A Potential Foundation for Emergent Space-Time

We present a novel derivation of both the Minkowski metric and Lorentz transformations from the consistent quantification of a causally ordered set of events with respect to an embedded observer. Unlike past derivations, which have relied on assumptions such as the existence of a 4-dimensional manifold, symmetries of space-time, or the constant speed of light, we demonstrate that these now familiar mathematics can be derived as the unique means to consistently quantify a network of events. This suggests that space-time need not be physical, but instead the mathematics of space and time emerges as the unique way in which an observer can consistently quantify events and their relationships to one another. The result is a potential foundation for emergent space-time.Comment: The paper was originally titled "The Physics of Events: A Potential Foundation for Emergent Space-Time". We changed the title (and abstract) to be more direct when the paper was accepted for publication at the Journal of Mathematical Physics. 24 pages, 15 figure

Information-Based Physics: An Observer-Centric Foundation

It is generally believed that physical laws, reflecting an inherent order in the universe, are ordained by nature. However, in modern physics the observer plays a central role raising questions about how an observer-centric physics can result in laws apparently worthy of a universal nature-centric physics. Over the last decade, we have found that the consistent apt quantification of algebraic and order-theoretic structures results in calculi that possess constraint equations taking the form of what are often considered to be physical laws. I review recent derivations of the formal relations among relevant variables central to special relativity, probability theory and quantum mechanics in this context by considering a problem where two observers form consistent descriptions of and make optimal inferences about a free particle that simply influences them. I show that this approach to describing such a particle based only on available information leads to the mathematics of relativistic quantum mechanics as well as a description of a free particle that reproduces many of the basic properties of a fermion. The result is an approach to foundational physics where laws derive from both consistent descriptions and optimal information-based inferences made by embedded observers.Comment: To be published in Contemporary Physics. The manuscript consists of 43 pages and 9 Figure

The prognostic value of long noncoding RNA MEG3 expression in the survival of cancer patients: a meta-analysis

Long non-coding RNAs (lncRNAs) play an important role in carcinogenesis and cancer progression. lncRNA MEG3 is a tumor suppressor that is down-regulated in several cancers. However, its prognostic value in human malignancies remains controversial. We have therefore undertaken a meta-analysis to explore the relationship between cancer survival and the expression of long non-coding RNA MEG3. A systematic literature search identified 13 potentially eligible investigations comprising 1733 patients in nine different cancer types. In the pooled analysis, a low expression of MEG3 was associated with a low overall survival (OS) in cancer patients with a combined HR of 0.830 [hazard ratio (HR) =0.83; 95% CI: 0.70–0.98; P=0.0.03; random effect model]. However, sub-group analysis according to cancer type revealed that MEG3 expression was not associated with better OS in gastrointestinal cancer (HR = 0.58, 95% CI = 0.33 to 1.03, P = 0.06) and breast cancer patients (HR = 0.85, 95% CI: 0.12 to 5.88, P = 0.87). In conclusion, our results demonstrate that only in the pooled analysis, there was a significant relationship between MEG3 expression and cancer survival. Further investigation of other molecular biomarkers involved in tumorigenesis-related pathways is necessary

Development of A Head Docking Device for Linac-based Stereotactic Radiosurgery System to be Installed on Neptun 10 PC Linac

Introduction:  Stereotactic  radiosurgery  is  a  technique  for  the  treatment  of  intracranial  lesions  with  highly  collimated  x-ray  beam.  Linac-based  radiosurgery  is  currently  performed  by  two  techniques:  couch or pedestal mounted. In the first technique, a device is required to affix patient's head to a couch  and  moreover  to  translate  it  accurately.  Structure  of  such  a  device  constructed  by  the  authors  in  addition to the acceptance test which was performed to evaluate the device has been described in this  article.  Materials and Methods:  A head docking device has been designed and constructed according to the  geometry of linac's couch and desired functions. The device is completely made from aluminum and  consists  of  four  major  components:  attachment  bar,  lower  structure  with  four  movements,  upper  structure with two movements equipped with a lock, two handles and a mounting ring for stereotactic  frame. Translating accuracy, mechanical stability and isocentric accuracy were assessed in the frame of  acceptance test.  Results:  Translating  accuracy,  mechanical  stability  and  isocentric  accuracy  within  95%  confidence  intervals were found to be 1, 1.64 and 3.2 mm, respectively.  Discussion and Conclusion: According to AAPM report no.54 recommendation head docking device  should translate head with accuracy of 1 mm, the property which was met by the constructed device.  Moreover  considering  the  measured  isocentric  accuracy,  encompassing  mechanical  stability,  constructed device can confidently be used in stereotactic treatment

A Stochastic Operational Planning Model for Smart Power Systems

Smart Grids are result of utilizing novel technologies such as distributed energy resources, and communication technologies in power system to compensate some of its defects. Various power resources provide some benefits for operation domain however, power system operator should use a powerful methodology to manage them. Renewable resources and load add uncertainty to the problem. So, independent system operator should use a stochastic method to manage them. A Stochastic unit commitment is presented in this paper to schedule various power resources such as distributed generation units, conventional thermal generation units, wind and PV farms, and demand response resources. Demand response resources, interruptible loads, distributed generation units, and conventional thermal generation units are used to provide required reserve for compensating stochastic nature of various resources and loads. In the presented model, resources connected to distribution network can participate in wholesale market through aggregators. Moreover, a novel three-program model which can be used by aggregators is presented in this article. Loads and distributed generation can contract with aggregators by these programs. A three-bus test system and the IEEE RTS are used to illustrate usefulness of the presented model. The results show that ISO can manage the system effectively by using this mode

Electrostatic Twisting of Core-Shell Nanofibers for Strain Sensing Applications

Stretchable strain sensors are increasingly needed in emerging fields of wearable electronics and smart textiles for applications ranging from human motion detection to health monitoring. Nanofibers made from conductive materials or composites of polymers and conductive nanoparticles exhibit strong sensitivities but are difficult to utilize due to their small dimensions. Herein, we report on a technique for producing core-shell nanofibers and in-situ twisting of them to each other using a rotating electric field. The process produces sensitive threads that can be handled easily and used, for instance, in smart textile applications. The core-shell nanofibers utilized poly(vinylidene fluoride) as the structural polymer and multiwalled carbon nanotubes were used to make the core electrically conductive. The structure of nanofibers was studied through a set of analytical methods. The fibers exhibit strong piezoresistive responses and can be utilized in various strain sensing applications. Mechanical properties of fabricated submicron fiber yarns are compared with non-twisted fibers and improvement of their stretchability has been demonstrated. Furthermore, the sensitivity of fiber threads to different directions of stretching depended on the way of their knitting into fabric has been compared

Noise Pollution and Traffic Noise Index on Mashhad Main Streets during the Busiest Hours of Summer

Introduction: Among the environmental pollutions, noise is very important for its physiological  and psychological effects on human. Traffic noise is one of the most important pollutants and the  hospitals  are  one  of  the  critical  places  regarding  this  type  of  noise.  For  these  reasons,  in  the  summer  of  1382,  the  traffic  noise  of  Mashhad  main  streets  around  the  hospitals  was  assessed  during the busiest hours.  Materials and Methods: The noise indexes such as L Aeq , L Afmax , L 10 , L 50  and L 90  were measured  by a Sound-Level-Meter, model Investigator 2260. The traffic load was also determined. On the  basis  of  these  results,  Noise  Pollution  Level  (NPL)  and  Traffic  Noise  Index  (TNI)  were  calculated. The assessment was done during three different periods of the days in twelve stations.   Results: Based on the obtained results, the maximum L Aeq  was recorded on Bahar Street during  the morning hours and on Koohsangi Street during the noon and night periods. Throughout the  three  periods  the  maximum  NPL  and  TNI  were  estimated  on  Bahar  and  Nakhrisi  Streets,  respectively.  The  correlation  between  all  of  the  indexes  was  analyzed  and  a  logarithmic  correlation was observed between L Aeq  and the traffic load.   Discussion  and  Conclusion:  On  the  basis  of  the  noise  standard  in  free  field  in  Iran,  noise  pollution is a serious problem in Mashhad

A Monte Carlo Simulation of Photon Beam Generated by a Linear Accelerator

ntroduction:  Monte  Carlo  simulation  is  the  most  accurate  method  of  simulating  radiation  transport  and  predicting doses at different points of interest in radiotherapy. A great advantage of the Monte Carlo method  compared  to  the  deterministic  methods  is  the  ability  to  deal  accurately  with  any  complex  geometry.  Its  disadvantage is the extremely long computing time required to obtain a dose distribution with good statistical  accuracy.  Materials and Methods: The MCNP-4C Monte Carlo code was used to simulate a 9 MV photon beam from  a Neptun 10PC linear accelerator. The accelerator was modeled as a complete unit consisting of a target, exit  window, initial collimator, primary collimator, flattening filter, monitor chamber and secondary collimator.  The geometrical details and the composition of each component was either obtained from the manufacturer or  was  directly  measured.  The  simulation  of  the  source  was  performed  in  a  two  step  process.  Initially,  the  electron source was defined. Secondly, the bremsstrahlung energy spectra and the fluence distribution at the  scoring  planes  were  used  to  define  the  photon  source.  The  simulated  electron  beam  energy  followed  a  Gaussian distribution, with FWHM equal to 12% in nominal energy. The used intensity distribution of the  electron beam also followed a Gaussian distribution with a FWHM equal to 0.34 cm. To compute the photon  beam data a 50 × 50 × 40 cm 3  water phantom located at SSD = 100 cm was simulated. The depth dose and  the dose profile curves were calculated for four different field sizes (5×5, 10×10, 20×20 and 30×30 cm 2 ) and  compared against the measured values. The low-energy cut-off for the photons and electrons was 10 and 500  KeV, respectively. The measurements were carried out by using a Scanditronix dose scanning system and a  0.12 cm 3  RK ionization chamber.  Results: To verify the simulated model, the calculated Monte Carlo dose data were compared against the  corresponding measured values. The energy spectra and the angular distribution of the x-ray beam generated  by the Neptun 10PC linac was examined. The result showed an efficiency of about 73% for the production of  bermsstrahlung photon by the target. The agreement between the calculated and the measured depth dose and  the dose profile was generally better than 2% for all the fields.  Discussion and Conclusion: The simulation of the Neptun 10PC linac performed in this work is capable of  computing the depth dose data and the beam profiles in water phantom for all the predefined fields including  5×5, 10×10, 20×20 and 30×30 cm 2 . Therefore, it can be concluded that MCNP-4C is a suitable tool for the  dose calculation in radiotherapy. The simulated linac machine and the resulting data can be used to predict  the dose distribution in all complex fields

Evaluation of Reliability Parameters in Micro-grid

Evaluation of the reliability parameters in micro-grids based on renewable energy sources is one of the main problems that are investigated in this paper. Renewable energy sources such as solar and wind energy, battery as an energy storage system and fuel cell as a backup system are used to provide power to the electrical loads of the micro-grid. Loads in the micro-grid consist of interruptible and uninterruptible loads. In addition to the reliability parameters, Forced Outage Rate of each component and also uncertainty of wind power, PV power and demand are considered for micro-grid. In this paper, the problem is formulated as a nonlinear integer minimization problem which minimizes the sum of the total capital, operational, maintenance and replacement cost of DERs. This paper proposes PSO for solving this minimization problem

Therapeutic potential of A2 adenosine receptor pharmacological regulators in the treatment of cardiovascular diseases, recent progress, and prospective

Adenosine and its analogs are of particular interest as potential therapeutic agents for treatment of cardiovascular diseases (CVDs). A2 adenosine receptor subtypes (A2a and A2b) are extensively expressed in cardiovascular system, and modulation of these receptors using A2 adenosine receptor agonists or antagonists regulates heart rate, blood pressure, heart rate variability, and cardiovascular toxicity during both normoxia and hypoxia conditions. Regulation of A2 adenosine receptor signaling via specific and novel pharmacological regulators is a potentially novel therapeutic approach for a better understanding and hence a better management of CVDs. This review summarizes the role of pharmacological A2 adenosine receptor regulators in the pathogenesis of CVDs. © 2018 Wiley Periodicals, Inc