Rehearsal: A Configuration Verification Tool for Puppet

Large-scale data centers and cloud computing have turned system configuration into a challenging problem. Several widely-publicized outages have been blamed not on software bugs, but on configuration bugs. To cope, thousands of organizations use system configuration languages to manage their computing infrastructure. Of these, Puppet is the most widely used with thousands of paying customers and many more open-source users. The heart of Puppet is a domain-specific language that describes the state of a system. Puppet already performs some basic static checks, but they only prevent a narrow range of errors. Furthermore, testing is ineffective because many errors are only triggered under specific machine states that are difficult to predict and reproduce. With several examples, we show that a key problem with Puppet is that configurations can be non-deterministic. This paper presents Rehearsal, a verification tool for Puppet configurations. Rehearsal implements a sound, complete, and scalable determinacy analysis for Puppet. To develop it, we (1) present a formal semantics for Puppet, (2) use several analyses to shrink our models to a tractable size, and (3) frame determinism-checking as decidable formulas for an SMT solver. Rehearsal then leverages the determinacy analysis to check other important properties, such as idempotency. Finally, we apply Rehearsal to several real-world Puppet configurations.Comment: In proceedings of ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI) 201

Modeling and simulation of polycrystalline ZnO thin-film transistors

Thin film transistors (TFTs) made of transparent channel semiconductors such as ZnO are of great technological importance, because their insensitivity to visible light makes device structures simple. In fact, several demonstrations are made on ZnO TFT achieving reasonably good field effect mobilities of 1-10 cm2/Vs, but reveal insufficient device performances probably due to the presence of dense grain boundaries. We have modeled grain boundaries in ZnO thin film transistors (TFTs) and performed device simulation using a two-dimensional device simulator for understanding the grain boundary effects on the device performance. Actual polycrystalline ZnO TFT modeling is commenced with considering a single grain boundary in the middle of the TFT channel formulating with a Gaussian defect distribution localized in the grain boundary. A double Shottky barrier is formed in the grain boundary and its barrier height are analyzed as functions of defect density and gate bias. The simulation is extended to the TFTs with many grain boundaries to quantitatively analyze the potential profiles developed along the channel. One of the big contrasts of polycrystalline ZnO TFT compared with a polycrystalline Si TFT is that much smaller nanoscaled grain size induces heavy overlap of double Shottky barriers. Through the simulation, we can estimate the total trap state density localized in the grain boundaries for a polycrystalline ZnO by knowing apparent mobility and grain size in the device.Comment: Submitted to Journal of Applied Physic

Photolumniscence/Fluorescence Spectroscopic Technique for Nanomaterials Characterizations

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Patients' experiences of urinary catheterization and living with urinary catheter : a literature review

SAMMANFATTNING  Bakgrund  Kateterisering av urinblåsan är en vanligt förekommande behandlingsåtgärd inom hälso- och sjukvården som kan vara indicerad vid exempelvis urinretention och residualurin efter miktion. Kateterisering kan orsaka komplikationer, såsom urinvägsinfektioner och urinläckage, vilket kan medföra lidande. Sjuksköterskan har som uppgift att lindra lidande genom bland annat personcentrerad och säker vård. Att förstå hur kateterisering kan påverka den individ som är i behov av den är därför viktigt för sjuksköterskans yrkesutövande.  Syfte  Syftet var att beskriva patienters upplevelser relaterade till kateterisering och att leva med urinkateter.  Metod  En icke systematisk litteraturöversikt genomfördes och baserades på 16 vetenskapliga artiklar av kvalitativ och kvantitativ design. Inkluderade artiklar söktes fram i databaserna PubMed och CINAHL med hjälp av lämpliga sökord. Med Sophiahemmet högskolas bedömningsunderlag kvalitetsgranskades inkluderade artiklar och sedan analyserades innehållet för att sammanställas i tre övergripande kategorier; ‘En vardag med urinkateter’, ‘livskvalitet’ och ‘patientens relation till hälso- och sjukvården’.  Resultat  De övergripande kategorierna är indelade i sju underkategorier där patienters upplevelser relaterat till kateterisering av urinvägarna beskrivs. Komplikationer som urinvägsinfektion, urinläckage och trycksår; bristande bemötande och förhållningssätt hos sjuksköterskan; svårigheter i vardagen; informationsbrist samt påverkan på sexuell aktivitet är aspekter som kan påverka upplevelsen enligt patienter.  Slutsats  Föreliggande litteraturöversikt beskriver hur olika faktorer påverkar upplevelsen av kateterisering och att leva med urinkateter samt vad de olika metoderna för kateterisering har för betydelse i upplevelsen. Faktorer såsom komplikationer med smärta, urinläckage och urinvägsinfektioner; förändrad självbild och påverkad sexuell aktivitet; bristande information och bemötande från vårdgivare samt skattad livskvalitet hade betydelse för patientens upplevelse och eventuella lidande. Utifrån dessa upplevelser kan hälso- och sjukvård identifiera bristfälligt handhavande med personer och medicintekniska vårdmoment samt initiera förbättringsarbete i syfte att stärka patienters upplevda livskvalitet relaterat till urinkateterisering. ABSTRACT  Background  Urinary catheterization is a common treatment in health care and there are several reasons why catheter is indicated. It is often due to urinary retention and residual urine volume after urination. Urinary catheterization can cause complications, such as urinary tract infections and leakage, which can cause suffering. The nurse's task is to relieve suffering through, among other things, person-centered and safe care. Understanding how catheterization can affect the individuals who are in need of it, and it is therefore important for the nurses’ professional practice.  Aim  The aim of this study was to describe patients experiences related to urinary catheterization and living with urinary catheter.  Method  A non-systematic literature review was conducted and based on 16 scientific articles, with both qualitative and quantitative design. Included articles were searched in the databases PubMed and CINAHL using appropriate keywords. With the Sophiahemmet university's quality framework the articles were quality examined and then the content was analyzed to be grouped into three general categories; 'A daily life with a urinary catheter', 'quality of life' and 'the patient's relationship to health care'.  Results  The general categories are divided into seven subcategories where patients' experiences related to catheterization of the urinary tract are described. Complications such as urinary tract infection, urinary leakage and pressure ulcers; the deficient conduct and approach of nurses; difficulties in everyday life; Lack of information and influence on sexual activity are aspects that can affect the experience according to patients.  Conclusions  This literature review describes how various factors affect the experience of catheterization and living with urinary catheters, and what the different methods of catheterization have for the impact on the experience. Factors such as complications with pain, urinary leakage and urinary tract infections; altered self-image and affected sexual activity; lack of information and response from caregivers as well as estimated quality of life had significance for the patient’s experience and possible suffering. With these experiences, health care can identify inadequate handling with persons and medical devices, and initiate improvement work with the aim of strengthening the patients’ perceived quality of life related to urinary catheterization.