Bounds on Slow Roll at the Boundary of the Landscape

We present strong evidence that the tree level slow roll bounds of arXiv:1807.05193 and arXiv:1810.05506 are valid, even when the tachyon has overlap with the volume of the cycle wrapped by the orientifold. This extends our previous results in the volume-dilaton subspace to a semi-universal modulus. Emboldened by this and other observations, we investigate what it means to have a bound on (generalized) slow roll in a multi-field landscape. We argue that for $any$ point $\phi_0$ in an $N$-dimensional field space with $V(\phi_0) > 0$, there exists a path of monotonically decreasing potential energy to a point $\phi_1$ within a path length $\lesssim {\cal O}(1)$, such that $\sqrt{N}\ln \frac{V(\phi_1)}{V(\phi_0)} \lesssim - {\cal O} (1)$. The previous de Sitter swampland bounds are specific ways to realize this stringent non-local constraint on field space, but we show that it also incorporates (for example) the scenario where both slow roll parameters are intermediate-valued and the Universe undergoes a small number of e-folds, as in the Type IIA set up of arXiv:1310.8300. Our observations are in the context of tree level constructions, so we take the conservative viewpoint that it is a characterization of the classical "boundary" of the string landscape. To emphasize this, we argue that these bounds can be viewed as a type of Dine-Seiberg statement.Comment: v4: one more referenc

Adaptive sparse Galerkin methods for vibrating continuous structures

Adaptive reduced-order methods are explored for simulating continuous vibrating structures. The Galerkin method is used to convert the governing partial differential equation (PDE)into a finite-dimensional system of ordinary differential equations (ODEs) whose solution approximates that of the original PDE. Sparse projections of the approximate ODE solution are then found at each integration time step by applying either the least absolute shrinkage and selection operator (lasso) or the optimal subset selection method. We apply the two projection schemes to the simulation of a vibrating Euler–Bernoulli beam subjected to nonlinear unilateral and bilateral spring forces. The subset selection approach is found to be superior for this application, as it generates a solution with similar sparsity but substantially lower error than the lasso

Secure SDN Traffic based on Machine Learning Classifier

Nowadays, the majority of human activities are carried out utilizing a variety of services or applications that rely on the local and Internet connectivity services provided by private or public networks. With the developments in Machine Learning and Software Defined Networking, traffic classification has become an essential study subject.  As a consequence of the segregation of control and data planes, Software Defined Networks have some security flaws. To cope with malicious code in SDN, certain operational security techniques have been devised. In this paper, a machine learning model, supervised, was utilized to identify normal and malicious traffic flows. While, normal traffic were generated using Internet traffic generator, malicious traffic were accomplish by Scapy and Python. The main network features of the OpenFlow flow table such as Packets count, bytes counts, packet rates, byte rate for forward and revers flows, were extracted. The combination of good ML classifier and dataset produced the greatest accuracy rate over 99% in DDoS attack detection, according to the results. Further to the main aim, the presented approach could be utilized to classify different traffic flows with the purpose of balance and priorities the important traffic

Text Multilevel Encryption Using New Key Exchange Protocol

رافق التطور التكنولوجي في مجال المعلومات والاتصالات ظهور تحديات أمنية تتعلق بنقل المعلومات. التشفير هو حل جيد. عملية التشفير هي إحدى الطرق التقليدية لحماية النص العادي، وذلك بتحويلها الى صيغ غير مفهومة. التشفير من الممكن ان ينفذ باستخدام تقنيات التعويض، تقنيات التحويل، او العمليات الرياضية. اقترحت هذه الورقة طريقة تتكون من فرعين لتشفير النص. الفرع الأول هو نموذج رياضي جديد لانشاء وتبادل المفاتيح، طريقة تبادل المفاتيح المقترحة هي تطوير لطريقة دايف-هلمن. وهو نموذج لعمليات رياضية جديدة لتبادل المفاتيح بالاعتماد على الاعداد الأولية وإمكانية استخدام الأرقام الصحيحة. بينما الفرع الثاني لهذا المقترح هو خوارزمية تشفير متعددة المفاتيح. توفر الخوارزمية الحالية القدرة على استخدام اكثر من مفتاحين. من الممكن ان تكون المفاتيح أي نوع من الأرقام الصحيحة (على الأقل المفتاح الأخير يكون رقم اولي)، وليس بالضرورة ان تكون المفاتيح بنفس الطول. تعتمد عملية التشفير على تحويل احرف النصوص الى ارقام صحيحة مقترحة، ويتم تحويل هذه الأرقام الى ارقام أخرى باستخدام نموذج رياضي متعدد المستويات عدد من المرات (عدد المستويات يعتمد على عدد المفاتيح المستخدمة)، في حين ان عملية كسر التشفير هي عملية من مستوى واحد يستخدم فيها مفتاح واحد كمفتاح رئيس، بينما المفاتيح الأخرى تستخدم كمفاتيح ثانوية. يتم تغير قيم الرسالة قبل عملية التشفير (من الممكن باستخدام شفرة الاسكي او استخدام نظام مقترح). من الممكن ان تستخدم الخوارزمية المقترحة عدد غير محدود من المفاتيح ذات حجوم كبيرة جدا (اكثر من 7500 بايت)، وعلى الأقل واحد من هذه المفاتيح يكون عدد اولي. يستخدم الاس أيضا للمفاتيح لزيادة التعقيد.The technological development in the field of information and communication has been accompanied by the emergence of security challenges related to the transmission of information. Encryption is a good solution. An encryption process is one of the traditional methods to protect the plain text, by converting it into inarticulate form. Encryption implemented can be occurred by using some substitute techniques, shifting techniques, or mathematical operations. This paper proposed a method with two branches to encrypt text. The first branch is a new mathematical model to create and exchange keys, the proposed key exchange method is the development of Diffie-Hellman. It is a new mathematical operations model to exchange keys based on prime numbers and the possibility of using integer numbers. While the second branch of the proposal is the multi-key encryption algorithm. The current algorithm provides the ability to use more than two keys. Keys can be any kind of integer number (at least the last key is a prime number), not necessarily to be of the same length. The Encryption process is based on converting the text characters to suggested integer numbers, and these numbers are converted to other numbers by using a multilevel mathematical model many times (a multilevel process depending on the number of keys used), while the decryption process is a one-level process using just one key as the main key, while the other keys used as secondary keys. The messages are encoded before encryption (coded by ASCII or any suggested system). The algorithm can use an unlimited number of keys with a very large size (more than 7500 bytes), at least one of them a prime number. Exponentiation is also used for keys to increase complexity. The experiments proved the robustness of the key exchange protocol and the encryption algorithm in addition to the security. Comparing the suggested method with other methods ensures that the suggested method is more secure and flexible and easy to implement

Perceptions of hookah smoking harmfulness: predictors and characteristics among current hookah users

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Securing medical records based on inter-planetary file system and blockchain

In general, health records include important information like the patient’s history, findings of examinations and assessments, diagnosis reports, documentation of consent, and treatment plans. Sharing this information has grown to be a challenge concerning data security, as it could result in compromising patient privacy. Therefore, the patient's information should not be misused or tampered with. In this paper, a full process of storing and retrieving medical records is proposed using a decentralized system through the integration of two emerging technologies: Blockchain and Inter-Planetary File System (IPFS). The system provides solutions for the major security concerns associated with medical files, including authentication and authorization, database breaches, data integrity of local and cloud storage, and data availability. The obtained results indicate a high level of safety by adding security layers such as confidentiality, authentication, authorization and access control, based on different factors. All these aspects contribute to reaching the aim of the proposed system, which is storing and retrieving medical records in a decentralized and safe manner

Introduction to Security for Computer Architecture Students

Supplementary material for a graduate computer architecture class (4824) at Columbia