Are we over treating Pineal Parenchymal tumour with intermediate differentiation? Assessing the role of localised radiation therapy and literature review.

Pineal Parenchymal tumour with intermediate differentiation (PPTID) is a rare disorder, first classified by World Health Organisation in 2000. There are very few published data available and optimal management is yet to be determined. Management has varied from surgery alone to craniospinal radiotherapy with or without chemotherapy. We present our experience of PPTID treated with radiotherapy alone. We conducted a retrospective review of patients who were diagnosed with PPTID and treated with radiation therapy at our institute from 2010 onwards. Between January 2010 to January 2013, 5 patients of PPTID were treated at our institute. Median age is 44 (range 24-62). All patients had preoperative MRI scan of brain and spine. Imaging did not identify any spinal dissemination. None of the patients underwent a gross total resection, due to the tumour location and technical difficulties. All patients were treated with external beam radiation therapy to primary lesion only with a dose of 54 Gy in 30 fractions after surgery. 4 patients had good partial response and the remaining 1 has stable disease. After 21.4 months of median follow up no disease recurrence was reported. So far there is no evidence of cerebral white matter abnormalities on MRI scan or neurocognitive disorders. Our experience indicated that localised radiation therapy could be an effective treatment strategy for PPTID, considering the long natural course of the disease and the late adverse effects of intensive treatment.

Pathway to the piezoelectronic transduction logic device.

The piezoelectronic transistor (PET) has been proposed as a transduction device not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator-metal transition, thereby achieving multigigahertz switching speeds, as predicted by modeling, at lower power than the comparable generation field effect transistor (FET). Here, the fabrication and measurement of the first physical PET devices are reported, showing both on/off switching and cycling. The results demonstrate the realization of a stress-based transduction principle, representing the early steps on a developmental pathway to PET technology with potential to contribute to the IT industry.

Higher order harmonic detection for exploring nonlinear interactions with nanoscale resolution.

Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, insight into the nonlinear behavior can be gleaned through exploration of higher order harmonics. Here, a method using band excitation scanning probe microscopy (SPM) to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The technique is demonstrated by probing the first three harmonics of strain for a Pb(Zr(1-x)Ti(x))O3 (PZT) ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, measurements of the second harmonic reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of n(th) order harmonic SPM detection methods in exploring nonlinear phenomena in nanoscale materials.

Substrate clamping effects on irreversible domain wall dynamics in lead zirconate titanate thin films.

The role of long-range strain interactions on domain wall dynamics is explored through macroscopic and local measurements of nonlinear behavior in mechanically clamped and released polycrystalline lead zirconate-titanate (PZT) films. Released films show a dramatic change in the global dielectric nonlinearity and its frequency dependence as a function of mechanical clamping. Furthermore, we observe a transition from strong clustering of the nonlinear response for the clamped case to almost uniform nonlinearity for the released film. This behavior is ascribed to increased mobility of domain walls. These results suggest the dominant role of collective strain interactions mediated by the local and global mechanical boundary conditions on the domain wall dynamics. The work presented in this Letter demonstrates that measurements on clamped films may considerably underestimate the piezoelectric coefficients and coupling constants of released structures used in microelectromechanical systems, energy harvesting systems, and microrobots.

Giant piezoelectricity on Si for hyperactive MEMS.

Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.

Collective dynamics underpins Rayleigh behavior in disordered polycrystalline ferroelectrics.

Nanoscale and mesoscopic disorder and associated local hysteretic responses underpin the unique properties of spin and cluster glasses, phase-separated oxides, polycrystalline ferroelectrics, and ferromagnets alike. Despite the rich history of the field, the relationship between the statistical descriptors of hysteresis behavior such as Preisach density, and micro and nanostructure has remained elusive. By using polycrystalline ferroelectric capacitors as a model system, we now report quantitative nonlinearity measurements in 0.025-1 microm(3) volumes, approximately 10(6) times smaller than previously possible. We discover that the onset of nonlinear behavior with thickness proceeds through formation and increase of areal density of micron-scale regions with large nonlinear response embedded in a more weakly nonlinear matrix. This observation indicates that large-scale collective domain wall dynamics, as opposed to motion of noninteracting walls, underpins Rayleigh behavior in disordered ferroelectrics. The measurements provide evidence for the existence and extent of the domain avalanches in ferroelectric materials, forcing us to rethink 100-year old paradigms.

(111)(p) microtwinning in SrRuO(3) thin films on (001)(p) LaAlO(3).

SrRuO(3) (SRO) thin films grown on (001)(p) (p = pseudocubic) oriented LaAlO(3) (LAO) by pulsed laser deposition have been characterized using transmission electron microscopy. Observations along the 100(p) directions suggests that although the SRO layer maintains a pseudocube-to-pseudocube orientation relationship with the underlying LAO substrate, it has a ferroelastic domain structure associated with a transformation on cooling to room temperature to an orthorhombic Pbnm phase (a(-)a(-)c(+) Glazer tilt system). In addition, extra diffraction spots located at +/-1/6(ooo)(p) and +/-1/3(ooo)(p) (where ;o' indicates an index with an odd number) positions were obtained in 110(p) zone-axis diffraction patterns. These were attributed to the existence of high-density twins on {111}(p) pseudocubic planes within the SrRuO(3) films rather than to more conventional mechanisms for the generation of superstructure reflections.

Disorder identification in hysteresis data: recognition analysis of the random-bond-random-field Ising model.

An approach for the direct identification of disorder type and strength in physical systems based on recognition analysis of hysteresis loop shape is developed. A large number of theoretical examples uniformly distributed in the parameter space of the system is generated and is decorrelated using principal component analysis (PCA). The PCA components are used to train a feed-forward neural network using the model parameters as targets. The trained network is used to analyze hysteresis loops for the investigated system. The approach is demonstrated using a 2D random-bond-random-field Ising model, and polarization switching in polycrystalline ferroelectric capacitors.

Ferroelectricity in ultrathin BaTiO3 films: probing the size effect by ultraviolet Raman spectroscopy.

We demonstrate the dramatic effect of film thickness on the ferroelectric phase transition temperature Tc in strained BaTiO3 films grown on SrTiO3 substrates. Using variable-temperature ultraviolet Raman spectroscopy enables measuring Tc in films as thin as 1.6 nm, and a film thickness variation from 1.6 to 10 nm leads to Tc tuning from 70 to about 925 K. Raman data are consistent with synchrotron x-ray scattering results, which indicate the presence of 180 degrees domains below Tc, and thermodynamic phase-field model calculations of Tc as a function of thickness.

Spatially resolved spectroscopic mapping of polarization reversal in polycrystalline ferroelectric films: crossing the resolution barrier.

The mesoscopic reversible and irreversible polarization dynamics in polycrystalline PZT thin film capacitors are studied using local spectroscopic mapping and macroscopic first-order reversal curve measurements. The transition from a regime of short range domain wall motion to the formation of mesoscopic clusters to complete switching is observed. The fractal dimension of the clusters is consistent with the random-bond disorder model. The combination of macroscopic and local measurements allows the characteristics length scales corresponding to the transition from Rayleigh to Preisach behaviors and onset of macroscopic averaging to be determined.

CMOS Ultrasound Transceiver Chip for High-Resolution Ultrasonic Imaging Systems.

The proposed CMOS ultrasound transceiver chip will enable the development of portable high resolution, high-frequency ultrasonic imaging systems. The transceiver chip is designed for close-coupled MEMS transducer arrays which operate with a 3.3-V power supply. In addition, a transmit digital beamforming system architecture is supported in this work. A prototype chip containing 16 receive and transmit channels with preamplifiers, time-gain compensation amplifiers, a multiplexed analog-to-digital converter with 3 kB of on-chip SRAM, and 50-MHz resolution time delayed excitation pulse generators has been fabricated. By utilizing a shared A/D converter architecture, the number of A/D converter and SRAM is cut down to one, unlike typical digital beamforming systems which need 16 A/D converters for 16 receive channels. The chip was fabricated in a 0.35-mum standard CMOS process. The chip size is 10 mm(2), and its average power consumption in receive mode is approximately 270 mW with a 3.3-V power supply. The transceiver chip specifications and designs are described, as well as measured results of each transceiver component and initial pulse-echo experimental results are presented.

Magnetic color symmetry of lattice rotations in a diamagnetic material.

Oxygen octahedral rotations are the most common phase transitions in perovskite crystal structures. Here we show that the color symmetry of such pure elastic distortions is isomorphic to magnetic point groups, which allows their probing through distinguishing polar versus magnetic symmetry. We demonstrate this isomorphism using nonlinear optical probing of the octahedral rotational transition in a compressively strained SrTiO3 thin film that exhibits ferroelectric (4mm) and antiferrodistortive (4{'}mm{'}) phases evolving through independent phase transitions. The approach has broader applicability for probing materials with lattice rotations that can be mapped to color groups.

Dielectric and electromechanical properties of barium titanate single crystals grown by templated grain growth.

Single crystals of BaTiO(3) were grown by templated grain growth (TGG). TGG involves contacting a single crystal "template" to a sintered polycrystalline matrix, then heating the assemblage to a temperature that promotes the migration of the single crystal boundary through the matrix. In this investigation the properties of millimeter-sized, plate-shaped and bar-shaped, single crystals of BaTiO(3) grown by TGG were examined in order to compare the results to single crystals grown by conventional methods. A dielectric constant, epsilon(33)(T)/epsilon(0), of 260, polarizations of P(R)~16 microC/cm(2) and P(sat)~21.5 microC/cm(2), electromechanical coupling coefficients of k(33)~0.51 and k(31)~0.18, and a piezoelectric coefficient of d(33)~140 pC/N were achieved. Entrapped porosity in the crystals made fully poling the crystals difficult.

Cerebral venous thrombosis occurring during an ectopic pregnancy and complicated by intracranial hypertension.

Thrombosis of the cerebral dural sinuses and veins has been described since the early 19th century. Clinically the process is characterised by diverse symptomatology and physical findings and in spite of advances in diagnostic radiological techniques it remains an under-recognised condition. It has been most commonly associated with sepsis, trauma, pregnancy, the puerperium and many other hypercoagulable states. We describe an apparently unique case of sagittal sinus thrombosis occurring during an ectopic pregnancy. This was subsequently complicated by intracranial hypertension in spite of clinical improvement and magnetic resonance imaging (MRI) evidence suggesting a return of venous patency. The clinical presentation, radiological features and management is discussed.

Serum neurone-specific enolase as an indicator of stroke volume.

Serum neurone-specific enolase (NSE) and computerized tomography (CT) stroke volume were compared in patients admitted within 24 h of an acute stroke. Serum samples were obtained on admission and daily for the next 4 days. Of 163 patients, CT scans revealed 25 with intracerebral haemorrhages, one haemorrhagic infarct and 83 measurable acute infarcts. The serum NSE levels of those with infarcts was significantly higher than in those with haemorrhages at 48 (P = 0.0003) and 72 h (P = 0.04). The maximum serum NSE value tended to occur later in those with large infarcts (P = 0.0035). There was a significant correlation between infarct volume and serum NSE at 48 h (r = 0.27, P = 0.015) and 96 h (r = 0.27, P = 0.015) and with the maximum serum NSE over the 4 days (r = 0.36, P = 0.001). There was no significant correlation between haemorrhage volume and NSE. In conclusion, serum NSE may be a useful marker of infarct volume in studies of therapy in acute stroke. Sampling for NSE should continue, at least in those with large infarcts, for longer than 4 days. Serum NSE cannot be used to distinguish between haemorrhage and infarction in patients with an acute stroke.

Serum neurone specific enolase (NSE) levels as an indicator of neuronal damage in patients with cerebral infarction.

A radioimmunoassay has been developed and used to measure serum neurone specific enolase (NSE) concentrations in 24 patients, following cerebral infarction. A significant correlation between cerebral infarct volume and maximum serum NSE concentration was observed (P = 0.047). Serum NSE was also assayed at times 24, 48, 72 and 96 h post ictus. At 72 h a significant correlation existed between serum NSE levels and infarct volume (P = 0.012), and levels appeared to be approaching statistical significance at 48 h (P = 0.067). No correlation existed at 24 and 96 h. In addition serum concentrations of NSE were compared to clinical outcome as determined by the Glasgow Outcome Score. Using the Mann-Whitney U test, there was no significant difference in maximum NSE level between patients graded 1-3 on the Glasgow Outcome Score and those graded 4 and 5. However, further studies are required on a larger population to more completely assess this. NSE may prove to be a useful marker of neuronal damage in the study of stroke, with particular application in the assessment of treatment.

The role of diencephalic pathology in human memory disorder. Evidence from a penetrating paranasal brain injury.

A patient (B.J.) is reported who developed severe memory impairment following a penetrating brain injury caused by a snooker cue which entered through his left nostril into the basal regions of the brain. Initially, his memory disorder had the clinical features of a dense amnesic syndrome, with both anterograde and retrograde amnesia, but B.J. subsequently showed significant recovery of memory function. Formal memory testing was carried out 21 months after injury. This demonstrated marked verbal memory impairment, as severe as that seen in patients with the amnesic syndrome. On nonverbal memory tests, his impairment was relatively mild and patchy. His retrograde amnesia had regressed mainly to affect a 6 month period before the injury. On other cognitive tasks, he performed at an average or above average level, and there was no neuropsychological evidence of frontal lobe dysfunction. Neuroradiological investigations at various stages after his injury failed to demonstrate a lesion in any of the thalamic nuclei. Magnetic resonance imaging showed a lesion in the hypothalamus in the region of the mamillary bodies. Our study demonstrates that marked, relatively focal, memory disorder after diencephalic injury can occur without direct pathology to the body of the thalamus. It also indicates that structures in or adjacent to the hypothalamus, such as the mamillary bodies, may play a more important role in human memory functioning than has hitherto been considered.