bluuebunny/crossref_metadata_2025 huggingface dataset:
A computerized remote table control for fast on‐line patient repositioning: Implementation and clinical feasibility
Authors: Bel A. , Petrascu O. , Van de Vondel I. , Coppens L. , Linthout N. , Verellen D. , Storme G.
Published: July 2002

A computerized remote control for a Siemens ZXT treatment couch was implemented and its characteristics were investigated to establish its feasibility for on‐line setup corrections, using portal imaging. Communication with the table was obtained by connecting it via a serial line to a work station. The treatment couch enables “goto” commands in the three main directions and around the isocenter. The accuracy of the movements after giving such a command was checked and the time for each movement was recorded. First, the movements into a single direction were studied (range of −4 to +4 cm and −4° to +4°). Each command was repeated four times. Second, the table was moved into the three main directions simultaneously. For this experiment a clinically relevant three‐dimensional (3‐D) normal distribution of shifts was used standard deviation (SD) 5 mm in the three main directions]. This latter experiment was done twice: without and with rotations (a distribution with SD 1°). During the first experiment, with shifts into one direction, no systematic deviations were found. The overall accuracy of the shifts was 0.6 mm (1 SD) in each direction and 0.04° (1 SD) for the rotations. The time required for a translation ranged between 4 and 13 s and for the rotation between 8 and 20 s. The second experiment with the 3‐D distribution of setup errors yielded an error in the 3‐D vector length equal to 0.96 mm (1 SD), independent of rotations. Shifts were performed in less than 11 s for 95% of the cases without rotations. When rotations were also performed, 95% of the movements finished in less than 16 s. In conclusion, the table movements are accurate and enable on‐line setup corrections in daily clinical practice.
Limitations of the point and line source approximations for the determination of geometry factors around brachytherapy sources
Authors: Karaiskos P. , Sakelliou L. , Sandilos P. , Vlachas L.
Published: July 2002

Geometry factors were calculated around commercially available pellets and elongated brachytherapy sources taking into account their actual active core geometries. These calculations were compared with corresponding ones derived using the point and line source approximations commonly used for the determination of geometry factors, as proposed by AAPM Task Group 43. The point source approximation was found to be efficient for the determination of geometry factors around single active pellets, even at radial distances very close to the source. It is also valid for the determination of geometry factors at radial distances from elongated brachytherapy sources of length For smaller radial distances, however, this approximation introduces significant errors, >50%, around elongated source designs, thus being unacceptable for the determination of geometry factors in this case. The line source approximation was found to accurately reproduce geometry factors around elongated brachytherapy source designs. Errors greater than 3%, due to the fact that the line source approximation ignores the radial dimension d of the source, are observed only at radial distances very close to the source at polar angles far away from their transverse bisectors. These errors depend on the ratio and increase as this ratio increases.
Measurement of dose‐rate constant for seeds with air kerma strength calibration based upon a primary national standard
Authors: Nath Ravinder , Yue Ning , Shahnazi Kambiz , Bongiorni Paul J.
Published: July 2002

Recent developments in the past two years require a significant change in the dosimetry of brachytherapy sources (Theraseed® model 200, manufactured by Theragenics Corp., Atlanta, GA). Since their introduction in 1987, the air kerma strength of sources for interstitial brachytherapy has been determined using a system of apparent activity measurement based upon the measurement of photon fluence at a reference distance along the transverse axis of the source free in air, using a NaI (T1) scintillation detector at the manufacturer's facilities. This detection system has been calibrated against a National Institute of Standards and Technology (NIST)‐traceable activity standard of a source. This system produced a highly consistent standard (within ±2%) for over 12 years, with the exception of the last source change in September 1997, which resulted in a change of 9% from the original 1987 standard. The second major development affecting dosimetry is that on 13 January 1999 a primary national standard for the air kerma strength of seeds was developed by NIST. This primary standard is based upon an absolute measurement of air kerma rate free in air at a reference distance from the source along its transverse axis using a wide angle free air chamber (WAFAC). In order to implement this new standard for the calibration of source strength in clinical dosimetry for interstitial implants, it is necessary to measure the dose‐rate constant for the seeds using a calibration of source strength based on the NIST 99 standard. In this work, a measurement of the dose‐rate constant using lithium fluoride (LiF) thermoluminescent dosimeters (TLDs) in a water equivalent solid phantom is reported. The measured value of this constant is where the unit air kerma strength is and is directly traceable to the NIST 99 standard. The implementation of the NIST 99 standard for should be accompanied by a simultaneous adoption of the new dose‐rate constant reported here. No changes in radial dose function, anisotropy function, anisotropy factor, and geometry function are needed. However, a change in prescribed dose may be necessary to deliver the same physical dose as before.
In‐phantom response of LiF TLD‐100 for dosimetry of HDR source
Authors: Pradhan Ambika S. , Quast Ulrich
Published: July 2002

An experiment was carried out to reevaluate the response of LiF TLD‐100 rods (1 mm×1 mm×6 mm) at different depths in a water substituting phantom to provide an answer to a prevailing controversy about the over‐response of LiF to the softened photon spectra of HDR source at depths in phantom due to its photon energy dependence. Claims of some authors that LiF TLDs over‐responds by 8.5% at 10 cm depth in phantom, necessitating depth‐dependent correction factors even for an source and of some others for no over‐response were evaluated. The over‐response of LiF TLD‐100 rods, against a calibrated ion chamber having a photon energy‐independent response within 2%, was found to be not exceeding 2.5% at a depth of 10 cm in the phantom as compared to a depth at 1 cm, for a precision of the order of ±1% (1σ) in the TLD measurements. By using ISO equivalent photon beams, photon energy dependence of the dosimeters was evaluated and for LiF TLD‐100 rods it was found to be in close agreement (within 3%) with the ratios of mass energy absorption coefficients of LiF and water in the range of effective photon energy from 26 keV to 1.25 MeV. Parameters that could contribute to the discrepancy in the reported values of experimental results have been discussed.
Generation of uniformly distributed dose points for anatomy‐based three‐dimensional dose optimization methods in brachytherapy
Authors: Lahanas M. , Baltas D. , Giannouli S. , Milickovic N. , Zamboglou N.
Published: July 2002

We have studied the accuracy of statistical parameters of dose distributions in brachytherapy using actual clinical implants. These include the mean, minimum and maximum dose values and the variance of the dose distribution inside the PTV (planning target volume), and on the surface of the PTV. These properties have been studied as a function of the number of uniformly distributed sampling points. These parameters, or the variants of these parameters, are used directly or indirectly in optimization procedures or for a description of the dose distribution. The accurate determination of these parameters depends on the sampling point distribution from which they have been obtained. Some optimization methods ignore catheters and critical structures surrounded by the PTV or alternatively consider as surface dose points only those on the contour lines of the PTV. and are extreme dose values which are either on the PTV surface or within the PTV. They must be avoided for specification and optimization purposes in brachytherapy. Using and the variance of D which we have shown to be stable parameters, achieves a more reliable description of the dose distribution on the PTV surface and within the PTV volume than does and Generation of dose points on the real surface of the PTV is obligatory and the consideration of catheter volumes results in a realistic description of anatomical dose distributions.
Rayleigh waves on a viscoelastic solid half-space
Authors: Romeo Maurizio
Published: July 2002

It is shown that the secular equation for Rayleigh waves propagating on a viscoelastic half-space always admits only one complex root corresponding to a surface wave. This result is proved in those cases in which the displacement field can be obtained analytically, including the isotropic case. The root is obtained in terms of complex integrals extending to the viscoelastic case, a result by Nkemzi [Wave Motion 26, 199–205 (1997)]. The wave solution is shown to represent an admissible surface wave for any viscoelastic relaxation kernel compatible with thermodynamics. A correspondence is then established between elastic and viscoelastic Rayleigh waves and their propagation properties are pointed out by an approximated analysis of the solution. Illustrative results are given by a numerical evaluation of the complex root for anisotropic viscoelastic half-spaces.
Theory of non-collinear interactions of acoustic waves in an isotropic material with hysteretic quadratic nonlinearity
Authors: Gusev Vitalyi
Published: July 2002

A particular form of the energy potential (cubic in strains) is proposed, which leads to the bow-tie behavior of the nonlinear modulus in an isotropic material with hysteresis of quadratic nonlinearity. The nonlinear scattering of a weak probe wave in the field of a strong pump wave is analyzed. It is demonstrated that collinear interactions of the shear waves are allowed in materials with nonlinearity hysteresis. Both in collinear and non-collinear frequency-mixing processes the combination frequency is composed of the probe wave frequency and one of the even harmonics of the pump wave. In general, the developed theory predicts that in the presence of the hysteretic nonlinearity the number of possible resonant scattering processes increases. In particular, if frequency-mixing processes are forbidden in the material with the elastic quadratic nonlinearity (for a fixed ratio of primary frequencies), they may be allowed in the materials with hysteretic quadratic nonlinearity. Moreover, in materials with hysteresis of the nonlinearity the resonant frequency mixing for a fixed ratio of primary frequencies may be allowed for multiple mutual orientations of the primary wave vectors.
Auditory display of knee-joint vibration signals
Authors: Krishnan Sridhar , Rangayyan Rangaraj M. , Bell G. Douglas , Frank Cyril B.
Published: July 2002

Sounds generated due to rubbing of knee-joint surfaces may lead to a potential tool for noninvasive assessment of articular cartilage degeneration. In the work reported in the present paper, an attempt is made to perform computer-assisted auscultation of knee joints by auditory display (AD) of vibration signals (also known as vibroarthrographic or VAG signals) emitted during active movement of the leg. Two types of AD methods are considered: audification and sonification. In audification, the VAG signals are scaled in time and frequency using a time-frequency distribution to facilitate aural analysis. In sonification, the instantaneous mean frequency and envelope of the VAG signals are derived and used to synthesize sounds that are expected to facilitate more accurate diagnosis than the original signals by improving their aural quality. Auditory classification experiments were performed by two orthopedic surgeons with 37 VAG signals including 19 normal and 18 abnormal cases. Sensitivity values (correct detection of abnormality) of 31%, 44%, and 83%, and overall classification accuracies of 53%, 40%, and 57% were obtained with the direct playback, audification, and sonification methods, respectively. The corresponding d′ scores were estimated to be 1.10, −0.36, and 0.55. The high sensitivity of the sonification method indicates that the technique could lead to improved detection of knee-joint abnormalities; however, additional work is required to improve its specificity and achieve better overall performance.
Fundamental precision limitations for measurements of frequency dependence of backscatter: Applications in tissue-mimicking phantoms and trabecular bone
Authors: Wear Keith A.
Published: July 2002

Various models for ultrasonic scattering from trabecular bone have been proposed. They may be evaluated to a certain extent by comparison with experimental measurements. In order to appreciate limitations of these comparisons, it is important to understand measurement precision. In this article, an approach proposed by Lizzi and co-workers is adapted to model precision of estimates of frequency-dependent backscatter for scattering targets (such as trabecular bone) that contain many scatterers per resolution cell. This approach predicts uncertainties in backscatter due to the random nature of the interference of echoes from individual scatterers as they are summed at the receiver. The model is validated in experiments on a soft-tissue-mimicking phantom and on 24 human calcaneus samples interrogated in vitro. It is found that while random interference effects only partially explain measured variations in the magnitude of backscatter, they are virtually entirely responsible for observed variations in the frequency dependence (exponent of a power law fit) of backscatter.
High power ultrasound standard
Authors: Wong George S. K. , Wu Lixue
Published: July 2002

A sensitive radiation force balance for laboratory measurement of ultrasonic power is presented. The principle of the system is based on measuring the ultrasonic radiation force exerted on a conical float suspended in water. Technical details of the implementation of the economically attractive system are described. The operation of the system is automated with the aid of the IEEE-488 bus and a desktop computer. Design aspects that affect measurement uncertainty are investigated. A theoretical model for the measurement of ultrasonic power with a conical reflector target is discussed. The expanded uncertainty (95% confidence level) of the above radiation force conical float system is estimated to be between 5% to 10%.
Effects of shear elasticity on sea bed scattering: Numerical examples
Authors: Ivakin Anatoliy N. , Jackson Darrell R.
Published: July 2002

It is known that marine sediments can support both compressional and shear waves. However, published work on scattering from irregular elastic media has not examined the influence of shear on sea bed scattering in detail. A perturbation model previously developed by the authors for joint roughness-volume scattering is used to study the effects of elasticity for three sea bed types: sedimentary rock, sand with high shear speed, and sand with “normal” shear wave speed. Both bistatic and monostatic cases are considered. For sedimentary rock it is found that shear elasticity tends to increase the importance of volume scattering and decrease the importance of roughness scattering relative to the fluid case. Shear effects are shown to be small for sands.
The recognition of vowels produced by men, women, boys, and girls by cochlear implant patients using a six-channel CIS processor
Authors: Loizou Philipos C. , Dorman Michael F. , Powell Verelle
Published: July 2002

Five patients who used a six-channel, continuous interleaved sampling (CIS) cochlear implant were presented vowels, in two experiments, from a large sample of men, women, boys, and girls for identification. At issue in the first experiment was whether vowels from one speaker group, i.e., men, were more identifiable than vowels from other speaker groups. At issue in the second experiment was the role of the fifth and sixth channels in the identification of vowels from the different speaker groups. It was found in experiment 1 that (i) the vowels produced by men were easier to identify than vowels produced by any of the other speaker groups, (ii) vowels from women and boys were more difficult to identify than vowels from men but less difficult than vowels from girls, and (iii) vowels from girls were more difficult to identify than vowels from all other groups. In experiment 2 removal of channels 5 and 6 from the processor impaired the identification of vowels produced by women, boys and girls but did not impair the identification of vowels produced by men. The results of experiment 1 demonstrate that scores on tests of vowels produced by men overestimate the ability of patients to recognize vowels in the broader context of multi-talker communication. The results of experiment 2 demonstrate that channels 5 and 6 become more important for vowel recognition as the second formants of the speakers increase in frequency.
The psychological cost of aircraft noise for children
Authors: Mackensen Sylvia V. , Bullinger Monika , Meis Markus , Evans Gary W. , Hygge Staffan
Published: July 2002

Psychological effects of aircraft noise exposure on children have only recently been addressed in the literature. The current study took advantage of a natural experiment by the opening of a new airport, exposing formerly nonexposed children to low aircraft noise. In this prospective longitudinal investigation, which employed nonexposed control groups, effects of aircraft noise prior to inauguration of the new airport, as well as effects of chronic noise and its reduction at the old airport, were studied in children aged 9 to 13 years. The psychological health of children was investigated with a standarized quality of life scale as well as with a motivational measure. In addition, a self-report noise annoyance scale was used. In the 393 children studied at the new airport over three time points, results showed a significant decrease of total quality of life 18 months after aircraft noise exposure, as well as a motivational deficit in the new airport area. In the old airport, parallel impairments were present before the airport relocation but subsided thereafter. These findings are in accord with reports of impaired psychological health after noise exposure and indicate the relevance of monitoring psychological parameters as a function of environmental stressors among children.
Vowel-specific effects in concurrent vowel identification
Authors: de Cheveigné Alain
Published: July 2002

An experiment investigated the effects of amplitude ratio (−35 to 35 dB in 10-dB steps) and fundamental frequency difference (0%, 3%, 6%, and 12%) on the identification of pairs of concurrent synthetic vowels. Vowels as weak as −25 dB relative to their competitor were easier to identify in the presence of a fundamental frequency difference (ΔF0). Vowels as weak as −35 dB were not. Identification was generally the same at ΔF0=3%, 6%, and 12% for all amplitude ratios: unfavorable amplitude ratios could not be compensated by larger ΔF0’s. Data for each vowel pair and each amplitude ratio, at ΔF0=0%, were compared to the spectral envelope of the stimulus at the same ratio, in order to determine which spectral cues determined identification. This information was then used to interpret the pattern of improvement with ΔF0 for each vowel pair, to better understand mechanisms of F0-guided segregation. Identification of a vowel was possible in the presence of strong cues belonging to its competitor, as long as cues to its own formants F1 and F2 were prominent. ΔF0 enhanced the prominence of a target vowel’s cues, even when the spectrum of the target was up to 10 dB below that of its competitor at all frequencies. The results are incompatible with models of segregation based on harmonic enhancement, beats, or channel selection.
The radiating near field of a circular normal transducer of arbitrary apodization on an elastic half-space
Authors: Gridin Dmitri
Published: July 2002

A new fast method is developed for simulating the propagation of pulses radiated by a circular normal transducer of arbitrary apodization into an isotropic and homogeneous elastic half-space. First, the model proposed in Fradkin, Kiselev and Krylova for a time-harmonic uniform transducer [J. Acoust. Soc. Am. 104, 1178–1187 (1998)] is extended to the case of nonuniform load to obtain high-frequency asymptotics of the time-harmonic field. Then, the transient field is described by means of harmonic synthesis. The asymptotics elucidate the physics of the problem and give explicit dependence of the radiated waves on model parameters. The formulas are applicable in the radiating near field, that is the near field with the evanescent wave zone excluded. They involve in geometrical regions elementary and inside boundary layers, well-known special functions (Fresnel integral and Bessel functions). Unlike the uniform load case, the direct shear wave is present and the edge waves may be practically eliminated. The asymptotic code has been tested against an exact numerical solution when apodization is parabolic. It has proved to be hundreds of times faster but in many realistic cases the accuracy does not suffer much.
Magnetic excitation and acoustical detection of torsional and quasi-flexural modes of spherical shells in water
Authors: Hefner Brian T. , Marston Philip L.
Published: July 2002

A simple electromagnetic acoustic wave transducer (EMAT) based on a wire coil was used to excite the resonant modes of a stainless steel spherical shell without direct mechanical contact. The coupling produced by this EMAT was examined first for shells in air and then for shells immersed in water to examine the effects of fluid loading on the shell’s spectrum. It was found that the torsional modes were excited using this method and these modes radiated sound into the surrounding water contrary to expectations. This excitation is shown to depend on the presence of a permanent magnetization in the shell itself or on the presence of a static external field applied at right angles to the axis of the coil. Possible mechanisms for the excitation and the acoustic radiation of the torsional modes are considered. The excitation of quasi-flexural shell modes is also discussed for shells in air and in water. The shell responds at the oscillation frequency of the applied field and at twice the frequency. Some potential applications of this method of measuring modes are noted.
Rate-intensity functions in the emu auditory nerve
Authors: Yates Graeme K. , Manley Geoffrey A. , Köppl Christine
Published: July 2002

Rate-versus-intensity functions recorded from mammalian auditory-nerve fibers have been shown to form a continuum of shapes, ranging from saturating to straight and correlating well with spontaneous rate and sensitivity. These variations are believed to be a consequence of the interaction between the sensitivity of the hair-cell afferent synapse and the nonlinear, compressive growth of the cochlear amplifier that enhances mechanical vibrations on the basilar membrane. Little is known, however, about the cochlear amplifier in other vertebrate species. Rate-intensity functions were recorded from auditory-nerve fibers in chicks of the emu, a member of the Ratites, a primitive group of flightless birds that have poorly differentiated short and tall hair cells. Recorded data were found to be well fitted by analytical functions which have previously been shown to represent well the shapes of rate-intensity functions in guinea pigs. At the fibers’ most sensitive frequencies, rate-intensity functions were almost exclusively of the sloping (80.9%) or straight (18.6%) type. Flat-saturating functions, the most common type in the mammal, represented only about 0.5% of the total in the emu. Below the best frequency of each fiber, the rate-intensity functions tended more towards the flat-saturating type, as is the case in mammals; a similar but weaker trend was seen above best frequency in most fibers, with only a small proportion (18%) showing the reverse trend. The emu rate-intensity functions were accepted as supporting previous evidence for the existence of a cochlear amplifier in birds, the conclusion was drawn further that the nonlinearity observed is probably due to saturation of the hair-cell transduction mechanism.
Effect of speaking rate and contrastive stress on formant dynamics and vowel perception
Authors: Pitermann Michel
Published: July 2002

Vowel formants play an important role in speech theories and applications; however, the same formant values measured for the steady-state part of a vowel can correspond to different vowel categories. Experimental evidence indicates that dynamic information can also contribute to vowel characterization. Hence, dynamically modeling formant transitions may lead to quantitatively testable predictions in vowel categorization. Because the articulatory strategy used to manage different speaking rates and contrastive stress may depend on speaker and situation, the parameter values of a dynamic formant model may vary with speaking rate and stress. In most experiments speaking rate is rarely controlled, only two or three rates are tested, and most corpora contain just a few repetitions of each item. As a consequence, the dependence of dynamic models on those factors is difficult to gauge. This article presents a study of 2300 [iai] or [iɛi] stimuli produced by two speakers at nine or ten speaking rates in a carrier sentence for two contrastive stress patterns. The corpus was perceptually evaluated by naive listeners. Formant frequencies were measured during the steady-state parts of the stimuli, and the formant transitions were dynamically and kinematically modeled. The results indicate that (1) the corpus was characterized by a contextual assimilation instead of a centralization effect; (2) dynamic or kinematic modeling was equivalent as far as the analysis of the model parameters was concerned; (3) the dependence of the model parameter estimates on speaking rate and stress suggests that the formant transitions were sharper for high speaking rate, but no consistent trend was found for contrastive stress; (4) the formant frequencies measured in the steady-state parts of the vowels were sufficient to explain the perceptual results while the dynamic parameters of the models were not.
Rheological Properties of Three Solutions. Part II. Relaxation and Growth of Shear and Normal Stresses
Authors: Huppler J. D. , Macdonald I. F. , Ashare E. , Spriggs T. W. , Bird R. B. , Holmes L. A.
Published: July 2002

The same three solutions used in Part I were used to measure stress relaxation after the cessation of steady simple shear flow and stress growth after the onset of steady simple shear flow. Both shear and normal stress difference responses were measured. In addition, “interrupted flow,” a turret-shaped function for the velocity gradient, was studied. The data are used to evaluate the three rheological models considered in Part I. These models all make the same predictions for stress relaxation. They differ markedly in their predictions for stress growth; the OWFS model predicts no overshoot, the WJFLMB model predicts a single overshoot, and the Spriggs 4-constant model predicts oscillatory behavior. The models satisfactorily describe the stress relaxation data but fail to describe the stress growth data.
Evaluation of Internal Viscosity Models
Authors: Zimmerman R. D. , Williams Michael C.
Published: July 2002

Four versions of the internal viscosity model are summarized and examined with respect to their ability to fit experimental stress data. Emphasis is placed on model C II, one of three proposed by Cerf and the most widely known. Model predictions are compared simultaneously with data on non-Newtonian viscosity, normal stress coefficient, and complex viscosity components for each of several solutions of monodisperse polystyrene in Aroclor. It is concluded that all four models suffer from defects that may limit their applicability for engineering purposes, but that some may have further utility for describing ideally dilute solution behavior.
State diagrams of soy globulins
Authors: Morales Alfredo , Kokini Jozef L.
Published: July 2002

State transitions of 7S and 11S soy globulins were studied as a function of moisture by monitoring their rheological and calorimetric properties. Small-amplitude oscillatory rheometry and differential scanning calorimetry (DSC) were used to characterize their denaturation and complexing reactions within a temperature range of 40–200 °C and moisture contents of approximately 20%, 30%, and 40%. Major increases in rheological properties showed that the 7S and 11S fractions with 40% moisture underwent structure forming reactions above 70 and 100 °C, respectively, while they reacted at higher temperatures for lower moisture. DSC helped to identify the individual complexing behavior of each fraction. The above, along with the information from their glass transition, previously reported, allowed us to develop state diagrams for each protein, where glassy, rubbery, entangled polymer, reaction, and free-flow states were identified.
Rheological properties of two polypropylenes with different molecular structure
Authors: Kurzbeck S. , Oster F. , Münstedt H. , Nguyen T. Q. , Gensler R.
Published: July 2002

Two polypropylenes with different molecular structure were investigated in shear and elongational flow. One resin is an ethylene–propylene copolymer with linear molecules and the other is a long-chain branched propylene homopolymer. The elongational flow behavior was investigated in stressing and creep experiments. For the linear material no strain hardening can be observed whereas the strain-hardening behavior of the long-chain branched material is more pronounced than it was found for any other polyolefin up to now. The branched resin also exhibits high recoverable strains. The strain-hardening behavior is analyzed with respect to its strain and strain rate dependence. The results are discussed with regard to the molecular structure. The coexistence of a long-chain branched structure and a high molecular weight component is assumed to be the reason for the outstanding elongational flow behavior of the branched polypropylene.
Śaiva Siddhānta
Authors: Bartley Christopher
Published: June 2022

Śaiva Siddhānta is a Tantric but Veda‐congruent dualist tradition of ritualistic monotheism. The deity Śiva is held to be well‐disposed toward human beings, for whose release from rebirth the cosmos of worlds is graciously created. This religion provides explanations for the souls' bondage to rebirth, a path to salvation, and an account of the nature of the liberated condition. Śaiva Siddhāntin thinkers formulate critiques of rival theories, especially the process‐ontologies propounded by Buddhists. In the context of a substance‐ontology, they articulate a view of human selves as enduring realities whose essential properties are consciousness and agency.
Experiences and viewpoints of PhD students completing their dissertations during crises
Authors: Znamenak Kyle , Lieberth Mitch , Murphy Jennifer L. , Sheaffer Auburn
Published: June 2022

This article narrates the experiences of four former PhD students who completed the transition from graduate student to graduates with PhDs during unprecedented external events: The COVID‐19 pandemic and a period of civil unrest in response to the 2020 police killings of George Floyd and Breonna Taylor. The authors reflect on some commonalities in how they were able to adjust and persevere to completion.
Conversations with leaders: Sharing perspectives on the impact of and response to COVID‐19 and other crises
Authors: Schmidt Steven W. , English Leona M. , Carr‐Chellman Ali
Published: June 2022

Lessons learned during the COVID‐19 pandemic, through trial and error and sharing stories of successes and failures, have resulted in progress in the quest to resume what we refer to as normal or regular college life for students, faculty, and staff. However, it is doubtful that we will ever get back to the exact same situation that we were in prior to March of 2020, and that may not even be an appropriate goal for which to strive. We can learn from this pandemic and continuously improve what we do based on lessons learned rather than simply focusing on getting back to some sort of prepandemic “normal” state. This article and this entire edition of New Directions for Adult and Continuing Education are part of those efforts to document our experiences so we all can learn from them and move forward with that knowledge in mind.
Multiomic Analyses of Nascent Preterm Infant Microbiomes Differentiation Suggest Opportunities for Targeted Intervention
Authors: Orchanian Stephanie B. , Gauglitz Julia M. , Wandro Stephen , Weldon Kelly C. , Doty Megan , Stillwell Kristina , Hansen Shalisa , Jiang Lingjing , Vargas Fernando , Rhee Kyung E. , Lumeng Julie C. , Dorrestein Pieter C. , Knight Rob , Kim Jae H. , Song Se Jin , Swafford Austin D.
Published: June 2022

The first week after birth is a critical time for the establishment of microbial communities for infants. Preterm infants face unique environmental impacts on their newly acquired microbiomes, including increased incidence of cesarean section delivery and exposure to antibiotics as well as delayed enteral feeding and reduced human interaction during their intensive care unit stay. Using contextualized paired metabolomics and 16S sequencing data, the development of the gut, skin, and oral microbiomes of infants is profiled daily for the first week after birth, and it is found that the skin microbiome appears robust to early life perturbation, while direct exposure of infants to antibiotics, rather than presumed maternal transmission, delays microbiome development and prevents the early differentiation based on body site regardless of delivery mode. Metabolomic analyses identify the development of all gut metabolomes of preterm infants toward full‐term infant profiles, but a significant increase of primary bile acid metabolism only in the non‐antibiotic treated vaginally birthed late preterm infants. This study provides a framework for future multi‐omic, multibody site analyses on these high‐risk preterm infant populations and suggests opportunities for monitoring and intervention, with infant antibiotic exposure as the primary driver of delays in microbiome development.
Cyclic Stability of Ni44.8Cu5Ti45.2Hf5 and Zr‐Substituted Ni44.8Cu5Ti40.2Hf5Zr5 Medium‐Entropy Shape Memory Alloys
Authors: Baradari Sadjad , Resnina Natalia , Belyaev Sergey , Nili-Ahmadabadi Mahmoud
Published: June 2022

An experimental investigation on the cyclic stability of solutionized Ni44.8Cu5Ti45.2Hf5 and Zr‐substituted Ni44.8Cu5Ti40.2Hf5Zr5 (atomic percent, at%) medium‐entropy shape memory alloys (MESMAs) was carried out. The shift of the peak temperature for the forward B2B19′ transformation in Ni44.8Cu5Ti45.2Hf5 alloy after 50 differential scanning calorimetry (DSC) cycles was measured to be 23 °C, substituting 5 at% Zr for Ti increased it to 41 °C. No residual strain accumulation was observed in Ni44.8Cu5Ti45.2Hf5 alloy after 10 thermal cycles under a tensile stress of 200 MPa, and meanwhile the shape memory strain increased from 5% to 6.5%. A pseudoelastic strain (εPE) of ≈2.7% was obtained in Zr‐substituted Ni44.8Cu5Ti40.2Hf5Zr5 alloy at 55 °C (Af + 10 °C) for a maximum deformation (εmax.) of 4.4%. In addition, the stability of pseudoelasticity in Ni44.8Cu5Ti40.2Hf5Zr5 alloy during 100 loading–unloading cycles was examined in the solution annealed (1000 °C for 1 h) and aged (400 °C for 1 h) conditions. The results showed that aging treatment could effectively retard the degradation of pseudoelasticity in the alloy. These preliminary findings suggest that the idea of increasing chemical complexity in NiTi‐based SMAs holds promising potential in developing novel SMAs with enhanced cyclic stability.
Snake Venom Hydrogels as a Rapid Hemostatic Agent for Uncontrolled Bleeding
Authors: Yegappan Ramanathan , Lauko Jan , Wang Zhao , Lavin Martin F. , Kijas Amanda W. , Rowan Alan E.
Published: June 2022

Uncontrolled bleeding from traumatic injury remains the leading cause of preventable death with loss of balance between blood clotting (coagulation) and blood clot breakdown (fibrinolysis). A major limitation of existing hemostatic agents is that they require a functioning clotting system to control the bleeding and are largely based on gauze delivery scaffolds. Herein, a novel rapid wound sealant, composed of two recombinant snake venom proteins, the procoagulant ecarin, to rapidly initiate blood clotting and the antifibrinolytic textilinin, to prevent blood clot breakdown within a synthetic thermoresponsive hydrogel scaffold is developed. In vitro, it is demonstrated that clotting is rapidly initiated with only nanomolar concentrations of venom protein and clot breakdown is effectively inhibited by textilinin. A stable clot is formed within 60 s compared to normal clot formation in 8 min. In vivo studies reveal that the snake venom hydrogel rapidly controls warfarin‐induced bleeding, reducing the bleed volume from 48% to 12% and has demonstrated immune compatibility. A new class of hemostatic agents that achieve formation of rapid and stable blood clots even in the presence of blood thinners is demonstrated here.
Bile Acid Conjugation on Solid Nanoparticles Enhances ASBT‐Mediated Endocytosis and Chylomicron Pathway but Weakens the Transcytosis by Inducing Transport Flow in a Cellular Negative Feedback Loop
Authors: Deng Feiyang , Kim Kyoung Sub , Moon Jiyoung , Bae You Han
Published: June 2022

Bile acid‐modified nanoparticles provide a convenient strategy to improve oral bioavailability of poorly permeable drugs by exploiting specific interactions with bile acid transporters. However, the underlying mechanisms are unknown, especially considering the different absorption sites of free bile acids (ileum) and digested fat molecules from bile acid‐emulsified fat droplets (duodenum). Here, glycocholic acid (GCA)‐conjugated polystyrene nanoparticles (GCPNs) are synthesized and their transport in Caco‐2 cell models is studied. GCA conjugation enhances the uptake by interactions with apical sodium‐dependent bile acid transporter (ASBT). A new pathway correlated with both ASBT and chylomicron pathways is identified. Meanwhile, the higher uptake of GCPNs does not lead to higher transcytosis to the same degree compared with unmodified nanoparticles (CPNs). The pharmacological and genomics study confirm that GCA conjugation changes the endocytosis mechanisms and downregulates the cellular response to the transport at gene levels, which works as a negative feedback loop and explains the higher cellular retention of GCPNs. These findings offer a solid foundation in the bile acid‐based nanomedicine design, with utilizing advantages of the ASBT‐mediated uptake, as well as inspiration to take comprehensive consideration of the cellular response with more developed technologies.
Unified Picture of (Non)Hysteretic Oxygen Capacity in O3‐Type Sodium 3d Layered Oxides
Authors: Lee Jaewoon , Park Sangeon , Choi Gwanghyeon , Kwon Dohyeong , Kim Jongbeom , Kim Hyungjun , Cho Maenghyo , Kim Duho
Published: June 2022

A unified picture of the generalized mechanism that elucidates the (non)hysteretic oxygen capacities of O3‐type Na1−x[Li2/6Mn3/6M1/6]O2 (M = Mn4+, Ni4+, and Ti4+) layered oxides is suggested to provide a critical factor in inducing ideal reversibility for an oxygen redox (OR) reaction using the new concept, the “potential‐pillar” effect. Considering that there is no formation of interlayer oxygen–oxygen (OO) dimers at x = 1.0 in Na1−x[Li2/6Mn3/6Ti1/6]O2, the phase stabilities reveal that the biphasic reaction occurs in Na1−x[Li2/6Mn3/6Ni1/6]O2 (0.5 ≤ x ≤ 1.0), and the monophasic reaction takes place in Na1−x[Li2/6Mn3/6Ti1/6]O2 during desodiation. The electronic structures of cations and anions unambiguously show OR reactions over the full vacancy range, and the oxygen ions comprising TiO6 are relatively deactivated compared with those of NiO6 upon electrochemical OR reaction. This is deemed as an intriguing “potential‐pillar” effect, in which the chemically stiff Ti4+(3d)O(2p) bond locally retains a strong electrostatic repulsion between the mixed layers. This unified concept based on an in‐depth understanding of the three cathode models not only accounts for the origin of the (non)hysteretic oxygen capacities, but also provides an exciting local structure viewpoint for harnessing the full potential of OR reactions for high energy‐density sodium‐ion batteries.
Synthesis of self‐healing soybean oil‐based waterborne polyurethane based on Diels–Alder reaction
Authors: Chen Liang , Dai Zhuding , Lou Wenxue , Jiang Pingping , Zhang Pingbo , Bao Yanmin , Gao Xuewen , Xia Jialiang
Published: June 2022

In order to endow water‐based polyurethane with special functionality, vegetable oil‐based waterborne polyurethane with self‐healing properties is synthesized. Firstly, soybean oil‐based emulsifier (GA‐ESO) was prepared by epoxy soybean oil and glutaric acid without solvent and catalyst. Then, two Diels−Alder (DA) diols were prepared by the DA reaction between N,N′‐(4,4′‐methyldiphenyl) bismaleimide, 4‐maleimide phenol and furfuryl alcohol, respectively. Finally, GA‐ESO and DA diols used as the raw material was reacted with isophorone diisocyanate to synthesize a series of soybean oil‐based waterborne polyurethane with self‐healing behavior. The effects of DA diol on the properties of polyurethane films and the self‐healing process and mechanism of polyurethane membrane were investigated. The results showed that after the addition of DA diol, the particle size of polyurethane emulsion increased from 28.8 to 85.3 nm, the tensile strength was improved from 0.3 to 12.6 MPa, and the water contact angle was enhanced from 68.5° to 84.2°. In addition, it can be observed that with the addition of DAdiol, the polyurethane film had self‐healing behavior at high temperature, and the highest self‐healing efficiency can reach 100%.
QM/MM Calculations Suggest Concerted O−O Bond Cleavage and Substrate Oxidation by Nonheme Diiron Toluene/o‐Xylene Monooxygenase
Authors: Zhou Tai‐Ping , Deng Wen‐Hao , Wu Yuzhou , Liao Rong‐Zhen
Published: June 2022

The nonheme diiron toluene/o‐xylene monooxygenase (ToMO) is the most studied toluene monooxygenase that mediates an aromatic hydroxylation reaction. In this work, QM/MM calculations were performed to understand the reaction mechanism. It is revealed that the μ‐η2:η2 peroxodiferric species is the reactive intermediate after the binding of the O2 molecule to the reduced diferrous center. Subsequently, both a stepwise and a concerted mechanism involving the critical O−O bond cleavage and C−O bond formation were considered. The latter was calculated to be more favorable, suggesting that the formation of a high‐valent diferryl Q intermediate is not needed. The isomeric formation of the phenol product was found very facile. The first step was calculated to be rate‐limiting, with a barrier of 17.6 kcal/mol for the ortho‐hydroxylation.
Compartmentalized microfluidic device for in vitro co‐culture of retinal cells
Authors: Jahagirdar Devashree , Yadav Shital , Gore Manish , Korpale Vikram , Mathpati Channamallikarjuna S. , Chidambaram Subbulakshmi , Majumder Abhijit , Jain Ratnesh , Dandekar Prajakta
Published: June 2022

The investigation is focused on the development of a compartmentalized microfluidic device for coculturing the cells of crucial retinal cellular layers and assessing cell‐to‐cell interactions. A perfusion‐based microfluidic co‐culture device was employed and computationally validated for determining the pressure drop and fluid flow rate within the device microchannels. Fabrication was performed using PDMS polymer and coating of fibronectin and collagen facilitated adherence of the cells over the glass surface. Microfluidic device successfully supported cell proliferation, under continuous perfusion of 1 μl min‐1 flow rate. The barrier integrity of this coculture was confirmed by evaluating the permeability of fluorescently labeled molecules. The coculture expressed characteristic phenotypic protein markers like recoverin, PAX6, for retinal precursor cells, and RPE65 for retinal epithelial cells. The coculture also exhibited basal expression of TNF‐α under normal conditions. Differentiated photoreceptor cells positively expressed rhod inherently possess sensitivity toward violet/blue light, which was validated in R28 cells by exposure to light having a wavelength of 405 nm, which significantly decreased cell viability via increased TNF‐α production and reduced rhodopsin expression. This proof‐of‐concept investigation proved the functionality of the retinal coculture, which may be used as an appropriate perfusion‐based, preclinical tool for the evaluation of novel retinal drugs and delivery systems.
Enantioselective halogenation via asymmetric phase‐transfer catalysis
Authors: Lee Sunggi , Chung Won‐jin
Published: June 2022

The asymmetric phase‐transfer catalysis (PTC) is a flourishing field of contemporary synthetic organic chemistry, and this prominent methodology has been tremendously successful in enantioselective halogenations. Both electrophilic and nucleophilic reaction manifolds were enabled through the exploitation of highly ordered ion pairing and/or hydrogen‐bonding interactions around a carefully designed chiral phase‐transfer catalyst with an insoluble halogenating reagent as well as a suitable substrate. Fluorination has been the most fruitful, and encouraging results have also been documented with heavier halogens. This review surveys examples of various enantioselective halogenations via the asymmetric PTC from its beginning to prosperity over the past decade.
Modeling Parkinson's disease‐related symptoms in alpha‐synuclein overexpressing mice
Authors: Aniszewska Agata , Bergström Joakim , Ingelsson Martin , Ekmark‐Lewén Sara
Published: June 2022

Background

Intracellular deposition of alpha‐synuclein (α‐syn) as Lewy bodies and Lewy neurites is a central event in the pathogenesis of Parkinson's disease (PD) and other α‐synucleinopathies. Transgenic mouse models overexpressing human α‐syn, are useful research tools in preclinical studies of pathogenetic mechanisms. Such mice develop α‐syn inclusions as well as neurodegeneration with a topographical distribution that varies depending on the choice of promoter and which form of α‐syn that is overexpressed. Moreover, they display motor symptoms and cognitive disturbances that to some extent resemble the human conditions.

Purpose

One of the main motives for assessing behavior in these mouse models is to evaluate the potential of new treatment strategies, including their impact on motor and cognitive symptoms. However, due to a high within‐group variability with respect to such features, the behavioral studies need to be applied with caution. In this review, we discuss how to make appropriate choices in the experimental design and which tests that are most suitable for the evaluation of PD‐related symptoms in such studies.

Methods

We have evaluated published results on two selected transgenic mouse models overexpressing wild type (L61) and mutated (A30P) α‐syn in the context of their validity and utility for different types of behavioral studies.

Conclusions

By applying appropriate behavioral tests, α‐syn transgenic mouse models provide an appropriate experimental platform for studies of symptoms related to PD and other α‐synucleinopathies.