Standard Experimental Setup Research Articles

High-Frequency 1H NMR Chemical Shifts of SnII and PbII Hydrides Induced by Relativistic Effects: Quest for PbII Hydrides.

The role of relativistic effects on 1H NMR chemical shifts of SnII and PbII hydrides is investigated by using fully relativistic DFT calculations. The stability of possible PbII hydride isomers is studied together with their 1H NMR chemical shifts, which are predicted in the high-frequency region, up to 90 ppm. These 1H signals are dictated by sizable relativistic contributions due to spin-orbit coupling at the heavy atom and can be as large as 80 ppm for a hydrogen atom bound to PbII. Such high-frequency 1H NMR chemical shifts of PbII hydride resonances cannot be detected in the 1H NMR spectra with standard experimental setup. Extended 1H NMR spectral ranges are thus suggested for studies of PbII compounds. Modulation of spin-orbit relativistic contribution to 1H NMR chemical shift is found to be important also in the experimentally known SnII hydrides. Because the 1H NMR chemical shifts were found to be rather sensitive to the changes in the coordination sphere of the central metal in both SnII and PbII hydrides, their application for structural investigation is suggested.

Laboratory experiment for the study of friction forces using rotating apparatus

The standard experimental set-up enabling observation of rotational motion of a bar around its centre of mass, which is set into motion due to the external torque generated by the small weight, was extended with an optical gate and position sensor and connected to a computer with software, which made it possible to display measured values of bar half-rotations during accelerated and decelerated motion as well as to process the data immediately. The detailed analysis of experimental data obtained for decelerated rotational motion due to frictional torque only (without small weight) showed that, besides the constant term due to dry friction at an axle, the expression for friction forces in the system has to include terms depending on the first and/or second power of angular speed, which is evidence that viscous forces influence the motion of a bar. The frictional torque due to viscous forces can be evaluated as the difference between the effective frictional torque acting on the system and the frictional torque due to dry friction at an axle. The data obtained in the experiment in which the bar performed damped oscillatory motion provided the values of effective frictional torque and the moment of inertia of rotating bodies. The frictional torque due to dry friction can be obtained as a minimum torque (calculated using minimum mass of weight) needed to start rotational motion. The last two proposed experiments can be included in undergraduate laboratory practicals.

Model Based Determination of Gait Parameters Using IMU Sensor Data

The paper deals with the determination of gait parameters using inertial measurement units (IMU). An IMU sensor incorporates three microelectromechanical sensors - triple-axis gyroscope, accelerometer and magnetometer. A standard experimental setup for the observation of the locomotion system using seven Xsens MTw sensors was developed. They are applied to the lower limbs and the pelvis of the subject. The synchronization of data from all sensor components (gyroscope, accelerometer and magnetometer) as well as the onboard estimation of the orientation is provided by the Xsens and Adwinda hard-and software. The strapped down data are received with a rate of 60 Hz. The output data of a single IMU sensor allow motion analysis of the sensor unit itself as well as the motion of the limb where the sensor is mounted to. Stable and reliable algorithms processing the gait data and calculating gait features of a single sensor are developed and evaluated. These algorithms are based on precise determination of each gait cycle. In the middle of stance phase the foot is not moving. It stands on the floor and, following, the initial conditions for the calculation of foot velocities and distances by integration are predetermined. Various features of the gait cycle as well as e.g. dependencies in between features or on the gait velocities are investigated. The application of seven sensors to the limbs of the locomotion system provides measurements of their 3D motion observed in an inertial coordinate system. The limbs are parts of skeleton and interconnected by joints. Introducing a skeleton model, the quality of measurements is evaluated and improved. Joint angles, symmetry ratios and other gait parameters are determined. These results can be used for analysis of the gait of any subject as well as of any cohort.

Single Pass Albumin Dialysis-A Dose-Finding Study to Define Optimal Albumin Concentration and Dialysate Flow.

Several artificial liver support concepts have been evaluated both in vitro and clinically. Single pass albumin dialysis (SPAD) has shown to be one of the most simple approaches for removing albumin-bound toxins and water-soluble substances. Being faced with acute liver failure (ALF) in everyday practice encouraged our attempt to define the optimal conditions for SPAD more precisely in a standardized experimental setup. Albumin concentration was adjusted to either 1%, 2%, 3%, or 4%, while the flow rate of the dialysate was kept constant at a speed of 700 mL/h. The flow rate of the dialysate was altered between 350, 500, 700, and 1000 mL/h, whereas the albumin concentration was continuously kept at 3%. This study revealed that the detoxification of albumin-bound substances could be improved by increasing the concentration of albumin in the dialysate with an optimum at 3%. A further increase of the albumin concentration to 4% did not lead to a significant increase in detoxification. Furthermore, we observed a gradual increase of the detoxification efficiency for albumin-bound substances, from 350 mL/h to 700 mL/h (for bilirubin) or 1000 mL/h (for bile acids) of dialysate flow. Water-soluble toxins (ammonia, creatinine, urea, uric acid) were removed almost completely, regardless of albumin concentration or flow rate. In conclusion, this study confirmed that SPAD is effective in eliminating albumin-bound as well as water-soluble toxins using a simulation of ALF. Furthermore, this project was successful in evaluating the most effective combination of albumin concentration (3%) and dialysate flow (700 mL/h-1000 mL/h) in SPAD for the first time.

Track-a-Forager: a program for the automated analysis of RFID tracking data to reconstruct foraging behaviour

Behavioural studies make increasingly use of the passive radio-frequency identification (RFID) technology to monitor the foraging behaviour and activity patterns of individual animals over extended periods of time. Central place foragers, such as social insects, birds and many rodents have proved particularly well suited for this technology. As yet, however, there is no standardized methodology to filter and postprocess the data resulting from RFID scanners. Here we present a new user-friendly, publically available Java program named “Track-a-Forager” to analyse and rigorously filter RFID animal tracking data. The program is particularly suited and has special features to analyse social insect behaviour, but it is generic enough to analyse data obtained from any species. The implemented filtering algorithm consists of several well-defined steps to cluster multiple temporally clustered RFID scans of the same individual, determine events of leaving and entering the nest and/or feeder and reconstruct foraging trips for each individual. Track-a-Forager analyses RFID data independent of the used scanner system for eight different types of standard experimental setups that are common in foraging behaviour research. These setups differ with respect to whether or not foraging at an artificial feeder is monitored and the specific placement of the RFID scanners at the nest or feeder. As a real-life example, we show how Track-a-Forager enables one to reconstruct 75 % more foraging trips compared to if one were to use the raw data.

Large-scale 3D modeling of projectile impact damage in brittle plates

The damage and failure of brittle plates subjected to projectile impact is investigated through large-scale three-dimensional simulation using the DG/CZM approach introduced by Radovitzky et al. [Comput. Methods Appl. Mech. Eng. 2011; 200(1–4), 326–344]. Two standard experimental setups are considered: first, we simulate edge-on impact experiments on Al2O3 tiles by Strassburger and Senf [Technical Report ARL-CR-214, Army Research Laboratory, 1995]. Qualitative and quantitative validation of the simulation results is pursued by direct comparison of simulations with experiments at different loading rates and good agreement is obtained. In the second example considered, we investigate the fracture patterns in normal impact of spheres on thin, unconfined ceramic plates over a wide range of loading rates. For both the edge-on and normal impact configurations, the full field description provided by the simulations is used to interpret the mechanisms underlying the crack propagation patterns and their strong dependence on loading rate.

Demonstrating genuine multipartite entanglement and nonseparability without shared reference frames

Multipartite nonlocality is of great fundamental interest and constitutes a useful resource for many quantum information protocols. However, demonstrating it in practice, by violating a Bell inequality, can be difficult. In particular, standard experimental setups require the alignment of distant parties' reference frames, which can be challenging or impossible in practice. In this work we study the violation of certain Bell inequalities, namely the Mermin, Mermin-Klyshko and Svetlichny inequalities, without shared reference frames, when parties share a Greenberger-Horne-Zeilinger (GHZ) state. Furthermore, we analyse how these violations demonstrate genuine multipartite features of entanglement and nonlocality. For 3, 4 and 5 parties, we show that it is possible to violate these inequalities with high probability, when the parties choose their measurements from the three Pauli operators, defined only with respect to their local frames. Moreover, the probability of violation, and the amount of violation, are increased when each party chooses their measurements from the four operators describing the vertices of a tetrahedron. We also consider how many randomly chosen measurement directions are needed to violate the Bell inequalities with high probability. We see that the obtained levels of violation are sufficient to also demonstrate genuine multipartite entanglement and nonseparability. Finally, we show analytically that choosing from two measurement settings per party is sufficient to demonstrate the maximum degree of genuine multipartite entanglement and nonseparability with certainty when the parties' reference frames are aligned in one direction so that they differ only in rotations around one axis.

Microwave-controlled efficient Raman sub-harmonic generation.

We propose a novel scheme for efficient Raman sub-harmonic generation in a system of inhomogeneously broadened atomic vapor with atoms in a closed three-level Λ-configuration. The key feature underlying Raman sub-harmonics generation is microwave-induced hyperfine coherence between the two lower level metastable states. We show explicitly how the amplitude and phase of the microwave field generate controllable spectral amplitudes of Raman sub-harmonics. Our scheme is viable in currently available atomic vapor cells thereby opening the way for efficient sub-harmonic generation in standard experimental setups.

GC-MS based targeted metabolic profiling identifies changes in the wheat metabolome following deoxynivalenol treatment.

Fusarium graminearum and related species commonly infest grains causing the devastating plant disease Fusarium head blight (FHB) and the formation of trichothecene mycotoxins. The most relevant toxin is deoxynivalenol (DON), which acts as a virulence factor of the pathogen. FHB is difficult to control and resistance to this disease is a polygenic trait, mainly mediated by the quantitative trait loci (QTL) Fhb1 and Qfhs.ifa-5A. In this study we established a targeted GC–MS based metabolomics workflow comprising a standardized experimental setup for growth, treatment and sampling of wheat ears and subsequent GC–MS analysis followed by data processing and evaluation of QC measures using tailored statistical and bioinformatics tools. This workflow was applied to wheat samples of six genotypes with varying levels of Fusarium resistance, treated with either DON or water, and harvested 0, 12, 24, 48 and 96 h after treatment. The results suggest that the primary carbohydrate metabolism and transport, the citric acid cycle and the primary nitrogen metabolism of wheat are clearly affected by DON treatment. Most importantly significantly elevated levels of amino acids and derived amines were observed. In particular, the concentrations of the three aromatic amino acids phenylalanine, tyrosine, and tryptophan increased. No clear QTL specific difference in the response could be observed except a generally faster increase in shikimate pathway intermediates in genotypes containing Fhb1. The overall workflow proved to be feasible and facilitated to obtain a more comprehensive picture on the effect of DON on the central metabolism of wheat.Electronic supplementary materialThe online version of this article (doi:10.1007/s11306-014-0731-1) contains supplementary material, which is available to authorized users.

Sensitive and specific in situ hybridization for early drug discovery.

High-throughput analyses of gene expression such as microarrays and RNA-sequencing are widely used in early drug discovery to identify disease-associated genes. To further characterize the expression of selected genes, in situ hybridization (ISH) using RNA probes (riboprobes) is a powerful tool to localize mRNA expression at the cellular level in normal and diseased tissues, especially for novel drug targets, where research tools like specific antibodies are often lacking.We describe a sensitive ISH protocol using radiolabelled riboprobes suitable for both paraffin-embedded and cryo-preserved tissue. The riboprobes are generated by in vitro transcription using PCR products as templates, which is less time consuming compared to traditional transcription from linearized plasmids, and offers a relatively simple way to generate several probes per gene, e.g., for splice variant analyses. To ensure reliable ISH results, we have incorporated a number of specificity controls in our standard experimental setup. We design antisense probes to cover two non-overlapping parts of the gene of interest, and use the corresponding sense probes as controls for unspecific binding. Probes are furthermore tested on sections of paraffin-embedded or cryo-preserved positive and negative control cells with known gene expression. Our protocol thus provides a method for sensitive and specific ISH, which is suitable for target validation and characterization in early drug discovery.

Microwave reflection study of ultra-high mobility GaAs/AlGaAs 2D-electron system at large filling factors

ABSTRACTThe microwave-induced magnetoresistance oscillations are exhibited by the GaAs/AlGaAs two dimensional electron system (2DES) under microwave and terahertz photo-excitation at liquid helium temperatures. Such oscillations are presently understood in terms of various theories. In order to identify the relative physical contributions, we have concurrently examined magnetotransport and microwave reflection from the 2DES. For the reflection measurements, a sensitive microwave detector was assimilated into the standard experimental setup. Here, we correlate changes in reflection with the concurrent transport response of the photo-excited 2DES.

Makefiles for Moses

Abstract Building MT systems with the Moses toolkit is a task so complex that it is rarely done manually. Over the years, several frameworks for building, running, and evaluating Moses systems have been developed, most notably the Experiment Management System (EMS). While EMS works well for standard experimental set-ups and offers good web integration, designing new experimental set-ups within EMS is not trivial, especially when the new processing pipeline differs considerably from the kind EMS is intended for. In this paper, I present M4M (Makefiles for Moses), a framework for building and evaluating Moses MT systems with the GNU Make utility. I illustrate the capabilities by a simple set-up that builds and compares two different systems with common resources. This set-up requires little more than putting training, tuning and evaluation data into the right directories and running Make.1 The purpose of this paper is twofold: to guide first-time users of Moses through the process of building baseline MT systems, and to discuss some lesser-known features of the Make utility that enable the MT practitioner to set up complex experimental scenarios efficiently. M4M is part of the Moses distribution.

Comparison of the primary stability of different tibial baseplate concepts to retain both cruciate ligaments during total knee arthroplasty

BackgroundA novel tibial baseplate design (Transversal Support Tibial Plateau) as a new treatment concept for bi-cruciate retaining total knee arthroplasty is evaluated for mechanical stability and compared to other tibial baseplate designs.This concept should provide better primary stability and thus, less subsidence, than implantation of two separate unicondylar tibial baseplates. MethodsDifferent baseplates were implanted into synthetic bone specimens (Sawbones® Pacific Research Laboratories, Inc., Washington, USA), all uncemented. Using a standardized experimental setup, subsidence was achieved, enabling comparison of the models regarding primary stability. FindingsOverall implant subsidence was significantly increased for the two separate unicondylar tibial baseplates versus the new Transversal Support Tibial Plateau concept, which showed comparable levels to a conventional tibial baseplate. Reduced subsidence results in better primary stability. InterpretationLinking of two separate baseplates appears to provide increased primary stability in terms of bony fixation, comparable to that of a conventional single tibial baseplate.

Optical analysis of spatially periodic patterns in nematic liquid crystals: Diffraction and shadowgraphy

Optical methods are most convenient for analyzing spatially periodic patterns with wave vector q in a thin layer of a nematic liquid crystal. In the standard experimental setup a beam of parallel light with a "short" wavelength λ<<2π/q passes the nematic layer. Recording the transmitted light the patterns are either directly visualized by shadowgraphy or characterized more indirectly by the diffraction fringes due to the optical-grating effects of the pattern. In this work we present a systematic short-wavelength analysis of these methods for the commonly used planar orientation of the optical axis of liquid crystal at the confining surfaces. Our approach covers general three-dimensional experimental geometries with respect to the relative orientation of q and of the wave vector k of the incident light. In particular, we emphasize the importance of phase-grating effects, which are not accessible in a pure geometric optics approach. Finally, as a by-product we present also an optical analysis of convection rolls in Rayleigh-Bénard convection, where the refraction index of the fluid is isotropic in contrast to its uniaxial symmetry in nematic liquid crystals. Our analysis is in excellent agreement with an earlier physical optics approach by Trainoff and Cannell [Phys. Fluids 14, 1340 (2002)], which is restricted to a two-dimensional geometry and technically much more demanding.

The TUM Gait from Audio, Image and Depth (GAID) database: Multimodal recognition of subjects and traits

Recognizing people by the way they walk-also known as gait recognition-has been studied extensively in the recent past. Recent gait recognition methods solely focus on data extracted from an RGB video stream. With this work, we provide a means for multimodal gait recognition, by introducing the freely available TUM Gait from Audio, Image and Depth (GAID) database. This database simultaneously contains RGB video, depth and audio. With 305 people in three variations, it is one of the largest to-date. To further investigate challenges of time variation, a subset of 32 people is recorded a second time. We define standardized experimental setups for both person identification and for the assessment of the soft biometrics age, gender, height, and shoe type. For all defined experiments, we present several baseline results on all available modalities. These effectively demonstrate multimodal fusion being beneficial to gait recognition.

Characterization of anticipatory behaviour in domesticated horses (Equus caballus)

In animal welfare science there is a strong need for objective parameters for the assessment of animal welfare. Anticipatory behaviour is a potential indicator of welfare since it reflects reward-sensitivity which is in its turn related to previous experiences of animals: negative experiences are positively correlated with reward-sensitivity and vice versa. In rats and several other species, anticipatory behaviour is reported to be characterized by an increase in activity. As a first step for future use of anticipatory behaviour as a welfare indicator in horses, the aim of this research was to characterize the equine anticipatory response to a reward. Both behaviours and parameters on autonomic heart rate (HR) and heart rate variability (HRV) have been measured in order to provide a full characterization of the anticipatory response. Anticipatory behaviours, HR and HRV of 13 horses were recorded in two separate experiments: 1. Before arrival of concentrate feeding during their normal daily routine and 2. During a standardized experimental set-up in which anticipation was evoked by means of a conditioning paradigm. Thus, in the first experiment the already existing anticipatory behaviour was investigated, whereas in the second experiment a new association between an unconditioned and conditioned stimulus was induced. An extensive ethogram was used to score all behaviours, afterwards behavioural elements were grouped in four different categories i.e. maintenance behaviour, standing, locomotion, and arousal and investigation. It was apparent that equine anticipatory response could be characterized as an increase in activity together with an increase in heart rate. In addition, both frequency and duration of standing, locomotion and arousal and investigation were significantly increased, while a significant decrease in time spent on maintenance behaviour was shown during anticipation. The increase in activity during anticipation was not influenced by individual differences, i.e. expression of specific anticipatory behaviours in some horses. Since the main characteristic of anticipation is an increase in activity, reflected by the number of behavioural transitions, results of this study are promising for future research on anticipatory behaviour as an equine welfare indicator.

Unified measurement system with suction control for measuring hysteresis in soil‐gas transport parameters

A unified measurement system with suction control (UMS_SC) was developed for measuring soil water characteristics curves (SWCC) and gas transport parameters under alternating drying and wetting cycles. The new system consists of a diffusion chamber, sample ring, porous plate, tensiometer, moisture sensor, oxygen electrodes, and air pressure gauges. The SWCC and gas transport parameters [gas diffusion coefficient (Dp) and air permeability (ka)] for two different porous materials, Toyoura sand and granulated slag, were simultaneously measured under drying and wetting cycles. The SWCC and gas transport parameters measured by UMS_SC were consistent with recent models and independently measured data on exactly the same materials using standard experimental setups from literature. For an applied water suction head of less than 50 cm and corresponding water saturation of around 0.3–0.5, the UMS_SC data documented hysteretic (nonsingular) behavior in both measured Dp and ka under repeated drying and wetting cycles. The hysteretic behavior was insignificant for water and air contents but large for both gas transport parameters when applying suction, and hysteretic effects were larger for air permeability than for gas diffusivity. Additionally, hysteresis in the percolation threshold (soil‐air content where gas transport ceases due to interconnected water‐filled pores) for both gas diffusion and air permeability was insignificant for both materials. These findings should be taken into account when developing models for diffusive and convective gas transport and their parameters in variably saturated porous media.

Permeability of Rapid Prototyped Artificial Bone Scaffold Structures

Fluid flow through a bone scaffold structure is an important factor in its ability to build up a living tissue. Permeability is often used as a measure of a structure’s ability to allow for flow of nutrients and waste products related to the growth of new tissue. These structures also need to meet conflicting mechanical strength requirements to allow for load bearing. In this work, the effect of different bone structure morphologies on permeability were examined both numerically and experimentally. Cubic and hexagonal based three dimensional scaffold structures were produced via stereolithography and 3D printing techniques. In particular, porosity percentage, pore size, and pore geometry were examined. Porosity content was varied from 30% to 70% and pore size from 0.34 mm to 3 mm. An adapted Kozeny-Carmen numerical method was applied for calculation of permeability through these structures and an experimental validation of these results was performed via a standard permeability experimental testing set-up. From the results it was determined that increased permeability was provided with the cubic rather than hexagonal structure as well as by utilizing the larger pore size and higher levels of porosity. Stereolithography was found to be the better processing technique, not only for improved micrometer scale dimensional accuracy reasons, but also due to the increase wettability found on the produced surfaces. The appropriate model constants determined in this work will allow for analysis of new alternate structure designs on the permeability of rapid prototyped synthetic bone structures.

2-ps Hard X-Ray Streak Camera Measurements at Sector 7 Beamline of the Advanced Photon Source

A hard X-ray streak camera capable of 2-ps time resolution is in operation at the Sector 7 beamline of the Advanced Photon Source. It is used for laser-pump, X-ray probe experiments using the Ti:Sapphire femtosecond laser system installed on the beamline. This streak camera, combined with standardized and prealigned experimental setups, can perform time-resolved liquid-phase absorption spectroscopy, reflectivity, and diffraction experiments.

Permeability of Rapid Prototyped Artificial Bone Scaffold Structures

Fluid flow through a bone scaffold structure is an important factor in its ability to build up a living tissue. Permeability is often used as a measure of a structure’s ability to allow for flow of nutrients and waste products related to the growth of new tissue. These structures also need to meet conflicting mechanical strength requirements to allow for load bearing. In this work, the effect of different bone structure morphologies on permeability were examined both numerically and experimentally. Cubic and hexagonal based three dimensional scaffold structures were produced via stereolithography and 3D printing techniques. In particular, porosity percentage, pore size, and pore geometry were examined. Porosity content was varied from 30% to 70% and pore size from 0.34 mm to 3 mm. An adapted Kozeny-Carmen numerical method was applied for calculation of permeability through these structures and an experimental validation of these results was performed via a standard permeability experimental testing set-up. From the results it was determined that increased permeability was provided with the cubic rather than hexagonal structure as well as by utilizing the larger pore size and higher levels of porosity. Stereolithography was found to be the better processing technique, not only for improved micrometer scale dimensional accuracy reasons, but also due to the increase wettability found on the produced surfaces. The appropriate model constants determined in this work will allow for analysis of new alternate structure designs on the permeability of rapid prototyped synthetic bone structures.