Improved Balanced Flow Computation Using Parametric Flow

We present a new algorithm for computing balanced flows in equality networks arising in market equilibrium computations. The current best time bound for computing balanced flows in such networks requires $O(n)$ maxflow computations, where $n$ is the number of nodes in the network [Devanur et al. 2008]. Our algorithm requires only a single parametric flow computation. The best algorithm for computing parametric flows [Gallo et al. 1989] is only by a logarithmic factor slower than the best algorithms for computing maxflows. Hence, the running time of the algorithms in [Devanur et al. 2008] and [Duan and Mehlhorn 2015] for computing market equilibria in linear Fisher and Arrow-Debreu markets improve by almost a factor of $n$

Eventual Stability of pure polynomials over the rational field

A polynomial with rational coefficients is said to be pure with respect to a rational prime $p$ if its Newton polygon has one slope. In this article, we prove that the number of irreducible factors of the $n$-th iterate of a pure polynomial over the rational field $\mathbb Q$ is bounded independent of $n$. In other words, we show that pure polynomials are {\em eventually stable}. Consequently, several eventual stability results available in literature follow; including the eventual stability of the polynomial $x^d+c\in\mathbb{Q}[x]$, where $c\ne 0,1$, is not a reciprocal of an integer. In addition, we establish the dynamical irreducibility, i.e., the irreducibility of all iterates, of a subfamily of pure polynomials, namely Dumas polynomials with respect to a rational prime $p$ under a mild condition on the degree. This provides iterative techniques to produce irreducible polynomials in $\mathbb{Q}[x]$ by composing pure polynomials of different degrees. During the course of this work, we characterize all polynomials whose degrees are large enough that are not pure, yet they possess pure iterates. This implies the existence of polynomials whose shifts are all dynamically irreducible in $\mathbb{Z}[x]$

A Time-Space Tradeoff for Triangulations of Points in the Plane

In this paper, we consider time-space trade-offs for reporting a triangulation of points in the plane. The goal is to minimize the amount of working space while keeping the total running time small. We present the first multi-pass algorithm on the problem that returns the edges of a triangulation with their adjacency information. This even improves the previously best known random-access algorithm

Investigation of timepix radiation detector for autoradiography and microdosimetry in targeted alpha therapy

The Timepix detector developed by CERN is a novel and sophisticated particle detector. It consists of a semiconductor layer divided into an array of pixels. This array of pixels is bumpbonded to an electronics integrated layer (i.e. the readout chip). Timepix can be used for a wide range of measurements of electromagnetic radiation and particles and their applications in different fields such as space physics, nuclear physics, radiotherapy physics, imaging and radiation protection. The Timepix detector used in this work was purchased from Amsterdam Scientific Instruments, the Netherlands, in order to investigate its use for microdosimetry purposes, in particular in targeted alpha therapy. The device has the following properties: 256 x 256 pixels of 55 x 55 μm2 area each, the chip is effective for positive or negative charge and can be used to detect electrons, X-rays, neutrons and heavy charge particles. It can work as an energy spectrometer, has good spatial resolution and reason1ble detection efficiency. The device can operate in three common modes: Timepix mode, Medipix mode, and Time-Over-Threshold (TOT) mode. Targeted alpha therapy (TAT) is a novel type of radionuclide therapy in which an alpha emitting radioisotope is attached to a cancer cell seeking vector (so called radioimmunoconjugate (RIC)). Once attached to a cancer cell, it causes localized damage due to traversal and energy deposition high LET a-particles. There is, however, a lack of data related to a-particle distribution in TAT. These data are required to more accurately estimate the absorbed dose on a cellular level. As a result, this work aims to develop a microdosimetry technique, using Timepix detector that will estimate, or better yet determine the absorbed dose deposited by a-particles in cells as well as will measure the biodistribution of the radioisotope in a tumour. Initially, extensive Timepix characterization and testing has been done to evaluate the detector's response, including linearity, reproducibility, and sensitivity to low doses of radiations (μGy-mGy dose region) and energy dependence. 1-125 seeds and superficial X-rays (below 70 kVp), produced by the Gulmay superficial X-ray unit, were used. The measured Timepix pixel value was correlated with the known dose (based on the irradiation time used and TLD-100 measurements) and a pixel-value-to- dose calibration curve was obtained. It was confinned that Timepix value increased linearly with the dose delivered. The dose calibration curves using the superficial X-ray beams showed that the pixel value, however, depended on the energy of the X-ray beam. The application of Timepix to measure radioisotope biodistribution (i.e. autoradiography) was investigated. Mice with Lewis lung (LL2) tumours were treated with about 18 kBq oP27Thlabelled DAB4 murine monoclonal antibody that bounds to necrotic tumour cells. The rationale is to develop a-particle-mediated bystander kill of nearby viable tumour cells. To generate more necrotic tumour cells for 227Th-DAB4 binding, some mice also received chemotherapy before being injected with Th-227-DAB4. Finally, 5 mm tumour sections were cut from treated mice for autoradiography with Timepix. Each tumour section was mounted onto a slide with front face uncovered to allow emission of a-particles from the tumour section. Simple steel collimator (I cm radius, 2 cm length) was manufactured in-house and positioned around the tumour section. The slide was placed 2 cm away from the Timepix detector. Bias voltage of 7 V was applied, and a-particle filter was selected for acquisition. Detector cover was removed, exposing the Si layer, to allow the emitted a-particles ( - 6 Me V) to reach the detector. Image acquisition took -14 h. Good resolution autoradiographs of radiolabelled tumour sections were acquired, showing a-particle, electron and X-ray tracks. Timepix measurements also showed an increased Th-227-DAB4 uptake following chemotherapy due to increase in necrotic tissue volume. Timepix was also used to measure the uptake of Cr-51 by A549 cells (lung carcinoma cell line) for different pH levels and the dependence of uptake on pH was investigated. Timepix was observed to be sensitive to detect small changes in the activity/uptake of radioactive sources depending on the environmental condition and the number of cells. The last part of this thesis deals with the development of a transmitted a-particle microdosimetry technique. First, A549 cells were grown in vitro using standard protocols and were irradiated using a 6 MY photon beam with different doses varying between 2-8 Gy and Ra-226 source was used for a-particle irradiation to evaluate A549 radiation sensitivity using clonogenic assay and MTT assay. The cell line was found radiosensitive, with 050 of~ 2 Gy for X-ray irradiation. For transmitted dosimetry, A549 cells were either unirradiated (control) or irradiated for ~2, 1, 2 or 3 hours with a-particles emitted from a Ra-223 source positioned below a monolayer of A549 cells. The HTS Transwell" 96 well system (Corning, USA), consisting of 2 compartments, was used to develop a method for tracking a-particles through a cell mono layer. This system comprises of two compartments, with liquid Ra-223 evaporated in the lower compartment to avoid a-particle self-absorption inside the liquid. The measured activity of 5 kBq was unifonnly distributed, as confirmed by Timepix detector. The second compartment consists of a flat bottom polycarbonate membrane (I 0 μm thick) where cells are plated. It is sufficiently thin to allow a-particles to penetrate through and hit the cells. Fifteen thousand A549 cells were seeded in the upper compartment that was then inserted into the lower compartment containing the evaporated Ra-223. The transwell system was positioned under the Timepix detector. Transmitted a-particles were detected for 1;2, I, 2 or 3 hour irradiation times. Additionally, DNA double strand breaks (DSBs) in the form of y-H2AX foci, were examined by fluorescence microscopy. The number of transmitted a-particles was correlated with the observed DNA DSBs and the delivered radiation dose was estimated. Additionally, the dose deposited was calculated using Monte Carlo code SRIM. Approximately 20% of a-particles were transmitted and detected by Timepix. The frequency and number of y-H2AX foci increased significantly following a-particle irradiation as compared to unirradiated controls. The RBE equivalent dose delivered to A549 cells was estimated to be approximately 0.66 Gy, 1.32 Gy, 2.53 Gy and 3. 96 Gy after Y2, I, 2 and 3 h irradiation, respectively, considering a relative biological effectiveness of a-particles of 5.5. In summary, the Timepix detector can be used effectively for autoradiography in TAT, providing high resolution images and excellent spatial resolution of detected a-particles, as well as a transmitted a-particle microdosimetry detector. If cross-calibrated using biological dosimetry, this method will give a good indication of the biological effects of a-particles without the need for repeated biological dosimetry which is costly, time consuming and not readily available.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Physical Sciences, 2017

Russian-Egyptian Cooperation in the Context of the Prospects for the Great Eurasian Partnership

The article examines the development of economic cooperation and trade exchange between Russia and Egypt over the past ten years. The most important joint projects of Russia and Egypt at the level of the public and private sectors, as well as the most important obstacles to expanding the scope of economic cooperation and trade exchange at the private sector level between the Egyptian and Russian parties are analyzed.Aim. This study aims to monitor the various forms of economic cooperation between Egypt and Russia, since the history of these relations goes back more tha n two centuries, and currently Russia is considered one of the strongest economies in the world, one of the ten strongest economies in the world, according to the latest report from the International Monetary Fund, and is also the strongest economy in the Eurasian Union.Tasks. Analysis of the most important economic projects in various sectors such as the agriculture and food sector, transport, free zones, energy and military cooperation, tourism between Egypt and the Russian Federation in the period from 2014 to the present, determining the degree of effectiveness of these joint projects and factors contributing to increase in the efficiency of the efficiency of the implementation of these projects and increase economic feasibility. Explore cross-culture barriers that hinder the establishment of closer contacts between the private businesses of both sides.Methods. In this work, using the methods of logical and statistical analysis, factors were identified that contribute to the effectiveness of economic and investment interaction used in the implementation of projects aimed at bilateral development at the state level. The problems arising at the level of interaction between the private sectors of the economy of both countries were also noted.Results. The study showed that economic projects between Egypt and the Russian Federation at the governmental level (governments, agencies, companies and public institutions) can still be considered essential for the Egyptian economy in order to achieve sustainable development, to which it aspires, but, on the contrary, for the private sector it is s till unsatisfactory and very small due to a group of intercultural obstacles, which, in our opinion, are not difficult to overcome.Conclusions. It is advisable to consider aspects of cooperation between Egypt and Russia on a wider and more comprehensive scale than at present, and to use the opportunities available at the level of the public sector on a wider scale. With regard to trade cooperation at the private sector level, it is necessary to develop a plan to increase the volume of trade between the two countries, and it would be useful to enlist the support of the government authorities of the EEA countries

Solving Hammerstein Type Integral Equation by New Discrete Adomian Decomposition Methods

New discrete Adomian decomposition methods are presented by using some identified Clenshaw-Curtis quadrature rules. We investigate two mixed quadrature rules one of precision five and the other of precision seven. The first rule is formed by using the Fejér second rule of precision three and Simpson rule of precision three, while the second rule is formed by using the Fejér second rule of precision five and the Boole rule of precision five. Our methods were applied to a nonlinear integral equation of the Hammerstein type and some examples are given to illustrate the validity of our methods

Collision avoidance system with obstacles and humans to collaborative robots arms based on RGB-D data

The collaboration between humans and machines, where humans can share the same work environment without safety equipment due to the collision avoidance characteristic is one of the research topics for the Industry 4.0. This work proposes a system that acquires the space of the environment through an RGB-Depth sensor, verifies the free spaces in the created Point Cloud and executes the trajectory of the collaborative manipulator avoiding collisions. It is demonstrated a simulated environment before the system in real situations, in which the movements of pick-and-place tasks are defined, diverting from virtual obstacles with the RGB-Depth sensor. It is possible to apply this system in real situations with obstacles and humans, due to the results obtained in the simulation. The basic structure of the system is supported by the ROS software, in particular, the Movelt! and Rviz. These tools serve both for simulations and for real applications. The obtained results allow to validate the system using the algorithms PRM and RRT, chosen for being commonly used in the field of robot path planning.This work has been partially funded by Junta de Castilla y León and FEDER funds, under Research Grant No. LE028P17 and by "Ministerio de Ciencia, Innovación y Universidades" of the Kingdom of Spain through grant RTI2018-100683- B-I00.info:eu-repo/semantics/publishedVersio

Restoration of an AFM Height Image using a Deflection Image at Different Scanning Speeds

The principle of the Atomic Force Microscope involves scanning an object using a probing tip that is mounted on the free end of a micro mechanical cantilever. While the sample is scanned horizontally the cantilever deflects. The deflection of the cantilever can be sensed among several methods. For instance, optical beam deflection where this method is often used because of it’s simplicity. While the scanning process of the sample stage, the detected deflection is compared with the set point deflection. Then, the error signal which is the difference between the detected and set point deflection is minimized by moving the sample stage in the Z – direction. At a set point value this closed –loop feedback operation can maintain the cantilever deflection and hence the tip – sample interaction force. The sample surface is approximately traced by the resulting 3D movement of the sample stage. Therefore, usually the topographic image can be formed from the electrical signals which are used to drive the sample stage scanner in the Z- direction. In this paper, the AFM topographic image is constructed using values obtained by summing the height image that is used for driving the Z- scanner and the deflection image with a weight function that is close to 3. The value of has been determined experimentally using trail and error. This method gives more faithful topographic image

Genomic epidemiology of the first epidemic wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Palestine.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for the COVID-19 pandemic, continues to cause a significant public-health burden and disruption globally. Genomic epidemiology approaches point to most countries in the world having experienced many independent introductions of SARS-CoV-2 during the early stages of the pandemic. However, this situation may change with local lockdown policies and restrictions on travel, leading to the emergence of more geographically structured viral populations and lineages transmitting locally. Here, we report the first SARS-CoV-2 genomes from Palestine sampled from early March 2020, when the first cases were observed, through to August of 2020. SARS-CoV-2 genomes from Palestine fall across the diversity of the global phylogeny, consistent with at least nine independent introductions into the region. We identify one locally predominant lineage in circulation represented by 50 Palestinian SARS-CoV-2, grouping with genomes generated from Israel and the UK. We estimate the age of introduction of this lineage to 05/02/2020 (16/01/2020-19/02/2020), suggesting SARS-CoV-2 was already in circulation in Palestine predating its first detection in Bethlehem in early March. Our work highlights the value of ongoing genomic surveillance and monitoring to reconstruct the epidemiology of COVID-19 at both local and global scales