Object-oriented database management system case study for declarative query language

Object-Oriented database management systems (OODBMS) combine the abstraction power of objects with the query and performance capabilities of database management systems. Existing query notations were missing many object related features until recently. The introduction of a new query notation, known by Object Comprehensions, allows queries to be expressed clearly and processed efficiently. Our work is to establish a testbed for the processing of Object Comprehension Language (OCL) queries using an experimented object-oriented database, Ode. This thesis overviews object-oriented databases evolution, and object query processing, then introduces an object-oriented database system, Ode, whose programming language O\sp{++} is based on C\sp{++}. A university data model is built using O\sp{++}, stored into the Ode database, and utilities, such as bag, list and set, are written to support the processing of OCL queries. The translation of OCL queries into O\sp{++} is not part of this thesis, but is part of a related project

Modeling the visco-hyperelastic–viscoplastic behavior of photodegraded semi-crystalline low-density polyethylene films

In this work we propose to model the mechanical and fracture response of semi-crystalline low-density polyethylene (LDPE) films exposed to accelerated ultraviolet (UV) ageing using a physically based visco-hyperelastic–viscoplastic approach. UV irradiation induces an alteration of the chemical and structural properties of the semi-crystalline polymer, which affects significantly its mechanical behavior. In this work, pristine and oxidized low-density polyethylene films are characterized by conventional physico-chemical and mechanical techniques (FTIR spectroscopy, DSC, HT-GPC, and uniaxial tensile testing). Polyethylene exhibits an oxidation-induced strengthening for a low range of UV radiation doses and a cavitation-induced softening for higher UV radiation doses. A competing multi-scale phenomena induced by UV radiation are incorporated into the constitutive model to capture the macroscopically observed mechanical and fracture behavior. Namely, the model will incorporate at the nano scale, chain scissions and cross-linking and at the meso and macro scales, oxidation-induced cracking, chemi-crystallization, and mechanical damage. The model used the high-temperature gel permeation chromatography-measured molecular weight as degradation indicator. The model was able to capture accurately the evolution of the macroscopically observed mechanical and fracture behavior over a wide range of UV irradiation doses

Mandibular Canine Dimorphism in Establishing Sex Identity in the Lebanese Population

Background and Objective. In forensic investigations, mandibular canines provide excellent materials to identify gender since they are more likely to survive disasters. The objective of this study was to investigate gender dimorphism by comparing the mesiodistal width of mandibular permanent canines and intercanine distance in a group of Lebanese population. Methods. Participants consisted of undergraduate students from the School of Dentistry, Lebanese University, for two academic years who fulfilled the inclusion criteria. Canine widths and intercanine distance were measured by one operator directly on dental casts using a digital caliper. Results. One hundred thirty-three Lebanese dental students (54 males and 69 females) aged 18–25 were included in the study. The intercanine distance was significantly greater in males (P value < 0.0001). The right and the left canine widths were significantly greater in males than in females (P value < 0.0001). However, no significant difference was found between left and right canines for males (P value > 0.05) and females (P value > 0.05). The mean width of canine was greater than 7.188 mm for males. Conclusion. The parameters measured in the present study are of great help in sex identification in forensic investigations in the Lebanese adult population

System Identification of Fused Filament Fabrication Additive Manufacturing Extrusion and Spreading Dynamics

In fused filament fabrication additive manufacturing, polymer extrusion and spreading dynamics affect build quality in both surface finish and mechanical properties. The state of the art in extrusion modeling and control is identification and compensation of a fixed first order pole with a linear model of the system. However, physical nonlinearities cause deviation of this pole in practice. To advance the aim of slicing using accurate nonlinear dynamic models, this work presents a system and procedure for automated measurement of dynamic bead extrusion. The system uses a belt printer, iFactory3D One Pro, with nozzle tilted 45 degrees from the build belt, and a snapshot 3D scanner. Single layer prints in polylactic acid (PLA) are scanned and then automatically ejected. The gcode for the single bead print holds the gantry speed fixed or extrusion speed constant while the extrusion flow rate or gantry speed is varied as a step input signal in space. The experiment design matrix varied two variables: gantry speed and extrusion flow rate. Time constants are fitted to bead area signals that are extracted from the scan data to obtain nonlinear models. Depending on the experiment condition, the percent difference between the highest time constant and the lowest time constant ranged from 279% to 61%, confirming the high nonlinearity of the extrusion system in FFF 3D printers. Additionally, measurements are performed on a cartesian 3D printer with a 2D scanner to test applicability of the methods to a general audience and verify observed trends. It was observed that larger steps in extrusion velocity for a constant X-Axis velocity, yielded smaller time constants, while the same steps in velocity using a constant extrusion velocity condition with variable X-Axis velocity, yielded the opposite trend. Moreover, the time constants for a step up in extrusion velocity yielded higher overall values in time constant when compared to step down conditions.Mechanical Engineerin

Experimental investigation and modeling attempt on the effects of ultraviolet aging on the fatigue behavior of an LDPE semi-crystalline polymer

The objective of this study was to investigate the effect of UV irradiation on the fatigue life of a bulk semi-crystalline polymer. Low-density polyethylene samples exposed to different UV irradiation doses were fatigue tested. Fatigue indicator based on dissipated energy per cycle was found to present the best correlation with the experimental fatigue results. A master curve unifying the experimental fatigue results for as-received and UV-aged materials was obtained when subtracting the dissipated energy threshold from the total dissipated energy. Finally, the evolution of the damage with cyclic loading was analyzed and preliminary modeling was attempted.This research was supported by the Qatar National Research Fund (NPRP grant No. 7-1562-2-571). We would like to acknowledge the fruitful discussions with Profs. Eddine Gherdaoui and Jean-Michel Gloaguen of the University of Lille

New developments in fracture of rubbers: Predictive tools and influence of thermal aging

In this work, the influence of thermal oxidative aging on the ultimate mechanical properties of rubbers is investigated. Two new approaches to predict failure properties are proposed. The first one is the stress limiter approach that uses a “damage” parameter allowing determination of the failure stress and strain of an aged material knowing both the mechanical properties and macromolecular network characteristics of an as-received material. The second one is an extension of the energy limiter approach that suggests capturing the drop of the stress at failure by replacing the strain energy density function of an as-received elastomeric material by a function expressed in terms of an energy limiter. The predictive capabilities of these two approaches are validated using experimental results for two elastomeric materials: an EPDM and a polychloroprene (CR), both of which exhibit a largely predominant post-crosslinking (over chain scissions) during aging. Comparison between the predictions and the experimental results in terms of failure stresses and strains under uniaxial tension showed a good agreement. Consequently, these two approaches are promising tools for designing elastomeric parts subjected to thermal oxidative aging

Neurological disorders in HIV:Hope despite challenges

INTRODUCTION: Human Immunodeficiency virus (HIV) is a virus that causes several diseases by attacking the human immune system. It is transmitted by contact with certain bodily fluids of an infected person, most commonly during unprotected sex, through sharing needles, or from mother to baby during pregnancy, birth or breastfeeding. The central nervous system is not spared from this virus, as HIV has been shown to induce several neurological disorders. However most neurological pathologies (such as dementia, infections, meningitis, and neuropathy) rarely show until late stages, in this case, after the patients develop acquired immunodeficiency syndrome (AIDS). This article aims to review the neurological disorders in the HIV population and the attempts initiated to limit the disease. METHODOLOGY: Data were collected from medical journals published on PubMed, Ovid MEDLINE, Science Direct and Embase bibliographical databases with a predefined search strategy. All articles considering neurological disorders associated with HIV were considered. RESULTS: To date, the pathogenesis of HIV‐associated neurological complications remains poorly elucidated; thus, imposing a hindrance and limitations on the treatment options. Nevertheless, some studies have reported alterations in dendritic spine as the causative agent for developing brain damage. CONCLUSION: HIV remains one of the most serious global health challenges, with neurological manifestations imposing a major concern among patients with HIV. Despite the availability and efficacy of antiretroviral therapies, yet, the risk of developing neurological complications remains relatively high among patients with HIV. Thus, the 2030 HIV vision must focus on further preventive measures to protect HIV patients from developing such neurological complications

All-Cause Mortality in Type 2 Diabetes Patients Hospitalized for COVID-19 and Treated with Corticosteroids: A Single Center Cross-Sectional Study

Objective: This study aims to compare all-cause mortality and other hospital outcomes of hospitalized coronavirusdisease of 2019 patients using corticosteroids. Materials and methods: A comparative cross-sectional study was performed over three months by collecting data from patients’ medical charts. Results: The sample included 129 patients with type 2 diabetes (T2D) and 293 patients without diabetes, with more men than women in both groups. Patients withT2D were older, namely, those aged more than 70 years (54.3%) with the majority having abnormal glucose levels on admission (76.1%) and at discharge (76.9%). As a primary outcome, higher all-cause mortality was reported among patients without diabetes having more than two comorbidities (38.2%) compared to those with two or single comorbidities (21.0% and 13.9% respectively; p = 0.009). It significantly increased if patients without diabetes had abnormal glucose levels at admission (51.7%; p &lt; 0.001) and discharge (44.7%; p &lt; 0.001) compared to those with normal levels. Critical cases had higher all-cause mortality compared to less severe cases in patients with T2D (58.8%; p &lt; 0.001) and without diabetes (61.0%; p &lt; 0.001). Among secondary outcomes, a higher length of stay in the hospital was noted among patients with T2D (8.4 vs. 7.3 days; p = 0.015), in addition to a significantly higher number of ventilator-free days (2.7 vs. 1.6 days; p = 0.039). Conclusions: Although the treatment with corticosteroids was comparable between patients with and without T2D, hospital outcomes varied between the groups. Findings from this study can help provide additional clinical support for patients with T2D to allow better in-hospital management of COVID-19 cases

Benchmarking the Tensile Properties of Polylactic Acid (PLA) Recycled Through Fused Granule Fabrication Additive Manufacturing

To progress toward a circular economy of thermoplastic polymers, the adoption of 3D printers to make functional articles can facilitate distributed recycling. To this end, the mechanical degradation of polymers through multiple recycling cycles must be quantified. This work presents a procedure and benchmark dataset of tensile property degradation for polylactic acid (PLA) feedstock in multiple recycling passes with a fused granule fabrication process. To establish recycling with minimal processing (shredding and sieving), modifications were required to the granule feeding hopper of the 3D printer. Two distinct orientations were chosen to obtain tensile test coupons. These coupons were die-cut from machined 3D printed rectangular cross-section tubes, with one orientation along the bead (0°) and the other perpendicular to it (90°). Tensile properties are presented for 3D printed virgin material and one, two, three, and four passes of recycling. In terms of print orientation, the results indicate that samples pulled at 0° and 90° exhibited similar mechanical properties. However, there was an average decrease of 3.1% in ultimate tensile strength and a 1.7% decrease in elastic modulus for the samples along 90° orientation for all recycling passes. The samples along 0° demonstrated a 13.7% higher strain at fracture compared to those along 90°. Regarding the number of recycling passes, the findings suggest that the mechanical characteristics of PLA remain largely unaffected even after undergoing four recycling cycles. However, when the material is pulled in the direction of the bead, a 3.09% decrease in ultimate tensile strength is observed in the fourth recycling pass. The elastic modulus and strain at fracture did not exhibit a clear trend. It is important to note that the testing results display some variability, which can be attributed to a combination of stochasticity in the printing process and the preparation procedure employed.Mechanical Engineerin

Study of ordered hadron chains with the ATLAS detector

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