, Pmax = 35 μC/cm2, Pr = 24 μC/cm2, ɛm = 4600, Tm = 370 °C and Td = 260 °C are observed for x = 0.03 sample. In the tetragonal range, a correlation between lattice distortion (c/a), piezoelectric coefficient (d33) and depolarization temperature Td is established. Decrease in c/a seems to result in easy poling by field and easy depoling by temperature, leading to an increase in d33 but a decrease in Td. A phase diagram for 1-xBKT-xKNN (0 ≤ x ≤ 0.10) is proposed. It is shown that addition of more than 6 mole % of KNN leads to the lowering of Td (where the structure becomes tetragonal to pseudocubic) considerably, resulting into a shift in tetragonal- pseudocubic phase boundary towards lower temperature.
Single crystalline ultrathin gold nanowires: Promising nanoscale interconnects
Authors: Roy Ahin , Pandey Tribhuwan , Ravishankar N. , Singh Abhishek K.
Published: March 2013

Using first principles based density functional calculation we study the mechanical, electronic and transport properties of single crystalline gold nanowires. While nanowires with the diameter less than 2 nm retain hexagonal cross-section, the larger diameter wires show a structural smoothening leading to circular cross-section. These structural changes significantly affect the mechanical properties of the wires, however, strength remains comparable to the bulk. The transport calculations reveal that the conductivity of these wires are in good agreement with experiments. The combination of good mechanical, electronic and transport properties make these wires promising as interconnects for nano devices.
Micromagnetic simulation of high-power spin-torque oscillator in half-metallic Heusler alloy spin valve nanopillar
Authors: Huang H. B. , Ma X. Q. , Liu Z. H. , Zhao C. P. , Chen L. Q.
Published: March 2013

We investigated the spin-torque oscillator in a half-metallic Heusler alloy Co2MnSi (CMS) spin-valve nanopillar using micromagnetic simulations. Although it is known that the out-of-plane precession (OPP) usually has a larger power output than the in-plane precession (IPP), only IPP mode was experimentally observed in CMS. Our simulations revealed the fundamental and second harmonic radio frequency (rf) oscillations of the IPP mode, consistent with the experimental measurements in CMS-based pillars. Our simulations predicted that the OPP mode can be obtained under the condition of an initially antiparallel state, a small external magnetic field, and a sufficiently large current density.
Accurate SHAPE-directed RNA secondary structure modeling, including pseudoknots
Authors: Hajdin Christine E. , Bellaousov Stanislav , Huggins Wayne , Leonard Christopher W. , Mathews David H. , Weeks Kevin M.
Published: March 2013

A pseudoknot forms in an RNA when nucleotides in a loop pair with a region outside the helices that close the loop. Pseudoknots occur relatively rarely in RNA but are highly overrepresented in functionally critical motifs in large catalytic RNAs, in riboswitches, and in regulatory elements of viruses. Pseudoknots are usually excluded from RNA structure prediction algorithms. When included, these pairings are difficult to model accurately, especially in large RNAs, because allowing this structure dramatically increases the number of possible incorrect folds and because it is difficult to search the fold space for an optimal structure. We have developed a concise secondary structure modeling approach that combines SHAPE (selective 2′-hydroxyl acylation analyzed by primer extension) experimental chemical probing information and a simple, but robust, energy model for the entropic cost of single pseudoknot formation. Structures are predicted with iterative refinement, using a dynamic programming algorithm. This melded experimental and thermodynamic energy function predicted the secondary structures and the pseudoknots for a set of 21 challenging RNAs of known structure ranging in size from 34 to 530 nt. On average, 93% of known base pairs were predicted, and all pseudoknots in well-folded RNAs were identified.
Formation of the –N(NO)N(NO)– polymer at high pressure and stabilization at ambient conditions
Authors: Xiao Hai , An Qi , Goddard William A. , Liu Wei-Guang , Zybin Sergey V.
Published: March 2013

A number of exotic structures have been formed through high-pressure chemistry, but applications have been hindered by difficulties in recovering the high-pressure phase to ambient conditions (i.e., one atmosphere and 300 K). Here we use dispersion-corrected density functional theory [PBE-
ulg
(Perdew-Burke-Ernzerhof flavor of DFT with the universal low gradient correction for long range London dispersion)] to predict that above 60 gigapascal (GPa) the most stable form of N
2
O (the laughing gas in its molecular form) is a one-dimensional polymer with an all-nitrogen backbone analogous to
cis
-polyacetylene in which alternate N are bonded (ionic covalent) to O. The analogous
trans
-polymer is only 0.03
∼
0.10 eV/molecular unit less stable. Upon relaxation to ambient conditions, both polymers relax below 14 GPa to the same stable nonplanar
trans
-polymer. The predicted phonon spectrum and dissociation kinetics validates the stability of this
trans
-poly-NNO at ambient conditions, which has potential applications as a type of conducting nonlinear optical polymer with all-nitrogen chains and as a high-energy oxidizer for rocket propulsion. This work illustrates
in silico
materials discovery particularly in the realm of extreme conditions (very high pressure or temperature).
Adaptive servo‐ventilation therapy improves cardiac sympathetic nerve activity in patients with heart failure
Authors: Koyama Takashi , Watanabe Hiroyuki , Tamura Yoshikazu , Oguma Yasunori , Kosaka Toshimitsu , Ito Hiroshi
Published: March 2013

Aims

This study investigated whether abnormal cardiac sympathetic nerve activity (SNA) is associated with the severity of central sleep apnoea (CSA) and whether adaptive servo‐ventilation (ASV) therapy can improve cardiac SNA in heart failure (HF) patients with predominant CSA.

Methods and results

Overnight polysomnography was conducted to diagnose CSA. Cardiac SNA was analysed by [123I]metaiodobenzylguanidine scintigraphy in 26 consecutive HF patients with predominant CSA. Of the 26 patients, 10 agreed to ASV therapy. Cardiac SNA was analysed 6 months after initiating ASV based on a non‐randomized protocol. The apnoea–hypopnoea index and central apnoea index were significantly correlated with the washout rate (WR) and a delayed heart to mediastinal (H/M) ratio, suggesting that SNA is associated with abnormal breathing patterns. The WR, H/M ratio, plasma BNP level, and LVEF were significantly improved (WR, 40.0 ± 11.6% vs. 34.6 ± 11.4%, P = 0.046; H/M ratio, 1.5 ± 0.1 vs.1.8 ± 0.3, P = 0.013; ln BNP, 5.4 ± 1.0 vs. 4.6 ± 1.2, P = 0.007; and LVEF, 43.8 ± 10.4% vs. 47.0 ± 10.6%, P < 0.001) in the ASV group patients, but not in the non‐ASV group patients. Multiple linear regression analyses showed that a decreased WR was strongly associated with an increased LVEF (coefficient = –0.454, P = 0.013).

Conclusions

Abnormal cardiac SNA could be significantly correlated with the severity of CSA in HF patients. ASV therapy might improve cardiac function in these patients by partially mediating cardiac SNA regulation.
Marinococcus

tarijensis sp. nov., a moderately halophilic bacterium isolated from a salt mine
Authors: Balderrama-Subieta Andrea , Guzmán Daniel , Minegishi Hiroaki , Echigo Akinobu , Shimane Yasuhiro , Hatada Yuji , Quillaguamán Jorge
Published: March 2013

A Gram-stain-positive, coccoid-shaped, halophilic bacterium, strain SR-1T, was isolated from a salt crystal obtained from a mine located in Tarija, Bolivia. The strain was investigated using a polyphasic approach. The optimum conditions for growth of strain SR-1T were reached at 5 % (w/v) NaCl, pH 7.6 and 37–40 °C. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The isoprenoid quinone was MK-7. The major cellular fatty acids of strain SR-1T were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The DNA G+C content of strain SR-1T was 48.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed a close relationship between strain SR-1T and

Marinococcus halophilus

JCM 2479T (99.7 % 16S rRNA gene sequence similarity),

Marinococcus halotolerans

KCTC 19045T (99.4 %) and

Marinococcus luteus

KCTC 13214T (99.8 %). However, strain SR-1T also showed low levels of DNA–DNA relatedness with these reference strains (47, 61 and 58 %, respectively). On the basis of phenotypic differences and DNA–DNA hybridization results, strain SR-1T is considered to represent a novel species of the genus

Marinococcus

, for which the name

Marinococcus

tarijensis sp. nov. is proposed. The type strain is SR-1T ( = LMG 26930T = CECT 8130T).
Phylogenetic placement of two previously described intranuclear bacteria from the ciliate Paramecium bursaria (Protozoa, Ciliophora): ‘Holospora acuminata’ and ‘Holospora curviuscula’
Authors: Rautian Maria S. , Wackerow-Kouzova Natalia D.
Published: March 2013

‘Holospora acuminata’ infects micronuclei of Paramecium bursaria (Protozoa, Ciliophora), whereas ‘Holospora curviuscula’ infects the macronucleus in other clones of the same host species. Because these micro-organisms have not been cultivated, their description has been based only on some morphological properties and host and nuclear specificities. One16S rRNA gene sequence of ‘H.
curviuscula’ is present in databases. The systematic position of the representative strain of ‘H.
curviuscula’, strain MC-3, was determined in this study. Moreover, for the first time, two strains of ‘H.
acuminata’, KBN10-1 and AC61-10, were investigated. Phylogenetic analysis indicated that all three strains belonged to the genus

Holospora

, family

Holosporaceae

, order

Rickettsiales

within the

Alphaproteobacteria

.
Paenibacillus

thermoaerophilus sp. nov., a moderately thermophilic bacterium isolated from compost
Authors: Ueda Junko , Yamamoto Shuichi , Kurosawa Norio
Published: March 2013

A rod-shaped, endospore-forming, Gram-reaction-positive bacterium, designated strain TC22-2bT, was isolated from compost in Tochigi, Japan. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain belonged to a cluster comprising species of the genus

Paenibacillus

and was most closely related to the type strain of

Paenibacillus elgii

(93.4 % similarity). The major cellular fatty acids were C16:0 (25.5 %), iso-C16:0 (23.6 %) and anteiso-C15:0 (21.5 %). The predominant menaquinone was MK-7. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The diamino acid found in the cell wall peptidoglycan was meso-diaminopimelic acid, and the DNA G+C content was 59.1 mol%. The results of physiological and biochemical tests enabled the phenotypic differentiation of strain TC22-2bT from the most closely related species with validly published names. Phylogenetic and phenotypic evidence reveals that strain TC22-2bT represents a novel species of the genus

Paenibacillus

, for which the name

Paenibacillus

thermoaerophilus sp. nov. is proposed. The type strain of the novel species is TC22-2bT ( = DSM 26310T  = JCM 18657T).
Oceanobacillus

polygoni sp. nov., a facultatively alkaliphile isolated from indigo fermentation fluid
Authors: Hirota Kikue , Hanaoka Yoshiko , Nodasaka Yoshinobu , Yumoto Isao
Published: March 2013

A facultatively alkaliphilic, lactic-acid-producing and halophilic strain, designated SA9T, was isolated from a fermented Polygonum indigo (Polygonum tinctorium Lour.) liquor sample prepared in a laboratory. The 16S rRNA gene sequence phylogeny suggested that strain SA9T was a member of the genus

Oceanobacillus

with the closest relative being

Oceanobacillus profundus

KCCM 42318T (99.3 % 16S rRNA gene sequence similarity). Cells of strain SA9T stained Gram-positive and were facultative anaerobic straight rods that were motile by peritrichous flagella. The strain grew between 5 and 48 °C (optimum, 35 °C) and at pH 7–12 (optimum, pH 9). The isoprenoid quinone detected was menaquinone-7 (MK-7) and the DNA G+C content was 40.6±0.9 mol%. The whole-cell fatty acid profile mainly consisted of iso-C15 : 0, anteiso-C15 : 0, C16 : 0 and anteiso-C17 : 0. DNA–DNA hybridization with

Oceanobacillus profundus

DSM 18246T revealed a DNA–DNA relatedness value of 23±2 %. On the basis of the differences in phenotypic and chemotaxonomic characteristics, and the results of phylogenetic analyses based on 16S rRNA gene sequences and DNA–DNA relatedness data from recognized species of the genus

Oceanobacillus

, strain SA9T merits classification as a representative of a novel species of the genus

Oceanobacillus

, for which the name

Oceanobacillus

polygoni sp. nov. is proposed. The type strain is SA9T ( = JCM 17252T = NCIMB 14684T). An emended description of the genus

Oceanobacillus

is also provided.
Polyphasic evidence supporting the reclassification of

Bradyrhizobium japonicum

group Ia strains as

Bradyrhizobium

diazoefficiens sp. nov.
Authors: Delamuta Jakeline Renata Marçon , Ribeiro Renan Augusto , Ormeño-Orrillo Ernesto , Melo Itamar Soares , Martínez-Romero Esperanza , Hungria Mariangela
Published: March 2013

Bradyrhizobium japonicum

was described from soybean root-nodule bacterial isolates. Since its description, several studies have revealed heterogeneities among rhizobia assigned to this species. Strains assigned to

B. japonicum

group Ia have been isolated in several countries, and many of them are outstanding soybean symbionts used in inoculants worldwide, but they have also been isolated from other legume hosts. Here, we summarize published studies that indicate that group Ia strains are different from the

B. japonicum

type strain USDA 6T and closely related strains, and present new morphophysiological, genotypic and genomic evidence to support their reclassification into a novel species, for which the name

Bradyrhizobium

diazoefficiens sp. nov. is proposed. The type strain of the novel species is the well-studied strain USDA 110T ( = IAM 13628T  = CCRC 13528T  = NRRL B-4361T  = NRRL B-4450T  = TAL 102T  = BCRC 13528T  = JCM 10833T  = TISTR 339T  = SEMIA 5032T  = 3I1B110T  = ACCC 15034T  = CCT 4249T  = NBRC 14792T  = R-12974T  = CNPSo 46T).
Bacillus

salsus sp. nov., a halophilic bacterium from a hypersaline lake
Authors: Amoozegar Mohammad Ali , Didari Maryam , Bagheri Maryam , Fazeli Seyed Abolhassan Shahzadeh , Schumann Peter , Spröer Cathrin , Sánchez-Porro Cristina , Ventosa Antonio
Published: March 2013

A Gram-staining-positive, endospore-forming, rod-shaped, strictly aerobic, slightly halophilic bacterium, designated strain A24T, was isolated from the hypersaline lake Aran-Bidgol in Iran. Cells of strain A24T were motile rods and produced oval endospores at a terminal position in swollen sporangia. Strain A24T was catalase and oxidase positive. Growth occurred with between 0.5 and 7.5 % (w/v) NaCl and the isolate grew optimally at 3 % (v/w) NaCl. The optimum temperature and pH for growth were 35 °C and pH 8.0, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain A24T belonged to the genus

Bacillus

within the phylum

Firmicutes

and showed the closest phylogenetic similarity with the species

Bacillus alkalitelluris

BA288T (97.2 %),

Bacillus herbersteinensis

D-1,5aT (96.0 %) and

Bacillus litoralis

SW-211T (95.6 %). The G+C content of the genomic DNA of this strain was 35.9 mol%. The polar lipid pattern of strain A24T consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and two unknown phospholipids. The major cellular fatty acids of strain A24T were anteiso-C15 : 0 and iso-C15 : 0. The respiratory quinones were MK-7 (94 %) and MK-6 (4 %). The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. All these features confirm the placement of isolate A24T within the genus

Bacillus

. DNA–DNA hybridization experiments revealed a relatedness of 8 % between strain A24T and

Bacillus alkalitelluris

IBRC-M 10596T, supporting its placement as a novel species. Phenotypic characteristics, phylogenetic analysis and DNA–DNA relatedness data suggest that this strain represents a novel species of the genus

Bacillus

, for which the name

Bacillus

salsus sp. nov. is proposed. The type strain is strain A24T ( = IBRC-M 10078 T = KCTC 13816T).
Traces of memory: Reacquisition of fear following forgetting is NMDAr-independent
Authors: Li Stella , Richardson Rick
Published: March 2013

Recent research shows that while initial learning is dependent on N-methyl-D-aspartate receptors (NMDArs), relearning can be NMDAr-independent. In the present study we examined whether this switch also occurs following forgetting. The developing animal exhibits much more rapid rates of forgetting than adults, so infant rats were used. It was found that infant rats required NMDArs to learn fear (Experiment 1), and that this memory was forgotten after 14 d (Experiment 2). Despite forgetting, relearning fear did not require NMDAr activation (Experiment 3), even if it occurred in adulthood (Experiment 5). Importantly, animals only showed NMDAr-independent reacquisition if they had received paired (white noise–shock) training during conditioning and not if they received unpaired presentations of the white noise and shock (Experiment 4). In addition, this transition following forgetting was not stimulus specific as learning about a novel stimulus (i.e., light, Experiment 6) was also NMDAr-independent. However, reacquisition to a novel stimulus was NMDAr-dependent if the original fear memory was retained at the time of retraining (Experiment 7). Taken together, these results demonstrate how fear memories acquired early in life can have a long-lasting impact on later learning, even when they have been apparently forgotten (i.e., they are not expressed in the animal’s overt behavior). Further, they support the idea that while memories may be forgotten, they are not gone.
Age-related cognitive impairments in mice with a conditional ablation of the neural cell adhesion molecule
Authors: Bisaz Reto , Boadas-Vaello Pere , Genoux David , Sandi Carmen
Published: March 2013

Most of the mechanisms involved in neural plasticity support cognition, and aging has a considerable effect on some of these processes. The neural cell adhesion molecule (NCAM) of the immunoglobulin superfamily plays a pivotal role in structural and functional plasticity and is required to modulate cognitive and emotional behaviors. However, whether aging is associated with NCAM alterations that might contribute to age-related cognitive decline is not currently known. In this study, we determined whether conditional NCAM-deficient mice display increased vulnerability to age-related cognitive and emotional alterations. We assessed the NCAM expression levels in the hippocampus and medial prefrontal cortex (mPFC) and characterized the performance of adult and aged conditional NCAM-deficient mice and their age-matched wild-type littermates in a delayed matching-to-place test in the Morris water maze and a delayed reinforced alternation test in the T-maze. Although aging in wild-type mice is associated with an isoform-specific reduction of NCAM expression levels in the hippocampus and mPFC, these mice exhibited only mild impairments in working/episodic-like memory performance. However, aged conditional NCAM-deficient mice displayed pronounced impairments in both the delayed matching-to-place and the delayed reinforced alternation tests. Importantly, the deficits of aged NCAM-deficient mice in these working/episodic-like memory tasks could not be attributed to increased anxiety-like behaviors or to differences in locomotor activity. Taken together, these data indicate that reduced NCAM expression in the forebrain might be a critical factor for the occurrence of cognitive impairments during aging.
Functional integrity of the retrosplenial cortex is essential for rapid consolidation and recall of fear memory
Authors: Katche Cynthia , Dorman Guido , Slipczuk Leandro , Cammarota Martín , Medina Jorge H.
Published: March 2013

Memory storage is a temporally graded process involving different phases and different structures in the mammalian brain. Cortical plasticity is essential to store stable memories, but little is known regarding its involvement in memory processing. Here we show that fear memory consolidation requires early post-training macromolecular synthesis in the anterior part of the retrosplenial cortex (aRSC), and that reversible pharmacological inactivation of this cortical region impairs recall of recent as well as of remote memories. These results challenge the generally accepted idea that neocortical areas are slow encoding systems that participate in the retrieval of remote memories only.
Which women are at an increased risk of a caesarean section or an instrumental vaginal birth in the UK: an exploration within the Millennium Cohort Study
Authors: Essex HN , Green J , Baston H , Pickett KE
Published: March 2013

Objective

To explore the maternal demographic factors associated with operative births (instrumental vaginal births or caesarean section), after adjustment for health, interpersonal, pregnancy, labour and infant covariates.

Design

Nationally representative cohort study.

Setting

Women giving birth in the UK, during the period 2000–2002.

Sample

A total of 18 239 mother–infant pairs.

Methods

Multinomial logistic regression models were estimated to explore the relationship between demographic characteristics and mode of birth, stratified by parity.

Main outcome measures

Self‐reported mode of birth, defined as unassisted vaginal birth, instrumental vaginal birth, emergency caesarean section and planned caesarean section.

Results

For primiparous women, operative births rose steeply with increasing maternal age. Women from lower occupational status households were at an increased risk of planned caesarean section. Mode of birth differed significantly by ethnicity. For multiparous women, a younger age at first birth was protective of a later caesarean section or instrumental vaginal birth at the cohort birth. Women with qualifications normally taken at the age 18 years were at an increased risk of planned caesarean section compared with women with degree‐level qualifications. Mode of birth differed significantly by ethnicity, and non‐UK born women were at an increased risk of emergency caesarean section.

Conclusions

The sociodemographic characteristics of UK women independently predict mode of birth. Further research is needed to establish to what extent sociodemographic differences in mode of birth are a reflection of the attitudes and behaviours of women, or health professionals, and are therefore amenable to change.
Hutchinson–Gilford progeria syndrome through the lens of transcription
Authors: Prokocimer Miron , Barkan Rachel , Gruenbaum Yosef
Published: March 2013

Lamins are nuclear intermediate filaments. In addition to their structural roles, they are implicated in basic nuclear functions such as chromatin organization, DNA replication, transcription, DNA repair, and cell‐cycle progression. Mutations in human LMNA gene cause several diseases termed laminopathies. One of the laminopathic diseases is Hutchinson–Gilford progeria syndrome (HGPS), which is caused by a spontaneous mutation and characterized by premature aging. HGPS phenotypes share certain similarities with several apparently comparable medical conditions, such as aging and atherosclerosis, with the conspicuous absence of neuronal degeneration and cancer rarity during the short lifespan of the patients. Cell lines from HGPS patients are characterized by multiple nuclear defects, which include abnormal morphology, altered histone modification patterns, and increased DNA damage. These cell lines provide insight into the molecular pathways including senescence that require lamins A and B1. Here, we review recent data on HGPS phenotypes through the lens of transcriptional deregulation caused by lack of functional lamin A, progerin accumulation, and lamin B1 silencing.
Enhancing tourist opportunities to view spotted‐necked otters (Lutra maculicollis) at Rubondo Island National Park: can the apriori location of latrines simplify identifying best viewing areas?
Authors: Amulike Bridget , Stevens Sadie S. , Serfass Thomas L.
Published: March 2013

We observed spotted‐necked otters (Lutra maculicollis) along a 5.17‐km section of shoreline at Rubondo Island National Park, Tanzania, during May 2008 and February, June–August 2009 to determine whether their activity areas were associated with latrine site (places along the shoreline where spotted‐necked otters scent mark by depositing scats and urine) as part of an assessment to determine how tourists or researchers can best view the species. For this assessment, we compared the distance of spotted‐necked otters sightings associated with the shoreline (n = 207) with the distance between an equal number of geographical information system (GIS)‐generated random points to the nearest latrine for each of the respective points. The mean distances for locations of spotted‐necked otter sightings to the nearest latrine differed from the mean distance of random points to latrines [171.9 m (SE = 11.30) and 66.1 m (SE = 8.16), respectively; t = −9.23, df = 412, P < 0.001]. Sightings also were much (2.6 times) closer to latrines that occurred in groups than those that were isolated (single). Establishing viewing sites at or near latrines (particularly those occurring in clusters) would thus seem an effective way to maximize opportunities to see spotted‐necked otters.
Uncemented Primary Total Hip Arthroplasty, Presentation of Pain, and Expression of Osteonectin
Authors: Beraudi Alina , Montesi Monica , Traina Francesco , Falcioni Stefano , Stea Susanna , Toni Aldo
Published: March 2013

Osteonectin (ON) is an important matrix glycoprotein highly expressed in bone. In several in vitro and animal model studies, ON was used as indicator of the state of osseointegration of implanted devices. There are, however, no studies on ON expression in the synovial fluid of patients with total hip joint replacement (THJR). The purpose of our study was to determine the ON concentration in synovial fluid from three groups of patients: primary uncemented THJR with hip pain (“pain” group; n = 15) and without pain (“no‐pain” group; n = 12), and patients with osteoarthitis scheduled to receive a primary THJR (control group; n = 5). For the prosthesized groups, the statistical nature of the correlation between ON concentration and patient age, in situ life of the THJR, presence of periprosthetic osteolysis, and presence of debris in the synovial fluid was individually investigated. ON concentration was determined using enzyme‐linked immunosorbent assay, the presence of periprosthetic osteolysis was established using X‐radiography and Engh's criteria, and the presence of debris was determined using digestion and EDX spectroscopy. ON concentration was significantly lower in the “pain” group compared with the “no‐pain” one (median values 19.0 and 53.2 ng/mL, respectively). ON concentration in the control group (median value: 16.9 ng/mL) was comparable with that reported in the literature. In the prosthesized groups, ON concentration was not correlated with patient age, in situ life of the prosthesis, presence of periprosthetic osteolysis, or presence of debris in the synovial fluid. Our results suggest that cases of unexplained pain in THJR patients could be treated by paying special attention to the osseointegration status of the implant by using ON concentration as an early indicator of this status.
The Cuban program for predictive testing of SCA2: 11 years and 768 individuals to learn from
Authors: Cruz‐Mariño T , Velázquez‐Pérez L , González‐Zaldivar Y , Aguilera‐Rodríguez R , Velázquez‐Santos M , Vázquez‐Mojena Y , Estupiñán‐Rodríguez A , Laffita‐Mesa JM , Reynaldo‐Armiñán R , Almaguer‐Mederos LE , Paneque M
Published: March 2013

Having reported the world's highest prevalence of spinocerebellar ataxia type 2 (SCA2), health professionals in Cuba developed a program for the predictive testing of this condition. Between February 2001 and December 2011, a total of 1050 individuals requested their inclusion in the presymptomatic testing (PST) program. Their medical records were retrospectively analyzed in the present descriptive study. A total of 768 participants completed the protocol, 204 withdrew and 78 were excluded. The PST uptake was 24.91%. Females predominated and 70.96% had negative test results. Their main motivations were risk assessment in their descendants, physical and psychological preparation to cope with the disease and planning for the future. The profile of Cuban participants in the predictive testing program is similar to the one reported for other programs all over the world, nevertheless the genetic counseling practice at the community level is a distinctive aspect, which is valuable in providing at‐risk individuals with wide and proper knowledge before their testing inclusion request. The SCA2 predictive testing program has high uptake rates and is renowned in our population. Future research is needed to assess the long‐term psychological impact in the participants, their partners and relatives.
Cash flow vs. collateral‐based credit
Authors: Cassano Francesca , Jõeveer Karin , Svejnar Jan
Published: March 2013

We study factors affecting micro, small and medium‐sized enterprises (MSMEs) receiving loans and the effect of these loans on MSMEs performance. We study two types of loans – a new type based on cash flows and a traditional‐style loan based on collateral. We use unique surveys of MSMEs from Bulgaria, Georgia, Russia and Ukraine. We find that MSMEs receiving a cash flow or collateral loan in the past are more likely to receive the same type of loan (and larger sized) in the future and that cash flow loans may be the preferred form of credit. Both types of loans are related positively to most performance indicators, enabling the MSMEs for instance to be more profitable and expand production. The cash flow loans also appear to be particularly attractive credit delivery schemes for micro and small enterprises. Finally, the effects of the smallest loans are often negative, suggesting that the minimum loan size is an important policy issue.
Hydrogeochemical dynamics affecting steam‐heated pools at El Chichón Crater (Chiapas – Mexico)
Authors: Cuoco E. , De Francesco S. , Tedesco D.
Published: March 2013

El Chichón is an active volcano located in the north‐westernChiapas, southernMexico. The crater hosts a lake, a spring, named Soap Pool, emerging from the underlying volcanic aquifer and several mud pools/hot springs on the internal flanks of the crater which strongly interact with the current fumarolic system (steam‐heated pools). Some of these pools, the crater lake and a cold spring emerging from the 1982 pumice deposits, have been sampled and analysed. Water–volcanic gas interactions determine the heating (43–99°C) and acidification (pH2–4) of the springs, mainly by H2S oxidation. Significantly, in the study area, a significant NH3partial pressure has been also detected. Such a geochemically aggressive environment enhances alteration of the rockin situand strongly increases the mineralization of the waters (and therefore their electrical conductivity). Two different mineralization systems were detected for the crater waters: the soap pool‐lake (Na+/Cl− = 0.4, Na/Mg>10) and the crater mud pools (Na+/Cl− > 10, Na/Mg < 4). A deep boiling, Na+‐K+‐Cl−‐rich water reservoir generally influences the Soap Pool‐lake, while the mud pool is mainly dominated by water‐gas–rock interactions. In the latter case, conductivity of sampled water is directly proportional to the presence of reactive gases in solution. Therefore, chemical evolution proceeds through neutralization due to both rock alteration and bacterial oxidation of ammonium to nitrate. The chemical compositions show that El Chichón aqueous fluids, within the crater, interact with gases fed by a geothermal reservoir, without clear additions of deep magmatic fluids. This new geochemical dataset, together with previously published data, can be used as a base line with which to follow‐up the activity of this deadly volcano.
Thermochemistry of Barium Hollandites
Authors: Costa Gustavo C. C. , Xu Hongwu , Navrotsky Alexandra
Published: March 2013

Barium hollandites, a family of framework titanates that can potentially be used for the immobilization of short‐lived fission products (especially 137Cs) in radioactive wastes, have been investigated by high‐temperature oxide melt solution calorimetry using 2PbO·B2O3 solvent at 702°C. The enthalpies of formation from constituent oxides show increasing energetic stability of the hollandite phase as Ti4+ is substituted by Mg2+, Al3+, and Fe3+, in that order. In general, the thermodynamic stability increases with decreasing average cation radius in the β sites, and when the tolerance factor approaches one. The Al‐ and Fe‐hollandites are more stable than phase assemblages containing BaTiO3 perovskite and Al/Fe/Ti oxides, whereas Mg‐hollandite is less stable than the corresponding assemblage of BaTiO3 perovskite, MgTiO3 ilmenite, and TiO2. This instability makes Mg‐hollandite a less suitable host for fission products. Hollandite phase formation during metal citrate combustion synthesis depends more on thermodynamic stability and phase chemistry than on the annealing temperature.
Piezoelectric Properties of Lead‐free Piezoelectric Ceramics and Their Energy Harvester Characteristics
Authors: Seo In‐Tae , Choi Chang‐Hoi , Song Daniel , Jang Min‐Soo , Kim Bo‐Yun , Nahm Sahn , Kim Young‐Sik , Sung Tae‐Hyun , Song Hyun‐Cheol
Published: March 2013

The energy convergence efficiency (η) and dimensionless figure of merit (DFOM) of CuO‐added (Na0.5K0.5)NbO3 (CNKN) ceramics are larger than those of NKN ceramics because of their large Qm values and small dielectric losses. Moreover, the η and DFOM values of CNKN ceramics are comparable to those of P‐5C ceramics, which exhibit the highest η and DFOM. Furthermore, the CNKN harvester exhibits a high power density of 12 mW/cm3 at 93 Hz with a load resistance of 250 kΩ; this is similar to the PZT‐based energy harvester, indicating that the CNKN ceramic is a good candidate material for energy harvesters.
Degradation Analysis of the SnO2 and ZnO‐Based Varistors Using Electrostatic Force Microscopy
Authors: Ramírez M. A. , Tararam R. , Simões A.Z. , Ries A. , Longo E. , Varela J. A.
Published: March 2013

The degradation phenomena of ZnO and SnO2‐based varistors were investigated for two different degradation methods: DC voltage at increased temperature and degradation with 8/20 μs pulsed currents (lightning type). Electrostatic force microscopy (EFM) was used to analyze the surface charge accumulated at grain‐boundary regions before and after degradation. Before the degradation process, 85% of the barriers are active in the SnO2 system, while the ZnO system presents only 30% effective barriers. Both systems showed changes in the electrical behavior when degraded with pulses. In the case of the ZnO system, the behavior after pulse degradation was essentially ohmic due to the destruction of barriers (about 99% of the interfaces are conductive). After the degradation with 8/20 μs pulsed currents, the SnO2 system still presents nonohmic behavior with a significant decrease in the quantity of effective barriers (from 85% to 5%). However, when the degradation is accomplished with continuous current, the SnO2 system exhibits minimum variation, while the ZnO system degrades from 30% to 5%. This result indicates the existence of metastable defects of low concentration and/or low diffusion in the SnO2 system. High energy is necessary to degrade the barriers due to defect annihilation in the SnO2 system.
Escherichia coli Concentrations in Urban Watersheds Exhibit Diurnal Sag: Implications for Water‐Quality Monitoring and Assessment
Authors: Desai Anuradha M. , Rifai Hanadi S.
Published: March 2013

The variability of indicator bacteria over a fine resolution time scale on the order of minutes has yet to be fully understood. In this study, we collected more than 700 Escherichia coli samples at a 10‐ and 30‐min resolution in an urban watershed in Houston. A Bacteria Diurnal Sag (BDS) marked with daytime exponential decay followed by an exponential nighttime regeneration was observed. This pattern was observed during all sampled events but varied depending on other variables. The concentrations during a 24‐h period varied 1 to 5 orders of magnitude and the fecal load was at least 10 times lower than what would be obtained using a single morning E. coli measurement, the typical sampling scheme in most monitoring programs. Decay rates, ranging from 3.67 to 24.7/day, decreased E. coli concentrations to below the water‐quality standards from 14:00 to 18:00 h and were strongly influenced by water temperatures and solar radiation intensities. Rapid regeneration occurred on the order of 9.41 to 64.1/day allowing E. coli concentrations to return to their pre‐decay levels. The data indicated that four to six samples taken between 06:00 and 18:00 h may be sufficient to define the BDS depending on stream conditions, and that a threshold concentration of approximately 100 MPN/dl (most probable number in a deciliter) existed for the studied urban watershed. These findings have significant implications for water‐quality monitoring, regulation, and compliance.
Historical biogeography and ecological opportunity in the adaptive radiation of native Hawaiian leafhoppers (Cicadellidae: Nesophrosyne)
Authors: Bennett Gordon M. , O'Grady Patrick M.
Published: March 2013

Aim

Our aims were to infer the roles of ecology and geology in the adaptive radiation, historical biogeography, and diversification dynamics of the native Hawaiian leafhoppers (Hemiptera: Cicadellidae: Nesophrosyne).

Location

The Hawaiian Archipelago.

Methods

A six gene molecular data set for 191 Nesophrosyne species was used to reconstruct relationships in absolute time with relaxed Bayesian methods. Dated phylogenetic hypotheses were used to reconstruct historical biogeography and host plant associations. Phylogenetic clustering methods were implemented to examine the structuring of Nesophrosyne species according to island. Lineage diversification dynamics were inferred using the γ‐statistic and birth–death likelihood methods.

Results

Nesophrosyne split from a common ancestor with its sister genus 4.5 million years ago (Ma), with a basal divergence in Hawaii 3.2 Ma. Historical biogeographical reconstructions reveal a Kauai origin for the genus and complex island colonization patterns. Ancestral host plant associations reconstruct Urticaceae and Rubiaceae at the root, with host transitions resulting in host‐specific clades. Only species endemic to Kauai are significantly clustered with respect to the whole phylogeny; however, species show significant terminal level clustering for the four main high islands. Diversification rates in Nesophrosyne show an initial burst in net speciation rate with a subsequent decline.

Main conclusions

Nesophrosyne colonized the Hawaiian Islands after the formation of Kauai. Host plant arrival times and insect–insect competition may have been important in shaping diversification patterns. The plant families Urticaceae and Rubiaceae played critical roles in the early diversification of Nesophrosyne. Island geography imposed significant barriers to gene flow, leading to extensive allopatric speciation and intra‐island diversification. A high initial net speciation rate was associated with host plant transitions, and the formation and establishment of Nesophrosyne on multi‐volcano islands (e.g. Oahu and Maui Nui). Net diversification rates exhibit a diversity‐dependent decline, corresponding to the end phase of island formation.