Wedge Region Research Articles

Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR

ABSTRACTA new upper limit on the 21 cm signal power spectrum at a redshift of z ≈ 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally smooth gain-calibration, Gaussian Process Regression (GPR) foreground mitigation and optimally weighted power spectrum inference. Previously seen ‘excess power’ due to spectral structure in the gain solutions has markedly reduced but some excess power still remains with a spectral correlation distinct from thermal noise. This excess has a spectral coherence scale of 0.25–0.45 MHz and is partially correlated between nights, especially in the foreground wedge region. The correlation is stronger between nights covering similar local sidereal times. A best 2-σ upper limit of $\Delta ^2_{21} \lt (73)^2\, \mathrm{mK^2}$ at $k = 0.075\, \mathrm{h\, cMpc^{-1}}$ is found, an improvement by a factor ≈8 in power compared to the previously reported upper limit. The remaining excess power could be due to residual foreground emission from sources or diffuse emission far away from the phase centre, polarization leakage, chromatic calibration errors, ionosphere, or low-level radiofrequency interference. We discuss future improvements to the signal processing chain that can further reduce or even eliminate these causes of excess power.

Influence of wedge shape on the performance of air foil thrust bearings

PurposeThe purpose of this paper is to investigate the effect of different wedge shapes on the performance of air foil thrust bearing (AFTB).Design/methodology/approachDuring the study, a bump foil stiffness model considering slip deformation and a two-dimensional sheet top foil model is established, and the Reynolds equation and film thickness equation is solved using the finite difference method and finite element method. The static performance such as load carrying capacity, friction torque and power loss of AFTB under different taper parameters is obtained. The influence of different pitch ratio, film thickness ratio and wedge shapes on the bearing characteristics is studied.FindingsThere is an optimal height and a pitch ratio for the taper of AFTB with certain tile number. Compared to the plane and concave wedge shape, the upper convex shape can enhance the convergence effect of the wedge region, increase the effective film pressure distribution area of the bearing and reduce the local concentrated load of the top foil, which is more conductive to the increase of load capacity.Originality/valueThe wedge shape parameters bring a fundamental difference in the static performance of AFTB. The results are expected to be helpful to bearing designers, researchers and academicians concerned.

A note on the aerodynamic splashing of droplets

When a drop of a low-viscosity liquid of radius $R$ impacts against an inclined smooth solid substrate at a velocity $V$, a liquid sheet of thickness $H_{t}\ll R$ is expelled at a velocity $V_{t}\gg V$. If the impact velocity is such that $V>V^{\ast }$, with $V^{\ast }$ the critical velocity for splashing, the edge of the expanding liquid sheet lifts off from the wall as a consequence of the gas lubrication force at the wedge region created between the advancing liquid front and the substrate. Here we show that the magnitude of the gas lubrication force is limited by the values of the slip length $\ell _{\unicode[STIX]{x1D707}}$ at the gas–liquid interface and of the slip length $\ell _{g}\propto \unicode[STIX]{x1D706}$ at the solid, with $\unicode[STIX]{x1D706}$ the mean free path of gas molecules. We demonstrate that the splashing regime changes depending on the value of the ratio $\ell _{\unicode[STIX]{x1D707}}/\ell _{g}$ – a fact explaining the spreading–splashing–spreading–splashing transition for a fixed (low) value of the gas pressure as the drop impact velocity increases (Xu et al., Phys. Rev. Lett., vol. 94, 2005, 184505; Hao et al., Phys. Rev. Lett., vol. 122, 2019, 054501). We also provide an expression for $V^{\ast }$ as a function of the inclination angle of the substrate, the drop radius $R$, the material properties of the liquid and the gas, and the mean free path $\unicode[STIX]{x1D706}$, in very good agreement with experiments.

Abstract TMP33: Modulation of Receptor Protein Tyrosine Phosphatase Sigma Promotes Neuroregeneration and Functional Recovery After Ischemic Stroke

Introduction: Due to the limitation in current treatment window for stroke, the development of delayed stroke treatment is needed. The two main cellular processes of neural repair after stroke are axonal sprouting and neurogenesis. Inhibitory chondroitin sulfate proteoglycans (CSPGs) are increased within the glial scar and perineuronal net after ischemic brain injury, which might play a critical role in blocking neuroblasts migration, axonal regrowth and sprouting. Recently, a novel small peptide memetic of the CSPG receptor (PTP σ) wedge region named ISP (Intracellular Sigma Peptide) is generated and has capabilities to target PTP σ and relieve CSPGs inhibition in the models of spinal cord injury. Here, we aimed to determine whether post-stroke ISP treatment could improve functional recovery in a mouse model of ischemia. Methods: Mice were subjected to tMCAO followed by treatment of ISP or vehicle daily for 4 weeks beginning 24h or 7 days post-tMCAO. Motor and sensorimotor functions were measured prior to MCAO and at 1, 2, 3 and 4 weeks post-stroke using locomotion analysis and adhesion removal test. Cognitive function was also assessed with Barnes maze test at 4 weeks post-stroke. Neurogenesis and axonal sprouting was evaluated using genetic labeling and immunohistochemical analysis. Results: Our results show that continuous ISP treatment starting at 24 hours post stroke improves both survival and long-term functional recovery after stroke and 7 day post-stroke treatment improves the functional recovery. Correlated with the improved behavior measurements, immunohistochemical analysis revealed that post-stroke ISP treatment increased the total number of newly generated neuroblast cells migrating towards the peri-infarct area as well as a robust sprouting/regeneration of serotonergic axons around the stroke peri-infarct area. Conclusions: Our data suggest that inhibition of PTP σ/CSPGs signaling by ISP stimulates functional recovery after stroke via promoting neuroblast migration and axonal growth. Pharmacological targeting of the PTP σ/CSPGs interaction is therefore a potential novel therapeutic strategy for stroke treatment, which may provide a prolonged treatment window for improving functional recovery after stroke.

Structural and functional analysis of the nucleotide and DNA binding activities of the human PIF1 helicase.

Pif1 is a multifunctional helicase and DNA processing enzyme that has roles in genome stability. The enzyme is conserved in eukaryotes and also found in some prokaryotes. The functions of human PIF1 (hPIF1) are also critical for survival of certain tumour cell lines during replication stress, making it an important target for cancer therapy. Crystal structures of hPIF1 presented here explore structural events along the chemical reaction coordinate of ATP hydrolysis at an unprecedented level of detail. The structures for the apo as well as the ground and transition states reveal conformational adjustments in defined protein segments that can trigger larger domain movements required for helicase action. Comparisons with the structures of yeast and bacterial Pif1 reveal a conserved ssDNA binding channel in hPIF1 that we show is critical for single-stranded DNA binding during unwinding, but not the binding of G quadruplex DNA. Mutational analysis suggests that while the ssDNA-binding channel is important for helicase activity, it is not used in DNA annealing. Structural differences, in particular in the DNA strand separation wedge region, highlight significant evolutionary divergence of the human PIF1 protein from bacterial and yeast orthologues.

Targeting proteoglycan receptor PTPσ restores sensory function after spinal cord dorsal root injury by activation of Erks/CREB signaling pathway

Dorsal root injury commonly results in irreversible loss of sensory functions because of the limited intrinsic regenerative capacity of adult sensory axons and the growth-inhibitory environment at the dorsal root entry zone (DREZ) between the dorsal root and the spinal cord. Chondroitin sulfate proteoglycans (CSPGs) are the dominant suppressors of axonal regeneration, acting via neuronal receptors including protein tyrosine phosphatase-σ (PTPσ). ISP (Intracellular Sigma Peptide) is a small peptide mimetic of the PTPσ wedge region that has been developed to target PTPσ and relieve CSPG inhibition. Extracellular regulated kinases (Erks) and cAMP response element binding protein (CREB) are signaling molecules downstream of CSPGs and PTPσ; they are expressed in neurons and essential for axon growth. In this study, we observed that ISP administration could promote sensory function restoration in adult rats after dorsal spinal root crush injury. Our results show that systemic ISP administration would not only significantly increase sensory axon regeneration and functional recovery, but also activate Erk and CREB signaling pathway. Furthermore, ISP has also been verified to increase dorsal root ganglion axonal remyelination in vitro. These results suggest that modulation of PTPσ by ISP represents a promising therapeutic strategy for sensory neuronal injuries.

Saltwater-freshwater mixing fluctuation in shallow beach aquifers

Field measurements and numerical simulations demonstrate the existence of an upper saline plume in tidally dominated beaches. The effect of tides on the saltwater-freshwater mixing occurring at both the upper saline plume and lower salt wedge is well understood. However, it is poorly understood whether the tidal driven force acts equally on the mixing behaviours of above two regions and what factors control the mixing fluctuation features. In this study, variable-density, saturated-unsaturated, transient groundwater flow and solute transport numerical models are proposed and performed for saltwater-freshwater mixing subject to tidal forcing on a sloping beach. A range of tidal amplitude, fresh groundwater flux, hydraulic conductivity, beach slope and dispersivity anisotropy are simulated. Based on the time sequential salinity data, the gross mixing features are quantified by computing the spatial moments in three different aspects, namely, the centre point, length and width, and the volume (or area in a two-dimensional case). Simulated salinity distribution varies significantly at saltwater-freshwater interfaces. Mixing characteristics of the upper saline plume greatly differ from those in the salt wedge for both the transient and quasi-steady state. The mixing of the upper saline plume largely inherits the fluctuation characteristics of the sea tide in both the transverse and longitudinal directions when the quasi-steady state is reached. On the other hand, the mixing in the salt wedge is relatively steady and shows little fluctuation. The normalized mixing width and length, mixing volume and the fluctuation amplitude of the mass centre in the upper saline plume are, in general, one-magnitude-order larger than those in the salt wedge region. In the longitudinal direction, tidal amplitude, fresh groundwater flux, hydraulic conductivity and beach slope are significant control factors of fluctuation amplitude. In the transverse direction, tidal amplitude and beach slope are the main control parameters. Very small dispersivity anisotropy (e.g., αL/αT<5) could greatly suppress mixing fluctuation in the longitudinal direction. This work underlines the close connection between the sea tides and the upper saline plume in the aspect of mixing, thereby enhancing understanding of the interplay between tidal oscillations and mixing mechanisms in tidally dominated sloping beach systems.

Structural insights into RNA unwinding and degradation by RNase R.

RNase R is a conserved exoribonuclease in the RNase II family that primarily participates in RNA decay in all kingdoms of life. RNase R degrades duplex RNA with a 3′ overhang, suggesting that it has RNA unwinding activity in addition to its 3′-to-5′ exoribonuclease activity. However, how RNase R coordinates RNA binding with unwinding to degrade RNA remains elusive. Here, we report the crystal structure of a truncated form of Escherichia coli RNase R (residues 87–725) at a resolution of 1.85 Å. Structural comparisons with other RNase II family proteins reveal two open RNA-binding channels in RNase R and suggest a tri-helix ‘wedge’ region in the RNB domain that may induce RNA unwinding. We constructed two tri-helix wedge mutants and they indeed lost their RNA unwinding but not RNA binding or degrading activities. Our results suggest that the duplex RNA with an overhang is bound in the two RNA-binding channels in RNase R. The 3′ overhang is threaded into the active site and the duplex RNA is unwound upon reaching the wedge region during RNA degradation. Thus, RNase R is a proficient enzyme, capable of concurrently binding, unwinding and degrading structured RNA in a highly processive manner during RNA decay.

Episodic growth of fold-thrust belts: Insights from Finite Element Modelling

The sequential development of a fold-thrust belt was investigated using 2D Finite Element Modelling (FEM). The new model results show that a thrust system is typically composed of three distinct regions: the thrust wedge, pre-wedge, and undeformed region. The thrust wedge involves growth that repeats episodically and cyclically. A cycle of wedge building starts as frontal accretion occurs, which is accompanied by a rapid increase in wedge width reducing the taper angle below critical. In response to this, the wedge interior (tracked here by the 50 m displacement position) rapidly propagates forwards into a region of incipient folding. The taper angle progressively increases until it obtains a constant apparent critical value (∼10°). During this period, the wedge experiences significant shortening after a new thrust initiates at the failure front, leading to a decrease in wedge width. Successive widening of the wedge and subsequent shortening and thrusting maintain a reasonably constant taper angle. The fold-thrust belt evolves cyclically, through a combination of rapid advancement of the wedge and subsequent gradual, slow wedge growth. The new model results also highlights that there is clear, although minor, deformation (0–10 m horizontal displacement) in front of the thrust wedge.

Restoration of missing data in limited angle tomography based on Helgason–Ludwig consistency conditions

In limited angle tomography, missing data in an insufficient angular scan will cause streak artifacts in the reconstructed images. Correspondingly, in the frequency domain representation of the imaged object, a double wedge-shaped region is missing. In this paper, we perform a regression in sinogram domain and an image fusion in frequency domain to restore the missing data. We first convert the sinogram restoration problem into a regression problem based on the Helgason–Ludwig consistency conditions. Due to its severe ill-posedness, regression only partially recovers the correct frequency components, especially lower frequency components, and will introduce erroneous ones, particularly higher frequencies. Bilateral filtering is utilized to retain the most prominent high frequency components and suppress erroneous ones. Afterwards, a fusion in the frequency domain utilizes the restored frequency components to fill the missing double wedge region. The proposed method is evaluated in a parallel-beam study on both numerical and clinical phantoms. The root-mean-square errors of the reconstructed images decrease from 302 to 78 HU for the noise-free Shepp–Logan phantom, from 355 to 175 HU for the noisy Shepp–Logan phantom, and from 187 to 56 HU for the clinical data. The results show that our method is promising in streak reduction and intensity offset compensation in both noise-free and noisy situations.

Evaporation kinetics of surfactant solution droplets on rice (Oryza sativa) leaves.

The dynamics of evaporating sessile droplets on hydrophilic or hydrophobic surfaces is widely studied, and many models for these processes have been developed based on experimental evidence. However, few research has been explored on the evaporation of sessile droplets of surfactant or pesticide solutions on target crop leaves. Thus, in this paper the impact of surfactant concentrations on contact angle, contact diameter, droplet height, and evolution of the droplets’ evaporative volume on rice leaf surfaces have been investigated. The results indicate that the evaporation kinetics of surfactant droplets on rice leaves were influenced by both the surfactant concentrations and the hydrophobicity of rice leaf surfaces. When the surfactant concentration is lower than the surfactant CMC (critical micelle concentration), the droplet evaporation time is much longer than that of the high surfactant concentration. This is due to the longer existence time of a narrow wedge region under the lower surfactant concentration, and such narrow wedge region further restricts the droplet evaporation. Besides, our experimental data are shown to roughly collapse onto theoretical curves based on the model presented by Popov. This study could supply theoretical data on the evaporation of the adjuvant or pesticide droplets for practical applications in agriculture.

Probing the two-Higgs-doublet wedge region with charged Higgs boson decays to boosted jets

Two Higgs doublet extensions of the standard model, such as supersymmetry, predict the existence of charged Higgs bosons. We explore the reach for TeV-scale charged Higgs bosons through their associated production with top quarks, and their decay to boosted top jets and $\mu_x$ tagged boosted bottom jets, at a 14 TeV CERN Large Hadron Collider and at a 100 TeV Future Circular Collider. In particular, we show the moderate $\tan\beta$ "wedge" region of parameter space cannot be probed at the Large Hadron Collider for TeV-scale $H^\pm$ because the cross section is too small. However, a 100 TeV future proton collider can close the wedge region below 2 TeV, and search for $H^\pm$ up to 6 TeV.

A hydrodynamic suspension polishing method for ultrasmooth and low-damage surface

A novel polishing process was proposed based on the hydrodynamic phenomenon. The structure of the polishing disk was designed to form the optimal distribution of the hydrodynamic stress. Computational fluid dynamics (CFD) simulation was conducted to assist the structure design and discuss the relative mechanism. The influence of the rotating speed and suspension distance of the polishing disk on the hydrodynamic stress field were also investigated by CFD method, respectively. The microscale material removal mechanism was discussed. And then a novel polishing device was fabricated. The quality of the polishing samples were discussed. Results showed that the novel polishing disk with the wedge region, constraint boundary and flow storage tank can realize the stable hydrodynamic stress field in the workpiece region. The higher rotating speed and the shorter suspension distance both raised the magnitudes of the hydrodynamic stress. The kinetic energy of the polishing abrasive can destroy the bonding energy of the atom under the sufficient rotating speed. The stripping or moving of the raising atoms on the workpiece surface was the reason for the ultrasmooth surface. The experimental results showed that the ultrasmooth surface can be obtained by the present novel polishing process. And there were almost no machining deformation layer and micro damages.

Boundary layer transition mechanisms behind a micro-ramp

The early stage of three-dimensional laminar-to-turbulent transition behind a micro-ramp is studied in the incompressible regime using tomographic particle image velocimetry. Experiments are conducted at supercritical micro-ramp height $h$ based Reynolds number $Re_{h}=1170$. The measurement domain encompasses 6 ramp widths spanwise and 73 ramp heights streamwise. The mean flow topology reveals the underlying vortex structure of the wake flow with multiple pairs of streamwise counter-rotating vortices visualized by streamwise vorticity. The primary pair generates a vigorous upwash motion in the symmetry plane with a pronounced momentum deficit. A secondary vortex pair is induced closer to the wall. The tertiary and even further vortices maintain a streamwise orientation, but are produced progressively outwards of the secondary pair and follow a wedge-type pattern. The instantaneous flow pattern reveals that the earliest unstable mode of the wake features arc-like Kelvin–Helmholtz (K–H) vortices in the separated shear layer. Under the influence of the K–H vortices, the wake exhibits a high level of fluctuations with a pulsatile mode for the streamwise momentum deficit. The K–H vortices are lifted up due to the upwash induced by the quasi-streamwise vortex pair, while they appear to undergo pairing, distortion and finally breakdown. Immediately downstream, a streamwise interval of relatively low vortical activity separates the end of the K–H region from the formation of new hairpin vortices close to the wall. The latter vortex structures originate from the region of maximum wall shear, induced by the secondary vortex pair causing strong ejection events which transport low-speed flow upwards. The whole pattern features a cascade of hairpin vortices along a turbulent/non-turbulent interface. The wedge-shaped cascade signifies the formation of a turbulent wedge. The turbulent properties of the wake are inspected with the spatial distribution of the velocity fluctuations and turbulence production in the developing boundary layer. Inside the wedge region, the velocity fluctuations approach quasi-spanwise homogeneity, indicating the development towards a turbulent boundary layer. The wedge interface is characterized by a localized higher level of velocity fluctuations and turbulence production, associated to the deflection of the shear layer close to the wall and the onset of coherent hairpin vortices inducing localized large-scale ejections.

Structural and Functional Insights into the Unwinding Mechanism of Bacteroides sp Pif1.

Pif1 is a conserved SF1B DNA helicase involved in maintaining genome stability through unwinding double-stranded DNAs (dsDNAs), DNA/RNA hybrids, and G quadruplex (G4) structures. Here, we report the structures of the helicase domain of human Pif1 and Bacteroides sp Pif1 (BaPif1) in complex with ADP-AlF4(-) and two different single-stranded DNAs (ssDNAs). The wedge region equivalent to the β hairpin in other SF1B DNA helicases folds into an extended loop followed by an α helix. The Pif1 signature motif of BaPif1 interacts with the wedge region and a short helix in order to stabilize these ssDNA binding elements, therefore indirectly exerting its functional role. Domain 2B of BaPif1 undergoes a large conformational change upon concomitant binding of ATP and ssDNA, which is critical for Pif1's activities. BaPif1 cocrystallized with a tailed dsDNA and ADP-AlF4(-), resulting in a bound ssDNA bent nearly 90° at the ssDNA/dsDNA junction. The conformational snapshots of BaPif1 provide insights into the mechanism governing the helicase activity of Pif1.

Effect of structure and residual stresses of diamond coated cemented carbide tools on the film adhesion and developed wear mechanisms in milling

Abstract This article deals with the wear mechanisms of variously adherent nano-composite or multi-layer diamond coated tools in milling. The adhesion and residual stresses of these films on cemented-carbide inserts were characterized via inclined impact tests at diverse temperatures. The obtained results were evaluated through FEM-supported mathematical methods for estimating the maximum film residual stress and the shear failure stress (SFLS) of the coating–substrate interface. The coated inserts were used in milling AA7075 T6. The developed wear mechanisms were elucidated considering the film structure, the defined temperature-dependent SFLS and the FEM-determined stress and temperature distribution in the tool wedge region during cutting.

Central and eastern Anatolian crustal deformation rate and velocity fields derived from GPS and earthquake data

We present a new strain-rate and associated kinematic model for the eastern and central parts of Turkey. In the east, a quasi N-S compressional tectonic regime dominates the deformation field and is partitioned through the two major structural elements of the region, which are the conjugate dextral strike-slip North Anatolian Fault Zone (NAFZ) and the sinistral strike slip East Anatolian Fault Zone (EAFZ). The observed surface deformation is similar to that inferred by anisotropy studies which sampled the region of the mantle closer to the crust (i.e. the lithospheric mantle and the Moho), and is dependent on the presence or absence of a lithospheric mantle, and of the level of coupling between it and the overlaying crust. The areas of the central and eastern parts of Turkey which are deforming at elevated rates are situated above areas with strong gradients in crustal thickness. This seems to indicate that these transition zones, situated between thinner and thicker crusts, promote more deformation at the surface. The regions that reveal elevated strain-rate values are 1) the Elaziğ–Bingol segment of the EAFZ, 2) the region around the Karlıova triple-junction including the Yedisu segment and the Varto fault, 3) the section of the NAFZ that extends from the Erzincan province up to the NAFZ-Ezinepazarı fault junction, and 4) sections of the Tuz Gölü Fault Zone. Other regions like the Adana basin, a significant part of the Central Anatolian Fault Zone (CAFZ), the Aksaray and the Ankara provinces, are deforming at smaller but still considerable rates and therefore should be considered as areas well capable of producing damaging earthquakes (between M6 and 7). This study also reveals that the central part of Turkey is moving at a faster rate towards the west than the eastern part Turkey, and that the wedge region between the NAFZ and the EAFZ accounts for the majority of the counter clockwise rotation between the eastern and the central parts of Turkey. This change in movement rate and direction could be the cause of the extensional deformation and respective crustal thinning, with the resulting upwelling of warmer upper mantle observed in tomographic studies for the region between the Iskenderun bay and the CAFZ. The partitioning of deformation into an extensional regime could be the cause of the relatively low levels of strain-rate in the south-west part of the EAFZ and the northern part of the Dead Sea Fault Zone. Finally, using this new compilation of GPS data for the central-eastern part of Turkey, we obtained a new Anatolia–Eurasia rotation pole situated at 2.01°W and 31.94°N with a rotation rate of 1.053±0.015°/Ma.

Heavy Higgs bosons at 14 TeV and 100 TeV

Searching for Higgs bosons beyond the Standard Model (BSM) is one of the most important missions for hadron colliders. As a landmark of BSM physics, the MSSM Higgs sector at the LHC is expected to be tested up to the scale of the decoupling limit of O(1) TeV, except for a wedge region centered around $\tan\beta \sim 3 -10$, which has been known to be difficult to probe. In this article, we present a dedicated study testing the decoupled MSSM Higgs sector, at the LHC and a next-generation $pp$-collider, proposing to search in channels with associated Higgs productions, with the neutral and charged Higgs further decaying into $tt$ and $tb$, respectively. In the case of neutral Higgs we are able to probe for the so far uncovered wedge region via $pp\to bb H/A \to bbtt$. Additionally, we cover the the high $\tan\beta$ range with $pp\to bb H/A \to bb\tau\tau$. The combination of these searches with channels dedicated to the low $\tan\beta$ region, such as $pp\to H/A \to tt$ and $pp\to tt H/A \to tttt$ potentially covers the full $\tan\beta$ range. The search for charged Higgs has a slightly smaller sensitivity for the moderate $\tan\beta$ region, but additionally probes for the higher and lower $\tan\beta$ regions with even greater sensitivity, via $pp\to tb H^\pm \to tbtb$. While the LHC will be able to probe the whole $\tan\beta$ range for Higgs masses of O(1) TeV by combining these channels, we show that a future 100 TeV $pp$-collider has a potential to push the sensitivity reach up to $\sim \mathcal O(10)$ TeV. In order to deal with the novel kinematics of top quarks produced by heavy Higgs decays, the multivariate Boosted Decision Tree (BDT) method is applied in our collider analyses. The BDT-based tagging efficiencies of both hadronic and leptonic top-jets, and their mutual fake rates as well as the faking rates by other jets ($h$, $Z$, $W$, $b$, etc.) are also presented.

Enhanced regeneration and functional recovery after spinal root avulsion by manipulation of the proteoglycan receptor PTPσ.

Following root avulsion, spinal nerves are physically disconnected from the spinal cord. Severe motoneuron death and inefficient axon regeneration often result in devastating motor dysfunction. Newly formed axons need to extend through inhibitory scar tissue at the CNS-PNS transitional zone before entering into a pro-regenerative peripheral nerve trajectory. CSPGs are dominant suppressors in scar tissue and exert inhibition via neuronal receptors including PTPσ. Previously, a small peptide memetic of the PTPσ wedge region named ISP (Intracellular Sigma Peptide) was generated, and its capabilities to target PTPσ and relieve CSPG inhibition were validated. Here, we demonstrate that after ventral root avulsion and immediate re-implantation, modulation of PTPσ by systemic delivery of ISP remarkably enhanced regeneration. ISP treatment reduced motoneuron death, increased the number of axons regenerating across scar tissue, rebuilt healthy neuromuscular junctions and enhanced motor functional recovery. Our study shows that modulation of PTPσ is a potential therapeutic strategy for root avulsion.

Sound Radiation from a Surface Source Located at the Bottom of the Wedge Region

AbstractApplying rigorous analytical methods, formulas describing the sound radiation have been obtained for the wedge region bounded by two transverse baffles with a common edge and bottom. It has been assumed that the surface sound source is located at the bottom. The presented formulas can be used to calculate the sound pressure and power inside the wedge region. They are valid for any value of the wedge angle and represent a generalization of the formulas describing the sound radiation inside the two and three-wall corner region. Moreover, the presented formulas can be easily adapted for any case when more than one sound source is located at the bottom. To demonstrate their practical application, the distribution of the sound pressure modulus and the sound power have been analyzed in the case of a rectangular piston located at the wedge’s bottom. The influence of the transverse baffle on the sound power has been investigated. Based on the obtained formulas, the behaviour of acoustic fields inside a wedge can be predicted.