Translational Position Research Articles

Structural basis of RfaH-mediated transcription-translation coupling.

The NusG paralog RfaH mediates bacterial transcription-translation coupling in genes that contain a DNA sequence element, termed an ops site, required for pausing RNA polymerase (RNAP) and for loading RfaH onto the paused RNAP. Here, we report cryo-electron microscopy structures of transcription-translation complexes (TTCs) containing Escherichia coli RfaH. The results show that RfaH bridges RNAP and the ribosome, with the RfaH N-terminal domain interacting with RNAP and the RfaH C-terminal domain interacting with the ribosome. The results show that the distribution of translational and orientational positions of RNAP relative to the ribosome in RfaH-coupled TTCs is more restricted than in NusG-coupled TTCs because of the more restricted flexibility of the RfaH interdomain linker. The results further suggest that the structural organization of RfaH-coupled TTCs in the 'loading state', in which RNAP and RfaH are located at the ops site during formation of the TTC, is the same as the structural organization of RfaH-coupled TTCs in the 'loaded state', in which RNAP and RfaH are located at positions downstream of the ops site during function of the TTC. The results define the structural organization of RfaH-containing TTCs and set the stage for analysis of functions of RfaH during translation initiation and transcription-translation coupling.

General regulatory factors exert differential effects on nucleosome sliding activity of the ISW1a complex

BackgroundChromatin dynamics is deeply involved in processes that require access to DNA, such as transcriptional regulation. Among the factors involved in chromatin dynamics at gene regulatory regions are general regulatory factors (GRFs). These factors contribute to establishment and maintenance of nucleosome-depleted regions (NDRs). These regions are populated by nucleosomes through histone deposition and nucleosome sliding, the latter catalyzed by a number of ATP-dependent chromatin remodeling complexes, including ISW1a. It has been observed that GRFs can act as barriers against nucleosome sliding towards NDRs. However, the relative ability of the different GRFs to hinder sliding activity is currently unknown.ResultsConsidering this, we performed a comparative analysis for the main GRFs, with focus in their ability to modulate nucleosome sliding mediated by ISW1a. Among the GRFs tested in nucleosome remodeling assays, Rap1 was the only factor displaying the ability to hinder the activity of ISW1a. This effect requires location of the Rap1 cognate sequence on linker that becomes entry DNA in the nucleosome remodeling process. In addition, Rap1 was able to hinder nucleosome assembly in octamer transfer assays. Concurrently, Rap1 displayed the highest affinity for and longest dwell time from its target sequence, compared to the other GRFs tested. Consistently, through bioinformatics analyses of publicly available genome-wide data, we found that nucleosome occupancy and histone deposition in vivo are inversely correlated with the affinity of Rap1 for its target sequences in the genome.ConclusionsOur findings point to DNA binding affinity, residence time and location at particular translational positions relative to the nucleosome core as the key features of GRFs underlying their roles played in nucleosome sliding and assembly.

Organ-contour-driven auto-matching algorithm in image-guided radiotherapy.

This study aimed to demonstrate the potential clinical applicability of an organ-contour-driven auto-matching algorithm in image-guided radiotherapy. This study included eleven consecutive patients with cervical cancer who underwent radiotherapy in 23 or 25 fractions. Daily and reference magnetic resonance images were converted into mesh models. A weight-based algorithm was implemented to optimize the distance between the mesh model vertices and surface of the reference model during the positioning process. Within the cost function, weight parameters were employed to prioritize specific organs for positioning. In this study, three scenarios with different weight parameters were prepared. The optimal translation and rotation values for the cervix and uterus were determined based on the calculated translations alone or in combination with rotations, with a rotation limit of ±3°. Subsequently, the coverage probabilities of the following two planning target volumes (PTV), an isotropic 5mm and anisotropic margins derived from a previous study, were evaluated. The percentage of translations exceeding 10mm varied from 9% to 18% depending on the scenario. For small PTV sizes, more than 80% of all fractions had a coverage of 80% or higher. In contrast, for large PTV sizes, more than 90% of all fractions had a coverage of 95% or higher. The difference between the median coverage with translational positioning alone and that with both translational and rotational positioning was 1% or less. This algorithm facilitates quantitative positioning by utilizing a cost function that prioritizes organs for positioning. Consequently, consistent displacement values were algorithmically generated. This study also revealed that the impact of rotational corrections, limited to ±3°, on PTV coverage was minimal.

DNA-Histone Cross-Link Formation via Hole Trapping in Nucleosome Core Particles.

Radical cations (holes) produced in DNA by ionizing radiation and other oxidants yield DNA-protein cross-links (DPCs). Detailed studies of DPC formation in chromatin via this process are lacking. We describe here a comprehensive examination of DPC formation within nucleosome core particles (NCPs), which are the monomeric component of chromatin. DNA holes are introduced at defined sites within NCPs that are constructed from the bottom-up. DPCs form at DNA holes in yields comparable to those of alkali-labile DNA lesions that result from water trapping. DPC-forming efficiency and site preference within the NCP are dependent on translational and rotational positioning. Mass spectrometry and the use of mutant histones reveal that lysine residues in histone N-terminal tails and amino termini are responsible for the DPC formation. These studies are corroborated by computational simulation at the microsecond time scale, showing a wide range of interactions that can precede DPC formation. Three consecutive dGs, which are pervasive in the human genome, including G-quadruplex-forming sequences, are sufficient to produce DPCs that could impact gene expression.

Accuracy of Surgical Outcome Using Computer-Aided Surgical Simulation in Fronto-Orbital Advancement for Craniosynostosis: A Pilot Study.

Computer-aided surgical simulation (CASS) can be used to virtually plan ideal outcomes of craniosynostosis surgery. Our purpose was to create a workflow analyzing the accuracy of surgical outcomes relative to virtually planned fronto-orbital advancement (FOA). Patients who underwent FOA using CASS between October 1, 2017, and February 28, 2022, at our center and had postoperative computed tomography within 6 months of surgery were included. Virtual 3-dimensional (3D) models were created and coregistered using each patient's preoperative and postoperative computed tomography data. Three points on each bony segment were used to define the object in 3D space. Each planned bony segment was manipulated to match the actual postoperative outcome. The change in position of the 3D object was measured in translational (X, Y, Z) and rotational (roll, pitch, yaw) aspects to represent differences between planned and actual postoperative positions. The difference in the translational position of several bony landmarks was also recorded. Wilcoxon signed-rank tests were performed to measure significance of these differences from the ideal value of 0, which would indicate no difference between preoperative plan and postoperative outcome. Data for 63 bony segments were analyzed from 8 patients who met the inclusion criteria. Median differences between planned and actual outcomes of the segment groups ranged from -0.3 to -1.3 mm in the X plane; 1.4 to 5.6 mm in the Y plane; 0.9 to 2.7 mm in the Z plane; -1.2° to -4.5° in pitch; -0.1° to 1.0° in roll; and -2.8° to 1.0° in yaw. No significant difference from 0 was found in 21 of 24 segment region/side combinations. Translational differences of bony landmarks ranged from -2.7 to 3.6 mm. A high degree of accuracy was observed relative to the CASS plan. Virtual analysis of surgical accuracy in FOA using CASS was feasible.

Error Analysis of a New Five-Degree-of-Freedom Hybrid Robot

The error analysis of the robot has a very practical significance for improving its accuracy. Therefore, this paper conducts an error analysis for a new five-degree-of-freedom hybrid robot designed to conduct responsible surface machining. Initially, the error sources of the hybrid robot were sorted out to determine the number of error sources. Then, the error mapping model of the hybrid robot is established by the closed-loop vector method and the first-order perturbation method. Based on the mapping property of the 6th-order velocity Jacobi matrix, the compensable and non-compensable error sources affecting the posture error at the end of the hybrid robot are separated. Finally, the error analysis of the separated error sources is carried out to study the effect of single error sources and multiple error sources coupled with the posture error at the end of the robot. The results show that among the individual error sources, the dynamic and fixed platform hinge position error has the most significant effect on the end of the robot; among the integrated posture errors after coupling multiple error sources, the position of the dynamic and fixed platform hinge position error and the translational joint initial position dominate; the analysis of the different trajectories also yields that the error introduced by each error source increases gradually with the increase of the end trajectory. When designing this hybrid robot, attention should be paid to the manufacturing and installation accuracy of the dynamic and fixed platform hinge point positions and the translational joint initial position.

Wear and deformation of metal-on-polyethylene hip bearings under edge loading conditions due to variations in component positioning

Despite the clinical success of hip joint replacement, the risk of revision, particularly in younger and more active patients, still remains a concern. To identify conditions of high wear, fatigue and potential failure modes, there is need to be able to replicate a range of in vivo conditions with pre-clinical testing methods in order to predict the range of clinical wear. In particular, edge loading of metal-on-polyethylene hip replacements has the potential to have impact on both surface wear and fatigue failure. The mode of edge loading explored in this study involves separation of the centres of the femoral head and acetabular cup during a portion of the gait cycle. Such edge loading can occur due to variations in translational and/or rotational positioning of the hip replacement. In this study, the influence of translational positioning along the medial-lateral axis (medial-lateral translational mismatch) combined with rotational positioning of the acetabular cup about the anterior-posterior axis (cup inclination angle) on the occurrence and severity of edge loading, and wear and plastic deformation, was investigated for size 36 mm metal-on-polyethylene total hip replacements on a ProSim EM13 electromechanical hip joint simulator. A two phase approach was used; a short term study where the mechanics of the hip bearing were assessed under a wide range of input conditions (45° and 65° cup inclination angle and 1, 2, 3, 4 mm medial-lateral translational mismatch); followed by wear simulation for a lower number of conditions.Larger medial-lateral translational mismatch conditions led to increased levels of dynamic separation between the femoral head and acetabular cup with the largest dynamic separation (2.4 ± 0.2 mm, mean ± 95% confidence limits) measured under 4 mm translational mismatch with the 65° cup inclination angle conditions. The load at the rim at 0.5 mm of separation was also highest at this condition, as was the mean wear rate (23.0 ± 2.4 mm3 / million cycles).Dynamic separation, load at the rim and wear was consistently greater with the steeper cup inclination angle of 65° compared to 45° for all translational mismatch conditions. Translational mismatch conditions of 3 mm and 4 mm resulted in dynamic separation displacements >0.5 mm. At a 45° cup inclination angle under standard concentric conditions (zero translational mismatch) minimal wear and plastic deformation occurred at the rim of the cup, however at a 65° cup inclination edge contact at the rim was identified.Variations in rotational (cup inclination angle) and translational (medial-lateral) positioning influenced the magnitude of dynamic separation, severity of edge loading, and wear of metal – on - moderately cross-linked polyethylene hip replacements, demonstrating the importance of surgical component positioning.

Voluntary deep inspiration breath-hold with volumetric modulated arc therapy in pediatric patients with mediastinal Hodgkin lymphoma.

Background: Deep inspiration breath-hold (DIBH) has been established to decrease normal tissue radiation dose in breast cancer. Methods: Forty-nine patients had two CT scans during DIBH or free breathing. Chest-wall position, setup verification and breath-hold monitoring were performed. Cone-beam CT and a surface image system were used for verification. Results: A total of 1617 breath-holds were analyzed in 401 fractions. The mean time bit was 6.01min. The mean breaths-holds per fraction was 4.96. The median for intra-breath hold variability was 3mm. No patient stopped treatment for intolerance. Clinical target volume margins were calculated as 0.36, 0.36and 0.32 for the three translational positions. The mean saved volume was 26.3%. Conclusion: Voluntary DIBHis feasible, tolerableand easy to apply for children with Hodgkin lymphoma involving the mediastinum.

Relevance of posterior malleolar fracture fixation to ankle syndesmotic reduction, a comparative study

<p><strong>Background:</strong><strong> </strong>Appropriate distal tibiofibular syndesmotic reduction is crucial to restore ankle stability, guard against future arthrosis with worse functional outcome. Optimal technique for syndesmotic reduction has been a matter of debate. This study aimed at radiological evaluation of syndesmotic integrity following two methods of reduction (posterior malleolar fixation and trans-syndesmotic screw fixation), additionally, correlating the posterior malleolus size to the radiological results of both techniques.</p><p><strong>Methods: </strong>Syndesmotic integrity was compared after each technique as per translational and rotational fibular positions. Utilizing, preoperative and postoperative computed tomography scans of injured ankle, the fibular antero-posterior and Medio-lateral translation distances were measured. Additionally, the fibular rotation angle was calibrated. Incidence of inadequate reduction in each group was reported. Preoperative and postoperative radiological findings were compared and correlated to posterior malleolus size in relation to tibial articular distance.</p><p><strong>Results:</strong> A significant difference between both techniques was noted in term of fibular rotation. In patients with PM ˂ 10% of tibial articular surface, a significant difference was obvious in postoperative AP-translational and rotational findings between both techniques. Overall malreduction incidence rate of 68.9% was reported in this study, with 84.7% rate in patients managed with SS-fixation, whilst 51.2% rate in those managed via PM-fixation.</p><p><strong>Conclusions:</strong><strong> </strong>Posterior malleolar fixation could limit syndesmotic malreduction risk whatsoever it’s size. Approaching CT reference values for syndesmotic reduction might benefit preoperative planning and detect intraoperative malreduction. Further future clinical studies correlating these findings to clinical outcome would be more helpful.</p>

Scale Factor Estimation for Quadrotor Monocular-Vision Positioning Algorithms.

Unmanned aerial vehicle (UAV) autonomous navigation requires access to translational and rotational positions and velocities. Since there is no single sensor to measure all UAV states, it is necessary to fuse information from multiple sensors. This paper proposes a deterministic estimator to reconstruct the scale factor of the position determined by a simultaneous localization and mapping (SLAM) algorithm onboard a quadrotor UAV. The position scale factor is unknown when the SLAM algorithm relies on the information from a monocular camera. Only onboard sensor measurements can feed the estimator; thus, a deterministic observer is designed to rebuild the quadrotor translational velocity. The estimator and the observer are designed following the immersion and invariance method and use inertial and visual measurements. Lyapunov’s arguments prove the asymptotic convergence of observer and estimator errors to zero. The proposed estimator’s and observer’s performance is validated through numerical simulations using a physics-based simulator.

Visual and Control Augmentation Techniques for Pilot Assistance During Helicopter Shipboard Recovery

Shipboard launch and recovery of helicopters continue to pose operational challenges even to experienced pilots. The present research seeks to develop novel visual and control augmentation techniques and determine their impact on human factors for shipboard recovery operations. The paper first outlines the development and integration of a helicopter–ship dynamic interface model into a wide field of view, fixed-base rotorcraft simulation environment. The paper then describes the development of novel visual and control augmentation techniques for pilot assistance during shipboard recovery. Visual augmentation includes two-dimensional primary flight information and three-dimensional conformal shipboard landing symbology presented on a low-cost, off-the-shelf, see-through head-mounted display system to facilitate "eyes-out" piloting. Control augmentation includes robust nonlinear control laws producing translational rate command position hold, and acceleration command velocity hold response types with good predicted handling qualities. Finally, the paper reports experimental results of simulated visual shipboard approaches conducted with four experimental test pilots for low- and high-intensity ship motions. The results indicate improved piloting performance, mitigation of pilot-induced oscillations, lower workload, improved handling, and improved perceived safety for fleet pilots for the proposed visual and control augmentation techniques.

An Analytic Solution to the Inverse Dynamics of an Energy Harvesting Tethered Kite

Abstract This paper solves the inverse dynamics of a tethered kite analytically. Specifically, the paper presents a procedure for determining the angle of attack, induced roll angle, and tether tension magnitude needed to achieve a desired combination of translational kite position, velocity, and acceleration. The focus of the paper is on energy harvesting kites. However, the underlying approach is applicable to other kite systems, such as kites for propulsion (e.g., SkySails, Hamburg, Germany). Solving inverse kite dynamics analytically is valuable for trajectory optimization, online state estimation, and the analysis of fundamental limitations on kite maneuvers. Previous work in the literature presents several models of kite dynamics, with varying degrees of fidelity and complexity. However, the nonlinearity of these models often makes them difficult to use for optimization, estimation, and control. The paper shows that, under reasonable assumptions, inverse kite dynamics can be solved in terms of the roots of a fourth-order polynomial function of angle of attack. This function has a geometric interpretation, providing insight into the multiplicity of resulting solutions. Moreover, for special cases including a kite with noncambered wings, these solutions can be computed analytically. A simulation validates the success of the proposed approach in computing inverse kite dynamics for a cross-current trajectory.

Translational Speed Control and Positioning of Precision Agricultural Robot

All kinds of agricultural labor may lead to farmers’ fatigue or disease. To help accomplish these tasks, robotics is used as a possibility to minimize the above inconvenience. With this in mind, the Military University of New Granada designed and built a robot called CERES, which is responsible for removing weeds, spraying, etc. In order for CERES to move in the crop along the required path, it must be ensured that the robot moves at a specific translational speed and direction, which is ensured by using the controller. This paper introduces the use of SSV (steady state value) criterion and the control signal allowed by the robot hardware, designs and implements a PID controller for tracking the linear speed and direction and ensuring that the stability time is met when the error tends to zero.

Development of a Monte Carlo based robustness calculation and evaluation tool.

BackgroundEvaluating plan robustness is a key step in radiotherapy.PurposeTo develop a flexible Monte Carlo (MC)‐based robustness calculation and evaluation tool to assess and quantify dosimetric robustness of intensity‐modulated radiotherapy (IMRT) treatment plans by exploring the impact of systematic and random uncertainties resulting from patient setup, patient anatomy changes, and mechanical limitations of machine components.MethodsThe robustness tool consists of two parts: the first part includes automated MC dose calculation of multiple user‐defined uncertainty scenarios to populate a robustness space. An uncertainty scenario is defined by a certain combination of uncertainties in patient setup, rigid intrafraction motion and in mechanical steering of the following machine components: angles of gantry, collimator, table‐yaw, table‐pitch, table‐roll, translational positions of jaws, multileaf‐collimator (MLC) banks, and single MLC leaves. The Swiss Monte Carlo Plan (SMCP) is integrated in this tool to serve as the backbone for the MC dose calculations incorporating the uncertainties. The calculated dose distributions serve as input for the second part of the tool, handling the quantitative evaluation of the dosimetric impact of the uncertainties. A graphical user interface (GUI) is developed to simultaneously evaluate the uncertainty scenarios according to user‐specified conditions based on dose‐volume histogram (DVH) parameters, fast and exact gamma analysis, and dose differences. Additionally, a robustness index (RI) is introduced with the aim to simultaneously evaluate and condense dosimetric robustness against multiple uncertainties into one number. The RI is defined as the ratio of scenarios passing the conditions on the dose distributions. Weighting of the scenarios in the robustness space is possible to consider their likelihood of occurrence. The robustness tool is applied on IMRT, a volumetric modulated arc therapy (VMAT), a dynamic trajectory radiotherapy (DTRT), and a dynamic mixed beam radiotherapy (DYMBER) plan for a brain case to evaluate the robustness to uncertainties of gantry‐, table‐, collimator angle, MLC, and intrafraction motion. Additionally, the robustness of the IMRT, VMAT, and DTRT plan against patient setup uncertainties are compared. The robustness tool is validated by Delta4 measurements for scenarios including all uncertainty types available.ResultsThe robustness tool performs simultaneous calculation of uncertainty scenarios, and the GUI enables their fast evaluation. For all evaluated plans and uncertainties, the planning target volume (PTV) margin prevented major clinical target volume (CTV) coverage deterioration (maximum observed standard deviation of D98%CTV was 1.3 Gy). OARs close to the PTV experienced larger dosimetric deviations (maximum observed standard deviation of D2%chiasma was 14.5 Gy). Robustness comparison by RI evaluation against patient setup uncertainties revealed better dosimetric robustness of the VMAT and DTRT plans as compared to the IMRT plan. Delta4 validation measurements agreed with calculations by >96% gamma‐passing rate (3% global/2 mm).ConclusionsThe robustness tool was successfully implemented. Calculation and evaluation of uncertainty scenarios with the robustness tool were demonstrated on a brain case. Effects of patient and machine‐specific uncertainties and the combination thereof on the dose distribution are evaluated in a user‐friendly GUI to quantitatively assess and compare treatment plans and their robustness.

Functional characterization of 5\u2032 UTR cis-acting sequence elements that modulate translational efficiency in Plasmodium falciparum and humans

BackgroundThe eukaryotic parasite Plasmodium falciparum causes millions of malarial infections annually while drug resistance to common anti-malarials is further confounding eradication efforts. Translation is an attractive therapeutic target that will benefit from a deeper mechanistic understanding. As the rate limiting step of translation, initiation is a primary driver of translational efficiency. It is a complex process regulated by both cis and trans acting factors, providing numerous potential targets. Relative to model organisms and humans, P. falciparum mRNAs feature unusual 5′ untranslated regions suggesting cis-acting sequence complexity in this parasite may act to tune levels of protein synthesis through their effects on translational efficiency.MethodsHere, in vitro translation is deployed to compare the role of cis-acting regulatory sequences in P. falciparum and humans. Using parasite mRNAs with high or low translational efficiency, the presence, position, and termination status of upstream “AUG”s, in addition to the base composition of the 5′ untranslated regions, were characterized.ResultsThe density of upstream “AUG”s differed significantly among the most and least efficiently translated genes in P. falciparum, as did the average “GC” content of the 5′ untranslated regions. Using exemplars from highly translated and poorly translated mRNAs, multiple putative upstream elements were interrogated for impact on translational efficiency. Upstream “AUG”s were found to repress translation to varying degrees, depending on their position and context, while combinations of upstream “AUG”s had non-additive effects. The base composition of the 5′ untranslated regions also impacted translation, but to a lesser degree. Surprisingly, the effects of cis-acting sequences were remarkably conserved between P. falciparum and humans.ConclusionsWhile translational regulation is inherently complex, this work contributes toward a more comprehensive understanding of parasite and human translational regulation by examining the impact of discrete cis-acting features, acting alone or in context.

Prescribed flexible orientation workspace and performance comparison of non-redundant 3-DOF planar parallel mechanisms

The functionality of a workspace is one of the most important considerations in planar parallel manipulators (PPMs) design. Dexterous workspace (DW) is the subset of the reachable workspace (RW) and it means that full rotational dexterity is preserved in every translational position in space. However, DW is impractical as PPMs cannot rotate a full 360° because of interference. This paper proposes a workspace called prescribed flexible orientation workspace (PFOW) that characterizes the orientation capability of PPMs. To optimize and compare 3 degree-of-freedom (3-DOF) PPMs, a normalized and unified performance characteristic index is built based on indices including PFOW, condition number, velocity, payload, stiffness, and transmission indices which plays a guiding role in the optimization process. The best configuration is obtained through graphical performance comparison. In general, this work presents the analysis of rotational dexterity of PPMs and provides a guidance for optimization and selection.

Self-Bearing Machine Modeling Reflecting Rotor Position Induced Non-Linearity Based on 7-D Lookup Table

The rotor of self-bearing machines can be in an off-centered position as they lack of physical bearings. The air-gap length and effective area with respect to each phase become nonuniform, which results in inductance and back EMF non-linearities. Evaluation of self-bearing machines performance in time domain is inaccurate without a model that includes non-linear inductance and back EMF constants. To reflect non-linearities, finite element analysis (FEA) is often used. However, FEA requires large computational power to run in time-domain simulation. In this article, a 7-D lookup table (7-D LUT) model of inductance and back EMF constants, suspension forces, and torque is proposed for time-domain simulation, including non-linearity from the rotor translational and rotational displacement. Pre-evaluated FEA results are post-processed to construct the 7-D LUT model to enable fast and accurate time-domain simulation reflecting non-linearities from the input of rotary position (slotting effect), translational position in horizontal and vertical directions (unbalanced air-gap field effect), and magnetic saturation effect. A combined winding self-bearing machine is evaluated using the proposed method and verified with FEA and experimental results.

Uncertainty in the positioning of patients receiving treatment for brain metastases and wearing surgical mask underneath thermoplastic mask during COVID-19 crisis.

Thermoplastic masks, used along with surgical masks, enable immobilization methods to reduce the risk of infection in patients undergoing intracranial stereotactic radiosurgery and stereotactic radiotherapy (SRS/SRT) during the COVID‐19 crisis. The purpose of this study was to investigate the feasibility of thermoplastic mask immobilization with a surgical mask using an ExacTrac system. Twelve patients each with brain metastases were immobilized using a thermoplastic mask and a surgical mask and only a thermoplastic mask. Two x‐ray images were acquired to correct (XC) and verify (XV) the patient’s position at a couch angle of 0°. Subsequently, the XC and XV images were acquired at each planned couch angle for non‐coplanar beams. When the position errors were detected after couch rotation for non‐coplanar beams, the errors were corrected at each planned couch angle until a clinically acceptable tolerance was attained. The position errors in the translational and rotational directions (vertical, lateral, longitudinal, pitch, roll, and yaw) were retrospectively investigated using data from the ExacTrac system database. A standard deviation of XC translational and rotational position errors with and without a surgical mask in the lateral (1.52 vs 2.07 mm), longitudinal (1.59 vs 1.87 mm), vertical (1.00 vs 1.73 mm), pitch (0.99 vs 0.79°), roll (1.24 vs 0.68°), and yaw (1.58 vs 0.90°) directions were observed at a couch angle of 0°. Most of patient positioning errors were less than 1.0 mm or 1.0° after the couch was rotated to the planned angle for non‐coplanar beams. The overall absolute values of the translational and rotational XV position errors with and without the surgical mask were less than 0.5 mm and 0.5°, respectively. This study showed that a thermoplastic mask with a surgical mask is a feasible immobilization technique for brain SRS/SRT patients using the ExacTrac system.

The role of delta and theta oscillations during ego-motion in healthy adult volunteers

The successful cortical processing of multisensory input typically requires the integration of data represented in different reference systems to perform many fundamental tasks, such as bipedal locomotion. Animal studies have provided insights into the integration processes performed by the neocortex and have identified region specific tuning curves for different reference frames during ego-motion. Yet, there remains almost no data on this topic in humans.In this study, an experiment originally performed in animal research with the aim to identify brain regions modulated by the position of the head and eyes relative to a translational ego-motion was adapted for humans. Subjects sitting on a motion platform were accelerated along a translational pathway with either eyes and head aligned or a 20° yaw-plane offset relative to the motion direction while EEG was recorded.Using a distributed source localization approach, it was found that activity in area PFm, a part of Brodmann area 40, was modulated by the congruency of translational motion direction, eye, and head position. In addition, an asymmetry between the hemispheres in the opercular-insular region was observed during the cortical processing of the vestibular input. A frequency specific analysis revealed that low-frequency oscillations in the delta- and theta-band are modulated by vestibular stimulation. Source-localization estimated that the observed low-frequency oscillations are generated by vestibular core-regions, such as the parieto-opercular region and frontal areas like the mid-orbital gyrus and the medial frontal gyrus.

Nonreciprocal and Conditional Cooperativity Directs the Pioneer Activity of Pluripotency Transcription Factors

Cooperative binding of transcription factors (TFs) to chromatin orchestrates gene expression programming and cell fate specification. However, the biophysical principles of TF cooperativity remain incompletely understood. Here we use single-molecule fluorescence microscopy to study the partnership between Sox2 and Oct4, two core members of the pluripotency gene regulatory network. We find that the ability of Sox2 to target DNA inside nucleosomes is strongly affected by the translational and rotational positioning of its binding motif.