On calibration of piezoelectric sensors with laser doppler vibrometer.

We present a method for calibrating piezoelectric sensors using a laser Doppler vibrometer. Our method uses an average of Fourier transform terms of the recorded signal from the piezoelectric sensor, which is compared with the laser probe measurement in the overlapping frequency range. We use our method to calibrate the response of miniature needle sensors employed in acoustic emission testing to several different excitation sources of stress waves in the frequency range of 20-300 kHz. We demonstrate that the output of the piezoelectric sensors can be accurately scaled with particle velocity.

An ultrasound probe array for a high-pressure, high-temperature solid medium deformation apparatus.

Inelastic deformation of minerals and rocks is associated with activation of various defects such as fractures, twins, and dislocations. Active and passive ultrasound probes are potential tools to examine the nature of these defects under a broad range of pressure and temperature conditions. Here, we report on the development of an ultrasound probe array that allows us to monitor deforming samples in a high-pressure, high-temperature solid medium apparatus (a modified Griggs rig). We utilize several broadband miniature piezoelectric sensors that are placed above and below the sample to record acoustic emissions accompanying deformation and determine their locations in 1D. The emissions are recorded at 50 MS/s with a 12 bit resolution. Proper grounding and electric insulation of the sensors, together with optimized power delivery from the heating system, tremendously reduces electromagnetic interference and allows for a background noise level of ≈90 mV at a full range of ±2 V and 60 dB amplification. The system is capable of recording acoustic waves from 80 kHz to 2.5 MHz at sample temperatures up to 1100 °C and confining pressure up to 2.5 GPa.

Solitonic State in Microscopic Dynamic Failures.

Onset of permanent deformation in crystalline materials under a sharp indenter tip is accompanied by nucleation and propagation of defects. By measuring the spatio-temporal strain field near the indenter tip during indentation tests, we demonstrate that the dynamic strain history at the moment of a displacement burst carries characteristics of the formation and interaction of local excitations, or solitons. We show that dynamic propagation of multiple solitons is followed by a short time interval where the propagating fronts can accelerate suddenly. As a result of such abrupt local accelerations, duration of the fast-slip phase of a failure event is shortened. Our results show that formation and annihilation of solitons mediate the microscopic fast weakening phase, during which extreme acceleration and collision of solitons lead to non-Newtonian behavior and Lorentz contraction, i.e., shortening of solitons' characteristic length. The results open new horizons for understanding dynamic material response during failure and, more generally, complexity of earthquake sources.

The prediction incidence of the three most common cancers among Iranian military community during 2007-2019: a time series analysis.

OBJECTIVE: Cancers are one of the most important public health problems in Iran. Because of the importance of cancers, the purpose of the current study was to the prediction of the future incidence of the most common cancers among Iranian military community (MC) by using the time series analysis during 2007 to 2019. METHODS: In the current cross-sectional study, all registered cancers among Iranian MC entered the study. To select the best model of prediction, various methods including autocorrelation function (ACF), partial autocorrelation function (PACF), and Akaike information criterion (AIC) statistics were used. All analysis was performed by using ITSM, stata14, and Excel2010 software. RESULTS: The most prevalent cancers among Iranian MC were breast, prostate, and colon cancers respectively. The time series analysis was shown that the trend of all mentioned cancers in Iranian MC will increase in the coming years. CONCLUSIONS: The trend of most prevalent cancers among Iranian MC was increasing but the different factors like the growth of population size and improving the registration system should be regarded.

New physical approaches to treat cancer stem cells: a review.

Cancer stem cells (CSCs) have been identified as the main center of tumor therapeutic resistance. They are highly resistant against current cancer therapy approaches particularly radiation therapy (RT). Recently, a wide spectrum of physical methods has been proposed to treat CSCs, including high energetic particles, hyperthermia (HT), nanoparticles (NPs) and combination of these approaches. In this review article, the importance and benefits of the physical CSCs therapy methods such as nanomaterial-based heat treatments and particle therapy will be highlighted.

Microscopic Evolution of Laboratory Volcanic Hybrid Earthquakes.

Characterizing the interaction between fluids and microscopic defects is one of the long-standing challenges in understanding a broad range of cracking processes, in part because they are so difficult to study experimentally. We address this issue by reexamining records of emitted acoustic phonon events during rock mechanics experiments under wet and dry conditions. The frequency spectrum of these events provides direct information regarding the state of the system. Such events are typically subdivided into high frequency (HF) and low frequency (LF) events, whereas intermediate "Hybrid" events, have HF onsets followed by LF ringing. At a larger scale in volcanic terranes, hybrid events are used empirically to predict eruptions, but their ambiguous physical origin limits their diagnostic use. By studying acoustic phonon emissions from individual microcracking events we show that the onset of a secondary instability-related to the transition from HF to LF-occurs during the fast equilibration phase of the system, leading to sudden increase of fluid pressure in the process zone. As a result of this squeezing process, a secondary instability akin to the LF event occurs. This mechanism is consistent with observations of hybrid earthquakes.

Observation of the Kibble-Zurek Mechanism in Microscopic Acoustic Crackling Noises.

Characterizing the fast evolution of microstructural defects is key to understanding "crackling" phenomena during the deformation of solid materials. For example, it has been proposed using atomistic simulations of crack propagation in elastic materials that the formation of a nonlinear hyperelastic or plastic zone around moving crack tips controls crack velocity. To date, progress in understanding the physics of this critical zone has been limited due to the lack of data describing the complex physical processes that operate near microscopic crack tips. We show, by analyzing many acoustic emission events during rock deformation experiments, that the signature of this nonlinear zone maps directly to crackling noises. In particular, we characterize a weakening zone that forms near the moving crack tips using functional networks, and we determine the scaling law between the formation of damages (defects) and the traversal rate across the critical point of transition. Moreover, we show that the correlation length near the transition remains effectively frozen. This is the main underlying hypothesis behind the Kibble-Zurek mechanism (KZM) and the obtained power-law scaling verifies the main prediction of KZM.

Reproductive biology of largescale tonguesole Cynoglossus arel in coastal waters of Bandar Abbas, Persian Gulf, Iran.

The objectives of this study were to determine the reproductive cycle of largescale tonguesole Cynoglossus arel, a commercially valuable flatfish species, in coastal waters of Bandar Abbas, along the south coast of Iran in the Persian Gulf. From October 2009 to September 2010, 905 fish were collected in monthly samples, and their length, weight, sex, gonad weight, and maturity status recorded. These data revealed that ovary weight in females is low from July to September, then increases to a peak in February followed by a decrease, indicating that the peak spawning season is from February to March with some spawning lasting until June. Males showed a corresponding seasonal pattern in testis weight, although with much less pronounced seasonal differences than gonad weight in females. Five maturity classes were described based on ovarian and testicular histology, corresponding with macroscopic analysis of gonads. The spawning season in C. arel is prolonged, similar to several other tropical flatfish species, and larger adult females tended to have an even more prolonged spawning period than smaller, presumably younger adult females. Combined, our results indicated that C. arel is a winter-to-spring batch spawner with an asynchronous type of ovarian development.

Faulting of rocks in a three-dimensional stress field by micro-anticracks.

Nucleation and propagation of a shear fault is known to be the result of interaction and coalescence of many microcracks. Yet the character and rate of the microcracks' interactions, and their dependence on the three-dimensional stress state are poorly understood. Here we investigate formation of microcracks during sandstone faulting under 3D-polyaxial stress fields by analyzing multi-stationary acoustic waveforms. We show that in a true three-dimensional stress state (a) faulting forms in a orthorhombic pattern, and (b) the emitted acoustic waveforms from microcracking carry a shorter rapid slip phase. The later is associated with microcracking that dominantly develops parallel to the minimum stress direction. Our results imply that due to inducing the micro-anticracks, the three-dimensional (3D) stress state can quicken dynamic weakening and rupture propagation by a factor of two relatively to simpler stress states. The results suggest a new nucleation mechanism of 3D-faulting with implications for earthquakes' instabilities, as well as the understanding of avalanches associated with dislocations.

SU-D-211-03: An Automated Inverse Planning Optimization Approach for Single- Fraction and Fractionated Radiosurgery Using Gamma Knife Perfexion.

PURPOSE: The purpose of this work is to develop an automated inverse planning approach to generate singe-fraction and fractionated stereotactic radiosurgery (SRS) treatment plans for Gamma Knife Perfexion. METHODS: Our automated approach consists of two steps: 1) a grassfire-based algorithm to carefully determine the isocentre locations; 2) a penalty-based optimization to find the optimal shot shapes and their intensities to minimize the deviation of the delivered dose from the objective dose in all structures. For single-fraction SRS, a margin-less approach was taken: conformity of dose to the gross tumor volume (GTV) with a steep dose fall-off was prioritized. For fractionated radiosurgery, dose homogeneity was given a higher priority since planning target volumes (PTV) were applied to account for daily setup variation, and these PTVs could overlap with organs-at-risk (OARs). The two-step approach was tested on seven clinical cases with PTV sizes of 0.5cm̂3-56.5cm̂3. In the tested cases, the PTV had 0%-38% overlap with OARs. RESULTS: For single-fraction SRS, the dose to 1mm̂3 brainstem was on average 0.24Gy (range: -2.4Gy to +2.0Gy) lower compared to manually-generated plans. Beam-on time varied with the number of isocentres, but on average was 33min longer than manually- generated plans. The optimization algorithm took 215min on average, while isocentre selection performed in <10s.For fractionated SRS, the average PTV coverage was V95=94.9% (range: 92.7%-97.6%) and the mean dose to 1 mm̂3 brainstem was 87.8% of the prescription dose (range: 35.4%- 108.8%). The mean beam-on time per fraction per dose-per-fraction was 4.8min/Gy (range: 0.9min/Gy-10.3min/Gy). We observed a tradeoff between conformity and OARs-sparing in both plans, and added sensitivity to isocentre locations in fractionated plans. In all the cases, GTV received the full prescription dose. CONCLUSIONS: The results indicated that automated inverse planning yields improved conformity and OAR-sparing for single- fraction SRS and is capable of generating homogeneous fractionated SRS. This work is partially funded by Elekta Instrument, AB, Stockholm, Sweden.

Predicting isolated postchallenge hyperglycaemia: a new approach; Tehran Lipid and Glucose Study (TLGS).

AIMS: To determine factors predicting isolated postchallenge hyperglycaemia (IPH) defined as fasting plasma glucose (FPG) < 7.0 mmol/l and 2-h plasma glucose (2-hPG) >or= 11.1 mmol/l after an oral glucose tolerance test (OGTT) and factors influencing the value of 2-hPG in a population-based study. MATERIALS AND METHODS: From 15,005 participants in the Tehran Lipid and Glucose Study (TLGS), we analysed the results of OGTTs in 5386 individuals (2909 women and 2437 men) aged >or= 20 years, free of known diabetes and any other disorders influencing glucose metabolism. Logistic and multiple linear regression models were developed to predict IPH and the 2-hPG, respectively. RESULTS: The overall prevalence of non-diabetic subjects, IPH and undiagnosed Type 2 diabetes mellitus (FPG >or= 7.0 mmol/l) were 94.5% (n = 5088), 2.5% (n = 133) and 3.1% (n = 165), respectively. Of subjects with IPH, 29.3% (n = 39) had FPG levels < 5.6 mmol/l. Factors associated with IPH were FPG (mmol/l) [odds ratio (OR) 11.05, 95% confidence interval (CI) 7.9, 15.4], age >or= 40 years (OR 2.0, 95% CI 1.3, 3.2), abnormal waist circumference (OR 2.1, 95% CI 1.4, 3.1) and serum triglycerides >or= 1.7 mmol/l (OR 2.0, 95% CI 1.3, 3.1). In the multiple linear regression model, six explanatory factors (FPG, age, female sex, triglycerides, systolic blood pressure, waist circumference) were positively related to 2-hPG. CONCLUSIONS: The model could predict 47.7% of total variance of 2-hPG. Based on our results in this Iranian population, OGTT can be recommended in subjects with FPG < 7.0 mmol/l in the presence of abnormal waist circumference and triglycerides, age >or= 40 years and in particular when FPG is close to 7.0 mmol/l.