bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraosseous Sacral Paraganglioma with Extradural Extension
Authors: Falavigna Asdrubal , Righesso Orlando , Teles Alisson Roberto , Conzatti Lucas Piccoli , Rizkalla Elisa Braun
Published: May 2015

Introduction

Paragangliomas are tumors that arise from the paraganglion system, which is a component of the neuroendocrine system. Approximately, 10% are located in the extra-adrenal paraganglion system. Paragangliomas of the spine, however, are rare. They usually present as an intradural tumor in the cauda equina. There are only three reports of primary intraosseous paragangliomas of the sacrum. Patient and Methods: A 69-year-old man presented with low back pain and urinary incontinence. Imaging revealed a large intraosseous mass at S2, S3, and S4. Surgical resection was accomplished through a posterior midline incision exposing the spine from L5 to the coccyx. The tumor was located in the extradural space. It was friable, grayish, and bleeding. Total tumor removal was performed, with normal bone margins. Follow-up at 2 years showed complete resolution of the preoperative symptoms and no evidence of local recurrence.

Results

Extra-adrenal paragangliomas have been found in locations where paraganglia are not normally located, such as the stomach, duodenum, uterus, and lungs. In the central nervous system, a few cases in the cerebellopontine angle and cerebellum have been described. A spinal location is also rare; tumors have been found in the intradural, extramedullary compartment, predominantly in the lumbar region and, rarely, in the cervical or thoracic regions. Only three cases of paraganglioma originating primarily within sacral bone have been reported. In 1998, Coles reported the first case of a primary intraosseous tumor, located at S3. This was followed by a report from Sundgern in 1999 of another case located at the S1 vertebral body. Recently, in 2007, Laufer reported the third case of primary sacral paraganglioma, located at the S1 vertebral body.

Conclusion

Although rare, the possibility of paraganglioma should be included in the differential diagnosis of sacral tumors. The majority of the spinal paragangliomas are benign, slowly growing tumors with low proliferative activity. Despite these characteristics, local recurrence has been reported in cases of both macroscopically total and subtotal resection. Postoperative radiation therapy for patients with incomplete excision may not prevent recurrence, so gross tumor removal should be the goal of surgery.
Sacrococcygeal Teratoma in Children
Authors: Falavigna Asdrubal , Gandara Carlos , Radaelli Lucas , Merlin Luiz Henrique , Wurzius Francine , Bassanesi Francisco
Published: May 2015

Introduction

Germ cell tumors originate in the primary stem cell located either inside or outside the gonadal system. Teratomas are the major group, with the sacrococcygeal location being the most common extragonadal site, independent of their being benign or malignant. We describe five cases of sacrococcygeal teratoma and emphasize aspects of diagnosis, surgical techniques, and complementary approaches.

Patients and Methods

A total of five cases of sacrococcygeal teratoma were reported and a literature review was performed using an online database, Pubmed.gov. The authors emphasize aspects of diagnosis, classification, prognosis, and the therapeutic options.

Results

The five cases were females and the age range from 38 weeks intrauterine (ultrasonography diagnosis) to 1.5 years. The clinical presentation usually was a sacral mass or fecal constipation. The Altman classification was type 1 in three cases and type 4 in two cases. The serum levels of α-fetoprotein was normal in three cases. Preoperative high serum α-fetoprotein levels returned to normal levels 10 days after surgery. The radical surgical resection of the tumor and the coccyx was done in all cases through a posterior sacral approach and midline incision. The surgery did not compromise the neurological function. No tumor recurrence was seen in by radiologic and α-fetoprotein examinations after a medium follow-up of 15.3 years.

Conclusion

The sacrococcygeal region is the most frequent site of teratomas in children. Complete tumor resection and removal of the coccyx are the main objective in curative treatment of the teratoma. Diagnosis and treatment as early as possible is essential to prevent it from becoming malignant.
Restoring the Spino-Pelvic Parameters Correlates with Better Outcome in Adult Deformity Surgical Correction?
Authors: Barbanti Brodano Giovanni , Babbi Lisa , Colangeli Simone , Girolami Marco , Gasbarrini Alessandro
Published: May 2015

Introduction

The surgical approach to adult deformities is challenging both in terms of surgical planning and of amount of complications. Current literature shows potential benefits in surgical correction of adult deformities; recovery of both frontal and sagittal balance seems to be the key for satisfactory outcomes.

Patients and Methods

In this retrospective study, from an initial pattern of 30 patients, 12 selected patients were considered. All patients, average age 57 years, underwent adult scoliosis surgical correction. We evaluated the clinical outcomes in correlation with restoring of the sagittal balance and the rate of complications and mechanical failure. Previous surgery was not an exclusion criteria. Average follow-up was 8.2 months (range, 3–20 months). Clinical evaluation was performed by using Visual Analog Score test, Oswestry Disability Index, and Quality of Life test. Radiological measures were performed by software Surgimap Spine.

Results

In 10 cases (83% of patients), we observed agreement between clinical and radiological outcomes (we focused in particular on sagittal balance). To a satisfactory recovery of sagittal balance, in eight cases we found improvement at clinical tests while in two cases to a poor balance correction, the patients' quality of life did not improve. In only two cases (16% of patients), we found disagreement between the two parameters indicated (sagittal balance and quality of life). In our series, five patients had mechanical failures: four of them did not improve their sagittal balance at postoperative X-ray.

Conclusion

The purpose of this study was to validate the hypothesis that good clinical results in adult deformities correction are better achieved when restoration of sagittal balance is obtained. The large agreement among quality of life evaluation and recovery of sagittal balance we observed in this preliminary series of selected patients seems to hold it up. Moreover, the respect of physiological pelvic parameters seems to reduce the number of adverse events in terms of mechanical failures and consequently the number of reoperations; its indeed necessary to underline how 100% of patients whose sagittal balance did not improve with surgery had mechanical failure of instrumentation. Only one patient with acceptable sagittal parameters needed reoperation because of breaking of the rods.
Microscopically Assisted versus Standard Laparotomy L5–S1 Circumferential Fusion
Authors: Buric Josip , Bombardieri Domenico
Published: May 2015

Introduction

Microscopically assisted retroperitoneal laparotomy is a minimally invasive modification of a standard approach for anterior lumbar interbody fusion (ALIF). In this study, we compare the peri- and immediate postoperative results of standard versus microscopically assisted L5–S1 interbody fusion.

Patients and Methods

A total of 20 patients with low back pain because of the degenerative disc disease and/or spondylolisthesis were included in the study. Overall, 10 patients were submitted to a single-stage microscopically assisted left-retroperitoneal interbody fusion and 10 patients were submitted to a single-stage standard left-retroperitoneal interbody fusion. All patients were instrumented posteriorly with screw and rod system. Data were collected for vascular and visceral injuries, blood loss, operating time, walk-out-of-bed time, peristalsis recovery, and initial 48 hours pain levels.

Results

Significant differences were found for vascular lesion and blood loss between the two groups with the standard laparotomy group being on the worse side. Furthermore, patients subjected to a microscopically assisted approach showed a more rapid recovery of intestinal peristalsis, a reduced walk-out-of-bed time, and a lower intensity of perceived pain in the first 48 hours after the surgery.

Conclusion

The results of this study indicate the minimally invasive approach for ALIF as an equally efficient but much safer approach as compared with the standard laparotomy approach. Reduction of complications and a shorter in-hospital stay contribute on lowering the costs of the treatment making it not only clinically, but also economically more suitable surgical choice.
Clinical and Surgical Predictors of Specific Complications following Surgery for the Treatment of Degenerative Cervical Myelopathy: Results from the Multicenter, Prospective AOSpine International Study on 479 Patients
Authors: Fehlings Michael , Tetreault Lindsay , Kopjar Branko , Arnold Paul , Defino Helton , Kale Shashank , Barbagallo Giuseppe , Zileili Mehmet , Tan Gamiel , Yukawa Yasutsugu , Moraes Osmar , Scerrati Massimo , Tanaka Masato , Toyone Tomoaki , Bolger Ciaran , Cote Pierre
Published: May 2015

Introduction

This study aimed to identify important clinical and surgical predictors of perioperative complications in patients with CSM. This knowledge will help clinicians recognize their high-risk patients and allow them to institute appropriate prevention plans.

Material and Methods

This study aimed to identify important clinical and surgical predictors of perioperative complications in patients with CSM. This knowledge will help clinicians recognize their high-risk patients and allow them to institute appropriate prevention plans.

Results

A total of 80 patients experienced 92 perioperative complications (16.7%). Univariately, the major clinical risk factors were OPLL ( p = 0.022), the number of comorbidities ( p = 0.020), diabetes ( p = 0.004), and coexisting gastrointestinal disorders ( p = 0.045). Patients undergoing a two-stage surgery and those with a longer operative duration were also at a greater risk of perioperative complications. A final model consisted of diabetes (OR = 2.35, p = 0.039), age (OR = 1.02, 0.25), operative duration (OR = 1.003, p = 0.17), two-stage surgery (OR = 20.37, p = 0.012), OPLL (OR = 1.82, p = 0.064), gastrointestinal comorbidities (OR = 2.53, p = 0.020), and BMI (OR = 1.06, p = 0.10).

Conclusion

Patients are at a higher risk of perioperative complications if they are older; have OPLL, a higher BMI, diabetes or gastrointestinal disorders; and if they undergo a two-stage surgery and a long operation.
Management of Combined Atlas–Axis Fractures with Anterior Transarticular Fixation in Elderly Patients
Authors: Kocis Jan
Published: May 2015

Introduction

Posterior techniques of treatment in atlas–axis combined injury are reported less prone to failure of osteosynthesis. At the same time, however, more frequent occurrence of complications is presented, mainly consisting of higher blood loss, reduced wound healing, chronic pain, and possibility of injury of a. vertebralis. In addition, prone position is not suitable for elderly patients from the anesthesiologist perspective. On the contrary, the frequent failure of anterior osteosynthesis of dens axis because of osteoporosis calls for finding alternative solutions.

Patients and Methods

Between 2009 and 2013, 10 consecutive patients with combined C1/C2 fractures underwent triple anterior screw fixation in our hospital. The group consisted of 10 women. The age ranged between 67 and 90 years. The patients follow-up was 1 year.

Results

The operation was performed without complications in all patients. Early postoperative failure of screws in C1 was observed in one patient. Reoperation was required. The bone was healed in fracture of dens axis in eight patients according to CT examination. Pseudoarthrosis without clinical sequelae was found in two patients. None of the patients had neurological disorder and we had no patient deaths during the period under review.

Conclusion

This method allows simple and safe treatment of combined atlas–axis fractures.
A periodic energy decomposition analysis method for the investigation of chemical bonding in extended systems
Authors: Raupach Marc , Tonner Ralf
Published: May 2015

The development and first applications of a new periodic energy decomposition analysis (pEDA) scheme for extended systems based on the Kohn-Sham approach to density functional theory are described. The pEDA decomposes the bonding energy between two fragments (e.g., the adsorption energy of a molecule on a surface) into several well-defined terms: preparation, electrostatic, Pauli repulsion, and orbital relaxation energies. This is complemented by consideration of dispersion interactions via a pairwise scheme. One major extension toward a previous implementation [Philipsen and Baerends, J. Phys. Chem. B 110, 12470 (2006)] lies in the separate discussion of electrostatic and Pauli and the addition of a dispersion term. The pEDA presented here for an implementation based on atomic orbitals can handle restricted and unrestricted fragments for 0D to 3D systems considering periodic boundary conditions with and without the determination of fragment occupations. For the latter case, reciprocal space sampling is enabled. The new method gives comparable results to established schemes for molecular systems and shows good convergence with respect to the basis set (TZ2P), the integration accuracy, and k-space sampling. Four typical bonding scenarios for surface-adsorbate complexes were chosen to highlight the performance of the method representing insulating (CO on MgO(001)), metallic (H2 on M(001), M = Pd, Cu), and semiconducting (CO and C2H2 on Si(001)) substrates. These examples cover diverse substrates as well as bonding scenarios ranging from weakly interacting to covalent (shared electron and donor acceptor) bonding. The results presented lend confidence that the pEDA will be a powerful tool for the analysis of surface-adsorbate bonding in the future, enabling the transfer of concepts like ionic and covalent bonding, donor-acceptor interaction, steric repulsion, and others to extended systems.
Portable microwave frequency dissemination in free space and implications on ground-to-satellite synchronization
Authors: Miao J. , Wang B. , Bai Y. , Yuan Y. B. , Gao C. , Wang L. J.
Published: May 2015

Frequency dissemination and synchronization in free space play an important role in global navigation satellite system, radio astronomy, and synthetic aperture radar. In this paper, we demonstrated a portable radio frequency dissemination scheme via free space using microwave antennas. The setup has a good environment adaptability and high dissemination stability. The frequency signal was disseminated at different distances ranging from 10 to 640 m with a fixed 10 Hz locking bandwidth, and the scaling law of dissemination stability on distance and averaging time was discussed. The preliminary extrapolation shows that the dissemination stability may reach 1 × 10−12/s in ground-to-satellite synchronization, which far exceeds all present methods, and is worthy for further study.
Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy
Authors: Nenov Artur , Giussani Angelo , Segarra-Martí Javier , Jaiswal Vishal K. , Rivalta Ivan , Cerullo Giulio , Mukamel Shaul , Garavelli Marco
Published: May 2015

Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide conformational dependent fingerprints in dimeric systems, the performances of the selected reduced level of calculations have been tested in the construction of 2D electronic spectra for the in vacuo adenine monomer and the unstacked adenine homodimer, thereby exciting the Lb/La transitions with the pump pulse pair and probing in the Vis to near ultraviolet spectral window.
Memristive operation mode of a site-controlled quantum dot floating gate transistor
Authors: Maier P. , Hartmann F. , Mauder T. , Emmerling M. , Schneider C. , Kamp M. , Höfling S. , Worschech L.
Published: May 2015

We have realized a floating gate transistor based on a GaAs/AlGaAs heterostructure with site-controlled InAs quantum dots. By short-circuiting the source contact with the lateral gates and performing closed voltage sweep cycles, we observe a memristive operation mode with pinched hysteresis loops and two clearly distinguishable conductive states. The conductance depends on the quantum dot charge which can be altered in a controllable manner by the voltage value and time interval spent in the charging region. The quantum dot memristor has the potential to realize artificial synapses in a state-of-the-art opto-electronic semiconductor platform by charge localization and Coulomb coupling.
Generating static perfect-fluid solutions of Einstein’s equations
Authors: Quevedo Hernando , Toktarbay Saken
Published: May 2015

We present a method for generating exact interior solutions of Einstein’s equations in the case of static and axially symmetric perfect-fluid spacetimes. The method is based upon a transformation that involves the metric functions as well as the density and pressure of the seed solution. In the limiting vacuum case, it reduces to the Zipoy-Voorhees transformation that can be used to generate metrics with multipole moments. All the metric functions of the new solution can be calculated explicitly from the seed solution in a simple manner. The physical properties of the resulting new solutions are shown to be completely different from those of the seed solution.
A fast and reliable readout method for quantitative analysis of surface-enhanced Raman scattering nanoprobes on chip surface
Authors: Chang Hyejin , Kang Homan , Jeong Sinyoung , Ko Eunbyeol , Lee Yoon-Sik , Lee Ho-Young , Jeong Dae Hong
Published: May 2015

Surface-enhanced Raman scattering techniques have been widely used for bioanalysis due to its high sensitivity and multiplex capacity. However, the point-scanning method using a micro-Raman system, which is the most common method in the literature, has a disadvantage of extremely long measurement time for on-chip immunoassay adopting a large chip area of approximately 1-mm scale and confocal beam point of ca. 1-μm size. Alternative methods such as sampled spot scan with high confocality and large-area scan method with enlarged field of view and low confocality have been utilized in order to minimize the measurement time practically. In this study, we analyzed the two methods in respect of signal-to-noise ratio and sampling-led signal fluctuations to obtain insights into a fast and reliable readout strategy. On this basis, we proposed a methodology for fast and reliable quantitative measurement of the whole chip area. The proposed method adopted a raster scan covering a full area of 100 μm × 100 μm region as a proof-of-concept experiment while accumulating signals in the CCD detector for single spectrum per frame. One single scan with 10 s over 100 μm × 100 μm area yielded much higher sensitivity compared to sampled spot scanning measurements and no signal fluctuations attributed to sampled spot scan. This readout method is able to serve as one of key technologies that will bring quantitative multiplexed detection and analysis into practice.
Resurgence and holomorphy: From weak to strong coupling
Authors: Cherman Aleksey , Koroteev Peter , Ünsal Mithat
Published: May 2015

We analyze the resurgence properties of finite-dimensional exponential integrals which are prototypes for partition functions in quantum field theories. In these simple examples, we demonstrate that perturbation theory, even at arbitrarily weak coupling, fails as the argument of the coupling constant is varied. It is well-known that perturbation theory also fails at stronger coupling. We show that these two failures are actually intimately related. The formalism of resurgent transseries, which takes into account global analytic continuation properties, fixes both problems and provides an arbitrarily accurate description of exact result for any value of coupling. This means that strong coupling results can be deduced by using merely weak coupling data. Finally, we give another perspective on resurgence theory by showing that the monodromy properties of the weak coupling results are in precise agreement with the monodromy properties of the strong-coupling expansions, obtained using analysis of the holomorphy structure of Picard-Fuchs equations.
High-fidelity simulations of the lobe-and-cleft structures and the deposition map in particle-driven gravity currents
Authors: Espath L. F. R. , Pinto L. C. , Laizet S. , Silvestrini J. H.
Published: May 2015

The evolution of a mono-disperse gravity current in the lock-exchange configuration is investigated by means of direct numerical simulations for various Reynolds numbers and settling velocities for the deposition. We limit our investigations to gravity currents over a flat bed in which density differences are small enough for the Boussinesq approximation to be valid. The concentration of particles is described in an Eulerian fashion by using a transport equation combined with the incompressible Navier-Stokes equations. The most interesting results can be summarized as follows: (i) the settling velocity is affecting the streamwise vortices at the head of the current with a substantial reduction of their size when the settling velocity is increased; (ii) when the Reynolds number is increased the lobe-and-cleft structures are merging more frequently and earlier in time, suggesting a strong Reynolds number dependence for the spatio-temporal evolution of the head of the current; (iii) the temporal imprint of the lobe-and-cleft structures can be recovered from the deposition map, suggesting that the deposition pattern is defined purely and exclusively by the structures at the front of the current.
Josephson phase diffusion in the superconducting quantum interference device ratchet
Authors: Spiechowicz Jakub , Łuczka Jerzy
Published: May 2015

We study diffusion of the Josephson phase in the asymmetric superconducting quantum interference device (SQUID) subjected to a time-periodic current and pierced by an external magnetic flux. We analyze a relation between phase diffusion and quality of transport characterized by the dc voltage across the SQUID and efficiency of the device. In doing so, we concentrate on the previously reported regime [J. Spiechowicz and J. Łuczka, New J. Phys. 17, 023054 (2015)] for which efficiency of the SQUID attains a global maximum. For long times, the mean-square displacement of the phase is a linear function of time, meaning that diffusion is normal. Its coefficient is small indicating rather regular phase evolution. However, it can be magnified several times by tailoring experimentally accessible parameters like amplitudes of the ac current or external magnetic flux. Finally, we prove that in the deterministic limit this regime is essentially non-chaotic and possesses an unexpected simplicity of attractors.
Effects of energetic coherent motions on the power and wake of an axial-flow turbine
Authors: Chamorro L. P. , Hill C. , Neary V. S. , Gunawan B. , Arndt R. E. A. , Sotiropoulos F.
Published: May 2015

A laboratory experiment examined the effects of energetic coherent motions on the structure of the wake and power fluctuations generated by a model axial-flow hydrokinetic turbine. The model turbine was placed in an open-channel flow and operated under subcritical conditions. The incoming flow was locally perturbed with vertically oriented cylinders of various diameters. An array of three acoustic Doppler velocimeters aligned in the cross-stream direction and a torque transducer were used to collect high-resolution and synchronous measurements of the three-velocity components of the incoming and wake flow as well as the turbine power. A strong scale-to-scale interaction between the large-scale and broadband turbulence shed by the cylinders and the turbine power revealed how the turbulence structure modulates the turbine behavior. In particular, the response of the turbine to the distinctive von Kármán-type vortices shed from the cylinders highlighted this phenomenon. The mean and fluctuating characteristics of the turbine wake are shown to be very sensitive to the energetic motions present in the flow. Tip vortices were substantially dampened and the near-field mean wake recovery accelerated in the presence of energetic motions in the flow. Strong coherent motions are shown to be more effective than turbulence levels for triggering the break-up of the spiral structure of the tip-vortices.
Simulation of micro-magnet stray-field dynamics for spin qubit manipulation
Authors: Neumann R. , Schreiber L. R.
Published: May 2015

High-fidelity control and unprecedented long dephasing times in silicon-based single spin qubits have recently confirmed the prospects of solid-state quantum computation. We investigate the feasibility of using a micro-magnet stray field for all-electrical, addressable spin qubit control in a Si/SiGe double quantum dot. For a micro-magnet geometry optimized for high Rabi-frequency, addressability, and robustness to fabrication misalignment as previously demonstrated by Yoneda et al. [Phys. Rev. Lett. 113, 267601 (2014)], we simulate the qubit decoherence due to magnetic stray-field fluctuations, which may dominate in nuclear spin-free systems, e.g., quantum dots in Si/SiGe, Si-MOS structures and (bilayer) graphene. With calculated Rabi-frequencies of 15 MHz, a qubit addressability error below 10−3 is achievable. Magnetic fluctuations from a micro-magnet limits the spin relaxation time to T1 ≳ 3 s, while pure spin dephasing is negligible. Our results show that micro-magnets are a promising tool for spin qubit computation in nuclear spin-free systems.
Disorder-induced structural transitions in topological insulating Ge-Sb-Te compounds
Authors: Kim Jeongwoo , Jhi Seung-Hoon
Published: May 2015

The mechanism for the fast switching between amorphous, metastable, and crystalline structures in chalcogenide phase-change materials has been a long-standing puzzle. Based on first-principles calculations, we study the atomic and electronic properties of metastable Ge2Sb2Te5 and investigate the atomic disorder to understand the transition between crystalline hexagonal and cubic structures. In addition, we study the topological insulating property embedded in these compounds and its evolution upon structural changes and atomic disorder. We also discuss the role of the surface-like states arising from the topological insulating property in the metal-insulator transition observed in the hexagonal structure.
Hysteresis and change of transition temperature in thin films of Fe{[Me2Pyrz]3BH}2, a new sublimable spin-crossover molecule
Authors: Davesne V. , Gruber M. , Studniarek M. , Doh W. H. , Zafeiratos S. , Joly L. , Sirotti F. , Silly M. G. , Gaspar A. B. , Real J. A. , Schmerber G. , Bowen M. , Weber W. , Boukari S. , Da Costa V. , Arabski J. , Wulfhekel W. , Beaurepaire E.
Published: May 2015

Thin films of the spin-crossover (SCO) molecule Fe{[Me2Pyrz]3BH}2 (Fe-pyrz) were sublimed on Si/SiO2 and quartz substrates, and their properties investigated by X-ray absorption and photoemission spectroscopies, optical absorption, atomic force microscopy, and superconducting quantum interference device. Contrary to the previously studied Fe(phen)2(NCS)2, the films are not smooth but granular. The thin films qualitatively retain the typical SCO properties of the powder sample (SCO, thermal hysteresis, soft X-ray induced excited spin-state trapping, and light induced excited spin-state trapping) but present intriguing variations even in micrometer-thick films: the transition temperature decreases when the thickness is decreased, and the hysteresis is affected. We explain this behavior in the light of recent studies focusing on the role of surface energy in the thermodynamics of the spin transition in nano-structures. In the high-spin state at room temperature, the films have a large optical gap (∼5 eV), decreasing at thickness below 50 nm, possibly due to film morphology.
Perspective: Single polymer mechanics across the force regimes
Authors: Saleh Omar A.
Published: May 2015

I review theoretical and experimental results on the force-extension response of single polymers, with a focus on scaling pictures of low-force elastic regimes, and recent measurements of synthetic and biological chains that explore those regimes. The mechanical response of single polymers is an old theoretical problem whose exploration was instigated by the curious thermomechanical behavior of rubber. Up until the 1990s, the main utility of those calculations was to explain bulk material mechanics. However, in that decade, it became possible to directly test the calculations through high-precision single-chain stretching experiments (i.e., force spectroscopy). I present five major single-chain elasticity models, including scaling results based on blob-chain models, along with analytic results based on linear response theory, and those based on freely jointed chain or worm-like chain structure. Each model is discussed in terms of the regime of force for which it holds, along with the status of its rigorous assessment with experiment. Finally, I show how the experiments can provide new insight into polymer structure itself, with particular emphasis on polyelectrolytes.
Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices
Authors: Kim Myung Ju , Jeon Dong Su , Park Ju Hyun , Kim Tae Geun
Published: May 2015

This paper reports the bipolar resistive switching characteristics of TaNx-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from −0.82 V to −0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>105 s) and pulse-switching endurance (>106 cycles) properties. These results indicate that TaNx-based ReRAM devices have a potential for future nonvolatile memory devices.
Observation of large low temperature magnetocaloric effect in HoCu2
Authors: Karmakar S. K. , Giri S. , Majumdar S.
Published: May 2015

We report the observation of large low temperature magnetocaloric effect and magnetoresistance in the rare-earth based intermetallic compound HoCu2. The compound undergoes an antiferromagnetic type ordering below about TN = 10.5 K, which is second order in nature. The magnetocaloric effect in terms of entropy change under the application of 50 kOe of field is found to have a maximum value of −19.3 J kg−1 K−1 peaking around TN, and an appreciable value of relative cooling power of 268 J kg−1 was associated with it. The sample also shows giant negative magnetoresistance with its value as high as −36.5% around TN for 50 kOe of field. Field induced second order metamagnetic transition is found to be responsible for the observed magnetocaloric and magnetoresistance behaviors in the sample. The sample is devoid of any thermal or field hysteresis by virtue of the second order nature of the transitions, which enables us to exploit large reversible magnetic cooling at cryogenic temperatures.
Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells
Authors: Wan Yimao , Bullock James , Cuevas Andres
Published: May 2015

This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω·cm and n-type 1.0 Ω·cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 Ω/sq boron-diffused p+ and 120 Ω/sq phosphorus-diffused n+ c-Si, respectively. Capacitance–voltage measurements reveal a negative fixed insulator charge density of −1.8 × 1012 cm−2 for the Ta2O5 film and −1.0 × 1012 cm−2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.
Thermal effects on transverse domain wall dynamics in magnetic nanowires
Authors: Leliaert J. , Van de Wiele B. , Vandermeulen J. , Coene A. , Vansteenkiste A. , Laurson L. , Durin G. , Van Waeyenberge B. , Dupré L.
Published: May 2015

Magnetic domain walls are proposed as data carriers in future spintronic devices, whose reliability depends on a complete understanding of the domain wall motion. Applications based on an accurate positioning of domain walls are inevitably influenced by thermal fluctuations. In this letter, we present a micromagnetic study of the thermal effects on this motion. As spin-polarized currents are the most used driving mechanism for domain walls, we have included this in our analysis. Our results show that at finite temperatures, the domain wall velocity has a drift and diffusion component, which are in excellent agreement with the theoretical values obtained from a generalized 1D model. The drift and diffusion component are independent of each other in perfect nanowires, and the mean square displacement scales linearly with time and temperature.
Impact of crystalline defects and size on X-ray line broadening: A phenomenological approach for tetragonal SnO2 nanocrystals
Authors: Muhammed Shafi P. , Chandra Bose A.
Published: May 2015

Nanocrystalline tin oxide (SnO2) powders with different grain size were prepared by chemical precipitation method. The reaction was carried out by varying the period of hydrolysis and the as-prepared samples were annealed at different temperatures. The samples were characterized using X-ray powder diffractometer and transmission electron microscopy. The microstrain and crystallite size were calculated for all the samples by using Williamson-Hall (W-H) models namely, isotropic strain model (ISM), anisotropic strain model (ASM) and uniform deformation energy density model (UDEDM). The morphology and particle size were determined using TEM micrographs. The directional dependant young’s modulus was modified as an equation relating elastic compliances (sij) and Miller indices of the lattice plane (hkl) for tetragonal crystal system and also the equation for elastic compliance in terms of stiffness constants was derived. The changes in crystallite size and microstrain due to lattice defects were observed while varying the hydrolysis time and the annealing temperature. The dependence of crystallite size on lattice strain was studied. The results were correlated with the available studies on electrical properties using impedance spectroscopy.
Observation of magnetic domain structure in anatase (Ti,Co)O2 thin film at room temperature
Authors: Krasienapibal Thantip S. , Inoue Shun , Fukumura Tomoteru , Hasegawa Tetsuya
Published: May 2015

Magnetic domain structures in anatase (Ti,Co)O2 (001) epitaxial thin films were observed at room temperature. Magnetic force microscopy in vacuum enabled to observe submicrometer-sized maze domain. Variation of magnetic domain structure as functions of carrier density and Co content was in accordance with that of macroscopic magnetization representing close relationship between the bulk magnetism and magnetic domain structure. With increasing carrier density and/or Co content, the magnetic domain became larger with larger magnetic force signal mostly, where the ferromagnetic transition at carrier density of ∼2 × 1019 cm−3 was observed as an emergence of magnetic domain structure. Micromagnetic parameters were evaluated as functions of carrier density and Co content.
Large and reversible elastocaloric effect in dual-phase Ni54Fe19Ga27 superelastic alloys
Authors: Xu Yang , Lu Binfeng , Sun Wen , Yan Aru , Liu Jian
Published: May 2015

In this work, we report elastocaloric effect (eCE) in Ni-Fe-Ga polycrystalline alloys. By application of a uniaxial compressive stress of 170 MPa at 298 K, a large and recoverable temperature change of 4 K has been obtained in precipitates-containing Ni54Fe19Ga27 alloys. The degradation of eCE is insensitive to 100 loading-unloading cycles. In comparison, the loss of mechanical integrity occurs in the single-phase alloy suffering from only 10 superelastic cycles, implying a short fatigue life. Good mechanical properties, large and equivalent adiabatic temperature change (ΔT) under loading-unloading cycle render dual-phase Ni-Fe-Ga promising candidate materials for solid-state mechanical cooling application at ambient conditions.
Sapwood allocation in tropical trees: a test of hypotheses
Authors: Schippers Peter , Vlam Mart , Zuidema Pieter A. , Sterck Frank
Published: May 2015

Carbon allocation to sapwood in tropical canopy trees is a key process determining forest carbon sequestration, and is at the heart of tree growth and dynamic global vegetation models (DGVM). Several allocation hypotheses exist including those applying assumptions on fixed allocation, pipe model, and hierarchical allocation between plant organs. We use a tree growth model (IBTREE) to evaluate these hypotheses by comparing simulated sapwood growth with 30 year tree ring records of the tropical long-lived tree Toona ciliata M. Roem. in Thailand. Simulated annual variation in wood production varied among hypotheses. Observed and simulated growth patterns matched most closely (r2 = 0.70) when hierarchical allocation was implemented, with low priority for sapwood. This allocation method showed realistic results with respect to reserve dynamics, partitioning and productivity and was the only one able to capture the large annual variation in tree ring width. Consequently, this method might also explain the large temporal variation in diameter growth and the occurrence of missing rings often encountered in other tropical tree species. Overall, our results show that sapwood growth is highly sensitive to allocation principles, and that allocation assumptions may greatly influence estimated carbon sequestration of tropical forests under climatic change.
Involvement of G9A-like protein (GLP) in the development of mouse preimplantation embryos in vitro
Authors: Huang Xian-Ju , Ma Xueshan , Wang Xuguang , Zhou Xiaolong , Li Juan , Sun Shao-Chen , Liu Honglin
Published: May 2015

G9A-like protein (GLP) plays an important role in mouse early embryonic development. Glp-deficient embryos exhibit severe growth retardation and defects that lead to lethality at approximately Embryonic Day 9.5. In the present study we investigated the effect of microinjection of Glp-specific short interference (si) RNA into mouse zygotes on in vitro embryonic development. Knockdown of Glp induced abnormal embryonic development and reduced blastocyst formation. Expression of the pluripotency markers octamer-binding transcription factor 4 (Oct4), SRY (sex determining region Y)-box 2 (Sox2) and Nanog was also significantly decreased in Glp-deficient embryos. The apoptotic index and expression of two pro-apoptotic genes, namely Caspase 3 and Caspase 9, were increased in Glp-deficient embryos. Moreover, methylation levels of dimethylated H3K9 (H3K9me2) were decreased in Glp-knockdown embryos. In conclusion, the results of the present study suggest that Glp deficiency suppresses H3K9me2 modification and hinders mouse embryo development in vitro.
The discovery of the unexpected
Authors: Labov William
Published: May 2015

The history of sociolinguistic research leads us to expect certain patterns of variation by social class, age and gender, but as the field expands to new societies with different social structures we often encounter unexpected results. Such findings can have great value in leading to higher level generalizations. Cases are cited of unexpected gender variation in studies of rural communities in Spain, Egypt, central India and south China where ethnographic observation leads to a better understanding of what seemed at first to be anomalous results.
A sociotonetic study of Lalo tone split in progress
Authors: Yang Cathryn , Stanford James N. , Yang Zhengyu
Published: May 2015

Since Labov’s early work (e.g., 1963, 1966), sociolinguists have frequently examined change in progress on the segmental level, but much less is known about tone change in progress. The present study finds evidence of a tone split in progress in Lalo, a Tibeto-Burman language of China. While many of the world’s tone languages show historical evidence of tone splits, to our knowledge this is the first time that a tone split has been observed while it is occurring, making it possible to closely examine phonological, social, and perceptual factors. In this sociotonetic study of Lalo, 2,938 tone tokens were extracted from recordings of 38 speakers and analyzed in terms of age, sex, and educational level. Multifactorial analyses show that the temporal extent of voiced stops’ depression of Tone 1 F0 is increasing in apparent time, especially among women, while VOT of voiced stops is decreasing as educational levels improve, giving speakers more contact with Mandarin Chinese. The same 38 speakers were also given a perceptual identification task in which F0 was systematically adjusted. Mixed-effects modeling showed that listeners used multiple acoustic cues (consonant voicing, F0 onset, and F0 shape) to identify the voiced initial. These findings suggest that Lalo is undergoing a tone split that follows Beddor’s (2009) coarticulatory path to sound change.
Genetic Population Structure of Black Drum in U.S. Waters
Authors: Leidig Jacqueline M. , Shervette Virginia R. , McDonough Christopher J. , Darden Tanya L.
Published: May 2015

The Black Drum Pogonias cromis is an estuarine-dependent fish that supports recreational and commercial fisheries throughout its range along the U.S. Atlantic coast and Gulf of Mexico (GOM) coast. We used nuclear microsatellite markers and samples collected from multiple locations along both the U.S. Atlantic and GOM coasts to evaluate the stock structure of Black Drum and to examine small-scale spatial genetic population structure along the U.S. Atlantic coast. As no microsatellite primers had been developed for Black Drum, primers for Spotted Seatrout Cynoscion nebulosus and Red Drum Sciaenops ocellatus were screened, selected, and optimized for use with Black Drum DNA. Six polymorphic loci were identified and used to genotype samples. Results suggested (1) significant genetic divergence between Black Drum populations from the U.S. Atlantic coast and the GOM coast; and (2) either recent or current gene flow between the two regions. Along the U.S. Atlantic coast, there appeared to be weak but significant genetic divergence among Black Drum from southern states, specifically between individuals from the Carolinas and Florida. An isolation-by-distance pattern was also observed for Black Drum from North Carolina to Florida. On a larger scale, results suggested a lack of genetic divergence between individuals from Delaware and Virginia and those from the southern Atlantic states, which may be attributable to the life history patterns of Black Drum. Our results support the management of Black Drum in U.S. waters as two separate stocks: Atlantic and GOM. The results also support the management of Black Drum along the U.S. Atlantic coast as a single unified stock and indicate the need for common management regulations among the Atlantic states.

Received August 26, 2014; accepted February 4, 2015
Effects of Lake Surface Elevation on Shoreline-Spawning Lost River Suckers
Authors: Burdick Summer M. , Hewitt David A. , Rasmussen Josh E. , Hayes Brian S. , Janney Eric C. , Harris Alta C.
Published: May 2015

We analyzed remote detection data from PIT-tagged Lost River Suckers Deltistes luxatus at four shoreline spawning areas in Upper Klamath Lake, Oregon, to determine whether spawning of this endangered species was affected by low water levels. Our investigation was motivated by the observation that the surface elevation of the lake during the 2010 spawning season was the lowest in 38 years. Irrigation withdrawals in 2009 that were not replenished by subsequent winter–spring inflows caused a reduction in available shoreline spawning habitat in 2010. We compared metrics of skipped spawning, movement among spawning areas, and spawning duration across 8 years (2006–2013) that had contrasting spring water levels. Some aspects of sucker spawning were similar in all years, including few individuals straying from the shoreline areas to spawning locations in lake tributaries and consistent effects of increasing water temperatures on the accumulation of fish at the spawning areas. During the extreme low water year of 2010, 14% fewer female and 8% fewer male suckers joined the shoreline spawning aggregation than in the other years. Both males and females visited fewer spawning areas within Upper Klamath Lake in 2010 than in other years, and the median duration at spawning areas in 2010 was at least 36% shorter for females and 20% shorter for males relative to other years. Given the imperiled status of the species and the declining abundance of the population in Upper Klamath Lake, any reduction in spawning success and egg production could negatively impact recovery efforts. Our results indicate that lake surface elevations above 1,262.3–1,262.5 m would be unlikely to limit the number of spawning fish and overall egg production.

Received May 16, 2014; accepted January 29, 2015