Exponential Line Research Articles

NO and ROS implications in the organization of root system architecture.

Over the past decades the role of nitric oxide (NO) and reactive oxygen species (ROS) in signaling and cellular responses to stress has witnessed an exponential trend line. Despite advances in the subject, our knowledge of the role of NO and ROS as regulators of stress and plant growth and their implication in signaling pathways is still partial. The crosstalk between NO and ROS during root formation offers new domains to be explored, as it regulates several plant functions. Previous findings indicate that plants utilize these signaling molecules for regulating physiological responses and development. Depending upon cellular concentration, NO either can stimulate or impede root system architecture (RSA) by modulating enzymes through post-translational modifications. Similarly, the ROS signaling molecule network, in association with other hormonal signaling pathways, control the RSA. The spatial regulation of ROS controls cell growth and ROS determine primary root and act in concert with NO to promote lateral root primordia. NO and ROS are two central messenger molecules which act differentially to upregulate or downregulate the expression of genes pertaining to auxin synthesis and to the configuration of root architecture. The investigation concerning the contribution of donors and inhibitors of NO and ROS can further aid in deciphering their role in root development. With this background, this review provides comprehensive details about the effect and function of NO and ROS in the development of RSA.

Heat Exchanger Network Thermal Analysis Using Hybrid Pinch Technology

This research employs hybrid pinch analysis method to evaluate the heat exchanger network (HEN) of an existing refining plant for thermal design bottlenecks. The pinch rules and thermodynamic models were used to analyze the existing network design using available heat flow data to and from each cascade to determine the pinch temperature on incremental heat changes. The pinch point was discovered at the 6^th and 7^th temperature interval corresponding to a process pinch of 188°C with temperature above and below pinch at 193°C and 183°C respectively. The temperature profile showed two distinct regimes: exponential and linear trend lines within 0°C and 110°C which indicated an initial uneven temperature rise that later stabilized with increment proportional to the heat flow quantity within the heat exchanger with time. Furthermore, the temperature of the crude after it passed through the preheat exchanger network in the base case was found to be 242°C but through the retrofit method 275°C was achieved resulting in 33°C temperature differential. By this approach, the base case number of heat exchangers and trains were reduced from 36 and 20 to 30 and 10 respectively and an energy saving of about 19255KJ was achieved for each second the plan was operated.

Laboratory and distinct element analysis of the deformability behaviour of thin spray-on liners

Thin spray on liners (TSL) are polymeric or cement-based products that have been used for underground rock support extensively. Although linear–elastic behaviour assumptions have been attempted during numerical modelling of TSLs by researchers, TSLs do not obey this behaviour in reality. The effect of curing time on the elastic material properties (Young's modulus, Poisson's ratio) and the compressive strength of flexible and rigid liners were studied. During the laboratory studies, samples from two different TSLs (flexible and relatively rigid) prepared in laboratory conditions with different curing times (2, 7, 14, 21 and 28 days) were tested based on the ASTM standards. It is concluded that an increase in curing time improves the compressive strength and modulus of the TSLs but decreases their deformation behaviours. The relationship between Young's modulus, the curing time and uniaxial compressive strength (UCS), and the curing time can be expressed with an exponential trend line for the rigid liner and a logarithmic trend line for the flexible liner, respectively. TSLs have no definitive constitutive behaviour revealed so far. In this study, distinct element modelling of TSLs on UCS test specimens were performed to be able to capture their true constitutive stress-strain behaviour under compression. Deformation behaviours of laboratory test specimens were simulated in a DEM code, PFC2D. Finally, a new scaling coefficient between macro and micro properties of PFC for deformability testing is calculated in order to decrease the laborious calibration process that one must go through in PFC modelling. If the strength and modulus of laboratory results of TSLs are known, their micro properties can be calculated using the presented scaling coefficient given in this study.

Estimating Economic and Environmental Impacts of Red-Wine-Making Processes in the USA

The goal of this study was to examine cost impacts using techno-economic analysis (TEA) and environmental impacts using life-cycle assessment (LCA) for the production of red wine. Three production scales, denoted as “small” (5000 gal per year), “medium” (50,000 gal per year), and “large” (500,000 gal per year) were chosen for analysis. For example, the consumption of water, energy, greenhouse gas emissions, and solid waste generation were considered in order to estimate environmental impacts. A spreadsheet-based economic model was also developed. The results of the LCA and TEA were compared amongst all production scales. The results of the LCA showed that both bottle manufacturing and various wine-making processes contributed the greatest environmental impacts. For TEA, the relationships between costs and profits increased as production scale increased; exponential trend lines could describe the data, but linear models were better. This information can be useful when considering what size of winery might be appropriate to invest in, or what operational categories may be most impactful in terms of costs and environmental burdens and, thus, may be targets for efficiency improvements.

THERMAL DECOMPOSITION KINETICS OF LANTHANUM OXALATE HYDRATE PRODUCT TREATMENT FROM MONAZITE

THERMAL DECOMPOSITION KINETICS OF LANTHANUM OXALATE HYDRATE PRODUCT TREATMENT FROM MONAZITE . Unreacted shrinking core model variation was developed for calcination and solid thermal decomposition reaction to non catalytic gas and no gas reactants were involved. In this research, thermal decomposition of lanthanum oxalate hydrate product treatment of monazite. The parameters for modeling are the time and temperature of thermal decomposition. The time was between 0 - 150 minutes with 30 minute intervals and the temperature range between 600 – 700 o C with 100 o C intervals. Based on the experimental data it can be concluded that the most suitable model was unreacted core sphere ash diffusion controls and obtained the relation between temperature T o C with diffusion coefficient D following equation D = 0.0011 T + 0.5175 with linearity R² = 0.9561. Another possible model was the sphere reaction control and obtained the relationship between 1 / T (K) and reaction rate constant k s was k s = 48873.e -4.88 / RT with activation energy = 4.88 kJ. The relationship between time t with r c (radius of particles at time t) at various temperatures and the relation between temperature and r c at various times follows the exponential line equation. If temperature and time parameters were combined will find the relation between time and temperature with r c following the equation ln r c = -0.9536 (9E-04 T + 0.005 T) + 4.9976.

Exhaled air speed measurements of respiratory air flow, generated by ten different human subjects, under uncontrolled conditions

The presented study reveals a multi-point experimental measurement of the airflow speed, generated in the exhalation phase from the human respiratory cycle, based on data from 10 real human subjects. The results obtained demonstrate the exceptional irregularity and the transient character of the human respiratory cycle, in terms of measured speed at different points of man-generated exhalation air flow. The presented exponential trend lines show as expected, that there is a reduction in the exhalation speed, with the increase of the distance from the nose. The summary analysis shows that at 10 cm distance from the nose the maximum as well as the average measured speeds are higher than the one, measured at 5 cm distance. This suggests that due to the physiology of the human nose, 5 cm distance is not enough to characterize the fully developed exhalation jet flow. It is suggested that at this distance the exhalation jets are still two, issuing from each nostril, with different flowrate ratio. The obtained flow characteristics can be used to compare, validate and verify data from conducted numerical studies of the breathing process, via virtual models or real breathing thermal mannikins.

Diferansiyel Evrim Algoritması Kullanılarak Eksponansiyel Hatlar ile Alçak Geçiren Filtre Tasarımı

In this work, Differential Evolutionary Algorithm (DEA), a novel and commonly used optimization algorithm in engineering problems, is applied for the design optimization of a low pass filter with exponential transmission lines. Basically the principle of DEA is similar to genetic algorithms techniques, however compare to meta-heuristic algorithms it has a much simpler algorithm structure and higher stability compare to its counterpart algorithms. For design optimization of low pass filter with exponential transmission lines, each of the transmission lines width and variation with its length are taken as an optimization variable for DEA. Firstly the unit microstrip transmission line model is chosen. After that, the optimal value of widths and lengths are obtained via DEA. The cost function of the DEA is based on the calculation of scattering parameters of candidate's solutions crossed the requested frequency bandwidth.

CEA clearance pattern as a predictor of tumor response to neoadjuvant treatment in rectal cancer: a post-hoc analysis of FOWARC trial

BackgroundThe clinical factors that accurately predict the response to preoperative treatment in rectal cancer were yet unknown. The carcinoembryonic antigen (CEA) clearance pattern during neoadjuvant treatment has been developed and the predictive value explored in rectal cancer patients with elevated CEA levels (> 5 ng/mL).MethodsThe training cohort was derived from the FOWARC prospective phase III trial, and 71/483 eligible patients were included. The validation cohort consisted of 75/587 consecutive rectal cancer patients from Xiangya Hospital between 2014 and 2015. The kinetic changes in serum CEA were measured at different time points during the neoadjuvant treatment. An exponential trend line was drawn using the CEA values. The patients were categorized into two groups based on the R2 value of the trend line, which indicates the correlation coefficient between the exponential graph and measured CEA values: exponential decrease group (0.9 < R2 ≤ 1.0) and non-exponential decrease group (R2 ≤ 0.9).ResultsIn multivariate analysis, the patients in the CEA exponential decrease group had significantly high adequate rate of downstaging (ypT0-2N0M0), and pathologic complete response (pCR) rates after neoadjuvant treatment in the training cohort. The predictive values of the CEA clearance pattern for tumor downstaging and pCR were further confirmed in an independent validation cohort.ConclusionsThe CEA clearance pattern was an independent predictor of tumor response to neoadjuvant treatment in patients with rectal cancer. It might serve as an adjunct in the assessment of complete clinical response and guide individualized treatment strategies.Trial registrationNCT01211210.

Estimation of tumour volume at therapy initiation by back-extrapolating the post-therapy regression curve of tumour volume

BackgroundTumour volume at therapy initiation, Vi, is rarely available in cancer patients, and the last pre-treatment tumour volume available is from previous diagnostic imaging (Vd). Therapeutic efficacy is thus evaluated by comparing tumour volume after treatment with Vd, instead of Vi, which results in underestimation of treatment efficacy. Vi, together with Vd, can also be used for estimation of the natural growth rate of tumour valuable for, e.g., screening programs, prognostication and individualised treatment planning such as chemotherapy scheduling. The aim of this work was to study the feasibility of estimating Vi by back-extrapolating the post-therapy regression of tumour volume, based on data from animal model.MethodsNude mice bearing human neuroendocrine GOT1 tumour cell line were treated with 177Lu-DOTA-TATE. Tumour volumes were measured regularly after therapy and Vi was estimated by back-extrapolation of (a) linear and (b) exponential regression lines of the two earliest post-therapy tumour volumes and (c) the long-term exponential regression of tumour volume. The estimated Vi values (Vest) were compared with the measured volume of tumour at therapy initiation.ResultsThe linear regression of the two earliest post-therapy tumour volumes gave the best estimate for Vi (Vest = 0.91 Vi, p < 0.00001), compared with the exponential regression models either on short-term (Vest = 2.30 Vi, p < 0.01), or long-term (Vest = 0.93 Vi, non-significant) follow up of tumour volume after therapy.ConclusionBack-extrapolation of the early linear regression of tumour volume after therapy gave the best estimate for tumour volume at time of therapy initiation. This estimate can be used as baseline for treatment efficacy evaluation or for estimation of the natural growth rate of tumour (together with the measured tumour volume at pre-treatment diagnostic imaging).

СТАН ТА ПЕРСПЕКТИВИ РОЗВИТКУ В УКРАЇНІ СТРАХУВАННЯ ВАНТАЖІВ В ІНТЕГРОВАНИХ ТРАНСПОРТНИХ КОРИДОРАХ

В статті розглянуто сучасний стан страхування вантажів в Україні. Проведено аналіз динаміки та виявлено основні тенденції зміни страхування вантажів за показниками валових та чистих страхових премій, долі на ринку страхування та перестрахування. Сформовано перспективи розвитку страхування вантажів в Україні в інтегрованих транспортних коридорах.

Investigation on Dynamic Impact Effect of Ultrasonic-Assisted Compression Test

Ultrasonic-assisted metal forming have been studied numerously in conventional macro scale. However, ultrasonic dynamic impact effect, occurring in micro scale, has never been studied thoroughly, which makes the characteristics of material deformation more unpredictable in ultrasonic-assisted micro forming. The purpose of this study is to confirm the critical condition for occurrence of ultrasonic dynamic impact effect and to investigate the dimensional height dependency of ultrasonic dynamic impact effect on material deformation. In this paper, commercially pure aluminum 1100 with varying height (φ2×2mm, φ2×1.5mm, φ2×1mm) were selected for conventional static (without ultrasonic vibration) and ultrasonic-assisted compression tests. Ultrasonic-induced stress reduction was evaluated and the contour shape of deformed specimens was compared to investigate the ultrasonic dynamic impact effect on material deformation. The results showed that, as dimensional height of specimen decreased, ultrasonic vibration can reduce forming stress more effectively. In addition, a surprising anti-barreling shape and a significant contact surface area expansion were observed near contact surfaces in every specimen compressed with ultrasonic-assistance, indicating that additional plastic deformation can be produced by ultrasonic dynamic impact effect. An ultrasonic dynamic impact factor (y) is proposed and estimated by an exponential type trend line as y = 2.42e-1.48x for different dimensional specimen height (x) to quantify the ultrasonic dynamic impact effect. The promising prospect of ultrasonic vibration in micro-forming was demonstrated by the findings above, which helped to provide a basis to understand the underlying mechanism of ultrasonic-assisted micro forming and design the process in the future.

A trajectory for developing conceptual understanding of logarithmic relationships

While there has been a recent expansion of research related to the development of conceptual understanding of exponential relationships in individual students, the teaching and learning of logarithms continues to be understudied. In this report, I documented the mathematical progress of a classroom community as they developed an exponential number line to explore logarithmic relationships. In particular, the students in the community grappled with the ideas of coordinating arithmetic and geometric growth, made sense of fractional exponents, and interpreted logarithms statements (i.e. equations with logarithms in them) in terms of story problem and then related those interpretations to an exponential number line. The focus on logarithms was fruitful as this analysis resulted in new perspectives on how to address the conceptual difficulties students face when exploring exponential and logarithmic relationships.

Predicting a Power-Duration Curve in Elite Endurance Track Cyclists.

Keywords: Power-duration, performance modelling, track cycling. Introduction A power-duration curve provides coaches and athletes with a snapshot of the workload achievable for any given duration at a single point in time which can then be used to inform training and race strategy depending on the demands of the event. The accuracy of a power-duration curve is important to ensure it can be used to accurately predict performance. This preliminary research aims to determine whether a multi-trial protocol can be used to accurately predict the power duration curve up to the length of 20 minutes (to reflect the longest trial that is usually used) whilst incorporating an accurate prediction of the athlete’s capabilities within the severe exercise domain (typically durations shorter than 60 seconds). Furthermore, this research seeks to explore which trials can be used to most accurately predict the curve with the least amount of trials so that coaches and athletes can use the protocol without impacting heavily on their training schedule. This research has been conducted using elite track cycling endurance athletes who are typically able to achieve greater power outputs within the severe exercise domain than an elite road racing cyclist however they must still demonstrate strong aerobic capabilities to race for longer durations than a track sprint cyclist therefore this research also demonstrates the challenges in predicting a power-duration curve in a novel subject group. Methods A total of 20 (11 male, 9 female) elite track cyclists (defined as having competed for a National Cycling Federation at a major international competition within the last 2 years) aged 22±4 years completed 6 maximal time trials of differing durations (6 seconds(s), 30s, 60s, 360s, 720s, 1200s) over 2 days (3 on each) on a static cycle ergometer (Wattbike, Nottingham UK). The combination of the trials was randomized for each day but the participants always completed the trials in reverse time order. Each trial was completed seated and from a static start using the participants same individual riding positions. Participants were asked to refrain from strenuous activity for 24 hours before the trials and had 30 minutes of off the bike recovery between the 3 trials on each day and 24 hours of recovery between the two testing days to ensure they could perform their best in each trial. The average power output was recorded for each of the 6 trials completed and plotted on a power duration curve (Figure 1). Individual data points were then systematically taken out of the power duration curve to determine whether an accurate prediction could still be achieved with less trials (Figure 2). For each combination of trials, all the known power outputs (6s, 30s, 60s, 360s, 720s,1200s) were compared to the predicted power output. Figure 1. Power-duration curve predicted using 6 maximal time trials over a 2-day period. Figure 2. Power-duration curves predicted from the same data set using 2,3,4 and 6 data points. Results Protocol Key Black All 6 Green 6 360 1200 Yellow 30 360 1200 Red 6 60 Blue 360 1200 Protocol Black Green Yellow Red Blue Time (S) 6 0.0005 0.0005 0.0005 0.0005 0.0005 30 0.0005 0.0005 0.0005 0.0005 0.0005 60 0.0005 0.002 0.0005 0.333 0.0005 360 0.0005 0.0005 0.0005 0.583 0.139 720 0.317 0.544 0.811 0.0005 0.817 1200 0.0005 0.0005 0.0005 0.0005 0.355 Statistical analysis showed there to be only one known duration that could be accurately predicted by the 6 and 3 point protocols and two and three for each of the two point protocols (table 1) although each of these predicted the known points included in them due to an R value of 1.0. Based on this analysis, none of the protocols tested could be used to accurately predict most the known power-duration values. Table 1. Significance values of differences between predicted and actual power output. Limitations The results presented were calculated using an exponential line of best fit with an R value greater than .98 however this meant that the line often under-predicted power values known to be achievable even when that duration was included in the protocol. Further analysis will amend the line of best fit to go through the highest known values. So far, Paired T-tests were used to compare known power values for each duration tested against the predicted value from each protocol however this doesn’t provide a full representation of the power-duration curve, further statistical analysis is needed to determine whether any of the protocols demonstrate no significant difference across the whole line. Â

Quasielastic and low-energy inelastic neutron scattering study of HoCrO3 by high resolution time-of-flight neutron spectroscopy

In order to understand the origin of the huge quasielastic magnetic scattering observed previously with a back-scattering neutron spectrometer, we have re-investigated the low energy excitations in HoCrO3 by inelastic neutron scattering in a much wider energy range with time-of-flight neutron spectrometers. The inelastic signals are due to the excitations between the ground state doublet of the Ho ion. The quasielastic signal is due to the fluctuation of the disordered Ho moments. At low temperature the intensity of quasielastic scattering is small. It starts increasing as the temperature increases above 30 K. At the same temperature, the elastic intensity due to Ho moment ordering decreases in a similar way. This observation strengthens the hypothesis that the quasielastic scattering is due the fluctuations of the disordered Ho moments. The time scale of fluctuations has been determine from the quasielastic scattering and was found to vary from about 22 ps at K to about 2.5 ps at K. The stretched exponential line shape indicates a distribution of decay rates at low temperatures.

From exponential line to TEM horn and Vivaldi antenna

From exponential line to TEM horn and Vivaldi antenna

미세균열의 길이 및 간격 분포를 이용한 결의 평가(1)

미세균열의 길이와 간격의 분포를 이용하여 쥬라기 거창화강암에서 발달하는 결의 특성을 분석하였다. 상기 길이와 간격에 대한 분포상은 박편의 확대사진(<TEX>${\times}6.7$</TEX>)에서 도출하였다. 일차적으로, 여섯 방향의 결에 대한 길이 및 간격-누적빈도 도표를 미세균열의 길이의 밀도가 증가하는 순((<TEX>$H2{\rightarrow}R1$</TEX>)으로 배열하였다. 상기 두 종류의 도표의 결합을 통하여 다양한 파라미터를 추출하였다. 3개 채석면 및 3개 결을 대변하는 판별요소들은 파라미터의 값 사이의 상호 대비를 통하여 획득하였다. 이 연구의 분석 결과를 요약하면 다음과 같다. 여섯 방향의 결에 대한 평가는 간격(<TEX>${\alpha}$</TEX>, <TEX>${\lambda}_S$</TEX>) 및 길이(<TEX>${\beta}$</TEX>, <TEX>${\lambda}_L$</TEX>)와 관련된 두 지수 직선 사이의 (1) 교차각(<TEX>${\alpha}-{\beta}$</TEX>) 및 (2) 지수차(<TEX>${\lambda}_S-{\lambda}_L$</TEX>)과 같은 파라미터를 이용하여 수행하였다. 파라미터(1 및 2)의 값은 H(3번 결, (H1 + H2)/2) < G(2번 결, (G1 + G2)/2) < R(1번 결, (R1 + R2)/2)의 순서이다. 반면에 3개 면에 대한 상기 2개 파라미터의 값은 R < G < H의 순서이다. 한편, 두 지수 직선 사이의 수렴방향을 도출하였다. 상기 방향은 선 ol을 중심으로 하여 선 os'의 배치에 따른다. 선 ol이 좌측의 상부 영역 그리고 선 os'가 우측의 하부영역에 위치하는 경우, 상기 두 지수 직선은 Y축의 방향으로 수렴한다(R-유형). 반면에, 선 ol 및 선 os'의 배열순이 역전되었을 때에는 상기 두 선은 X축의 방향으로 수렴한다(H-유형). 특히, 두 수직선의 배열에 의하여 교차각(<TEX>${\alpha}-{\beta}$</TEX>)의 양(+) 혹은 음(-)의 값이 결정된다. 이러한 유형의 상관성 분석은 결의 상대적인 강도 평가 및 3개 채석면의 판별에 유용하다. The characteristics of the rock cleavage in Jurassic Geochang granite were analysed using the distribution of microcrack lengths and spacings. The phases of distribution of the above lengths and spacings were derived from the enlarged photomicrographs(<TEX>${\times}6.7$</TEX>) of the thin section. First, the length and spacing-cumulative diagrams for the six directions of rock cleavages were arranged in increasing order(<TEX>$H2{\rightarrow}R1$</TEX>) on the density(<TEX>${\rho}$</TEX>) of microcrack length. The various parameters were extracted through the combination of the above two types of diagrams. The discrimination factors representing the three quarrying planes and three rock cleavages were acquired through the mutual contrast between the values of parameters. The analysis results of the research are summarized as follows. The evaluation for the six directions of rock cleavages was performed using the parameters such as (1) intersection angle(<TEX>${\alpha}-{\beta}$</TEX>) and (2) exponent difference(<TEX>${\lambda}_S-{\lambda}_L$</TEX>) between two exponential straight lines related to spacing(<TEX>${\alpha}$</TEX>, <TEX>${\lambda}_S$</TEX>) and length(<TEX>${\beta}$</TEX>, <TEX>${\lambda}_L$</TEX>). The values of parameters(1 and 2) are in order of H(hardway, (H1 + H2)/2) < G(grain, (G1 + G2)/2) < R(rift, (R1 + R2)/2). On the contrary, the values of the above two parameters for three planes are in order of R < G < H. Meanwhile, the direction of convergence between two exponential straight lines was derived. The above direction is compliant to arrangement of the line os' centering around the line ol. The above two lines converge in the direction of the Y-axis when the line ol and line os' occupy the upper region on the left and the lower region on the right, respectively(R-type). On the contrary, the above two lines converge in the direction of the X-axis when the order of arrangement between line ol and line os' is reversed(H-type). Especially, the positive(+) or negative(-) value of intersection angle(<TEX>${\alpha}-{\beta}$</TEX>) is determined by the arrangement of two vertical lines. This type of correlation analysis is useful for evaluating the relative strength of rock cleavage and discriminating three quarrying planes.

Production Lead Time in Serial Lines: Evaluation, Analysis, and Control

Production Lead Time $\mbi (LT)$ is the average time a part spends in the system, being processed or waiting for processing. In systems with unlimited buffers, $\mbi LT$ may be orders of magnitude larger than the total processing time, leading to serious economic and quality problems. At present, no systematic analytical methods for evaluation, analysis, and control of $\mbi LT$ in systems with machines having up- and downtime characterized by continuous random variables are available. This paper is intended to develop such methods. Specifically, we address synchronous serial lines with exponential machines and derive formulas for $\mbi LT$ as a function of machine parameters and raw material release rate. Using these formulas, we develop methods for open- and closed-loop raw material release, which result in the desired $\mbi LT$ . For asynchronous exponential lines, we provide an upper bound on $LT$ . For non-exponential lines (e.g., Weibull, gamma, and log-normal), we offer an empirical formula for $\mbi LT$ as an affine function of the coefficient of variation. The results reported in this paper enable a new paradigm for production systems management, namely: manage a production system so that the desired $\mbi LT$ is ensured, while the throughput is maximized.

Unification of the low-energy excitation peaks in the heat capacity that appears in clathrates

We report that anomalous low-energy excitation (ALE) peaks in the heat capacity emerging from single-crystal cage materials can be successfully rationalized in terms of a single unified exponential line for a variety of type-I clathrates by employing a parameter associated with the freedom of space and the modified radii of guest atoms estimated by band calculations. The origin of these low-energy excitations is interpreted in the framework of quasiharmonic van der Waals type guest-host interactions based on a unified picture with the help of first-principles calculations. It is shown that the influence of guest-host ionic and covalent bonding interactions on the phonon anharmonicity, which have so far been considered to play an important role, are not significant as long as high symmetry of the cage structure is preserved. The dominant van der Waals interactions explain the soft vibrational modes of the rattling, which suppress phonon transport and lead to the concept of ``phonon-glass electron-crystal'' (PGEC) for thermoelectric applications. A few exceptions existing in type-I clathrates, as indicated by deviations from the unified line, suggest that a quasiharmonic potential can become more asymmetric via lower symmetry of the cage structure, towards glasslike disordered states at even lower temperatures. Although the origin of the boson peaks appearing in disordered materials is still under debate due to incomplete information on the real structure, the understanding provided by the present paper for crystalline cage materials may provide information partly applicable to other disordered systems.

Vortex with fourfold defect lines in a simple model of self-propelled particles.

We study the formation of a vortex with fourfold symmetry in a minimal model of self-propelled particles, confined inside a squared box, using computer simulations and also theoretical analysis. In addition to the vortex pattern, we observe five other regimes in the system: a homogeneous gaseous phase, band structures, moving clumps, moving clusters, and vibrating rings. All six regimes emerge from controlling the strength of noise and from the contribution of repulsion and alignment interactions. We study the shape of the vortex and its symmetry in detail. The pattern shows exponential defect lines where incoming and outgoing flows of particles collide. We show that alignment and repulsion interactions between particles are necessary to form such patterns. We derive hydrodynamical equations with an introduction of the "small deviation" technique to describe the vortex phase. The method is applicable to other systems as well. Finally, we compare the theory with the results of both computer simulations and an experiment using Quincke rotors. A good agreement between the three is observed.

Exploring the relationship between nanoscale dynamics and macroscopic rheology in natural polymer gums.

We report a study connecting the nanoscale and macroscale structure and dynamics of Acacia mearnsii gum as probed by small-angle X-ray scattering (SAXS), X-ray photon correlation spectroscopy (XPCS) and rheology. Acacia gum, in general, is a complex polysaccharide used extensively in industry. Over the analyzed concentration range (15 to 30 wt%) the A. mearnsii gum is found to have a gel-like linear rheology and to exhibit shear thinning flow behavior under steady shear. The gum solutions exhibited a steadily increasing elastic modulus with increasing time after they were prepared and also the emergence of shear thickening events within the shear thinning behavior, characteristic of associative polymers. XPCS measurements using gold nanoparticles as tracers were used to explore the microscopic dynamics within the biopolymer gels and revealed a two-step relaxation process with a partial decay at inaccessibly short times, suggesting caged motion of the nanoparticles, followed by a slow decay at later delay times. Non-diffusive motion evidenced by a compressed exponential line shape and an inverse relationship between relaxation time and wave vector characterizes the slow dynamics of A. mearnsii gum gels. Surprisingly, we have determined that the nanometer-scale mean square displacement of the nanoparticles showed a close relationship to the values predicted from the macroscopic elastic properties of the material, obtained through the rheology experiments. Our results demonstrate the potential applicability of the XPCS technique in the natural polymers field to connect their macroscale properties with their nanoscale structure and dynamics.