Understanding software development: Processes, organisations and technologies

Our primary goal is to understand what people do when they develop software and how long it takes them to do it. To get a proper perspective on software development processes we must study them in their context — that is, in their organizational and technological context. An extremely important means of gaining the needed understanding and perspective is to measure what goes on. Time and motion studies constitute a proven approach to understanding and improving any engineering processes. We believe software processes are no different in this respect; however, the fact that software development yields a collaborative intellectual, as opposed to physical, output calls for careful and creative measurement techniques. In attempting to answer the question "what do people do in software development? " we have experimented with two novel forms of data collection in the software development field: time diaries and direct observation. We found both methods to be feasible and to yield useful information about time utilization. In effect, we have quantified the effect of these social processes using the observational data. Among the insights gained from our time diary experiment are 1) developers switch between developments to minimize blocking and maximize overall throughput, and 2) there is a high degree of dynamic reassignment in response to changing project and organizational priorities. Among the insights gained from our direct observation experiment are 1) time diaries are a valid and accurate instrument with respect to their level of resolution, 2) unplanned interruptions constitute a significant time factor, and 3) the amount and kinds of communication are significant time and social factors.- 2-1

Functional and Biomechanical Effects of the Edge-to-Edge Repair in the Setting of Mitral Regurgitation: Consolidated Knowledge and Novel Tools to Gain Insight into Its Percutaneous Implementation

Mitral regurgitation is the most prevalent heart valve disease in the western population. When severe, it requires surgical treatment, repair being the preferred option. The edge-to-edge repair technique treats mitral regurgitation by suturing the leaflets together and creating a double-orifice valve. Due to its relative simplicity and versatility, it has become progressively more widespread. Recently, its percutaneous version has become feasible, and has raised interest thanks to the positive results of the Mitraclip(\uae) device. Edge-to-edge features and evolution have stimulated debate and multidisciplinary research by both clinicians and engineers. After providing an overview of representative studies in the field, here we propose a novel computational approach to the most recent percutaneous evolution of the edge-to-edge technique. Image-based structural finite element models of three mitral valves affected by posterior prolapse were derived from cine-cardiac magnetic resonance imaging. The models accounted for the patient-specific 3D geometry of the valve, including leaflet compound curvature pattern, patient-specific motion of annulus and papillary muscles, and hyperelastic and anisotropic mechanical properties of tissues. The biomechanics of the three valves throughout the entire cardiac cycle was simulated before and after Mitraclip(\uae) implantation, assessing the biomechanical impact of the procedure. For all three simulated MVs, Mitraclip(\uae) implantation significantly improved systolic leaflets coaptation, without inducing major alterations in systolic peak stresses. Diastolic orifice area was decreased, by up to 58.9%, and leaflets diastolic stresses became comparable, although lower, to systolic ones. Despite established knowledge on the edge-to-edge surgical repair, latest technological advances make its percutanoues implementation a challenging field of research. The modeling approach herein proposed may be expanded to analyze clinical scenarios that are currently critical for Mitraclip(\uae) implantation, helping the search for possible solutions

Deltoid, triceps, or both responses improve the success rate of the interscalene catheter surgical block compared with the biceps response

Background The influence of the muscular response elicited by neurostimulation on the success rate of interscalene block using a catheter (ISC) is unknown. In this investigation, we compared the success rate of ISC placement as indicated by biceps or deltoid, triceps, or both twitches. Methods Three hundred (ASA I-II) patients presenting for elective arthroscopic rotator cuff repair were prospectively randomized to assessment by biceps (Group B) or deltoid, triceps, or both twitches (Group DT). All ISCs were placed with the aid of neurostimulation. The tip of the stimulating needle was placed after disappearance of either biceps or deltoid, triceps, or both twitches at 0.3 mA. The catheter was advanced 2-3 cm past the tip of the needle and the block was performed using 40 ml ropivacaine 0.5%. Successful block was defined as sensory block of the supraclavicular nerve and sensory and motor block involving the axillary, radial, median, and musculocutaneous nerves within 30 min. Results Success rate was 98.6% in Group DT compared with 92.5% in Group B (95% confidence interval 0.01-0.11; P<0.02). Supplemental analgesics during handling of the posterior part of the shoulder capsule were needed in two patients in Group DT and seven patients in Group B. Three patients in Group B had an incomplete radial nerve distribution anaesthesia necessitating general anaesthesia. One patient in Group B had an incomplete posterior block extension of the supraclavicular nerve. No acute or late complications were observed. Conclusions Eliciting deltoid, triceps, or both twitches was associated with a higher success rate compared with eliciting biceps twitches during continuous interscalene bloc

Snail Trails and Cell Microcrack Impact on PV Module Maximum Power and Energy Production

—This paper analyzes the impact of the snail trail phenomena on photovoltaic (PV) module performances and energy production. Several tests (visual inspection, maximum power determination, dielectric withstand, wet leakage current, and electroluminescence test) were carried out on 31 PV modules located in a PV plant in Italy. The electroluminescence test highlighted the strong correlation between the appearance of snail trails and presence of damaged cells in PV modules. The daily energy produced by four PV modules affected by snail trails ranged between 68% and 88% of the energy produced by a damage free commercial PV module over the same period

Dynamic and quantitative evaluation of degenerative mitral valve disease: A dedicated framework based on cardiac magnetic resonance imaging

Background: Accurate quantification of mitral valve (MV) morphology and dynamic behavior over the cardiac cycle is crucial to understand the mechanisms of degenerative MV dysfunction and to guide the surgical intervention. Cardiac magnetic resonance (CMR) imaging has progressively been adopted to evaluate MV pathophysiology, although a dedicated framework is required to perform a quantitative assessment of the functional MV anatomy. Methods: We investigated MV dynamic behavior in subjects with normal MV anatomy (n=10) and patients referred to surgery due to degenerative MV prolapse, classified as fibro-elastic deficiency (FED, n=9) and Barlow's disease (BD, n=10). A CMR-dedicated framework was adopted to evaluate prolapse height and volume and quantitatively assess valvular morphology and papillary muscles (PAPs) function over the cardiac cycle. Multiple comparison was used to investigate the hallmarks associated to MV degenerative prolapse and evaluate the feasibility of anatomical and functional distinction between FED and BD phenotypes. Results: On average, annular dimensions were significantly (P < 0.05) larger in BD than in FED and normal subjects while no significant differences were noticed between FED and normal. MV eccentricity progressively decreased passing from normal to FED and BD, with the latter exhibiting a rounder annulus shape. Over the cardiac cycle, we noticed significant differences for BD during systole with an abnormal annular enlargement between mid and late systole (LS) (P < 0.001 vs. normal); the PAPs dynamics remained comparable in the three groups. Prolapse height and volume highlighted significant differences among normal, FED and BD valves. Conclusions: Our CMR-dedicated framework allows for the quantitative and dynamic evaluation of MV apparatus, with quantifiable annular alterations representing the primary hallmark of severe MV degeneration. This may aid surgeons in the evaluation of the severity of MV dysfunction and the selection of the appropriate MV treatment

3^3He Structure and Mechanisms of p3p^3He Backward Elastic Scattering

The mechanism of $p^3$He backward elastic scattering is studied. It is found that the triangle diagrams with the subprocesses $pd\to ^3$He$\pi^0$, $pd^*\to ^3$He$\pi^0$ and $p(pp)\to^3$He$\pi^+$, where $d^*$ and $pp$ denote the singlet deuteron and diproton pair in the $^1S_0$ state, respectively, dominate in the cross section at 0.3-0.8 GeV, and their contribution is comparable with that for a sequential transfer of a $np$ pair at 1-1.5 GeV. The contribution of the $d^*+pp$, estimated on the basis of the spectator mechanism of the $p(NN)\to ^3$He$\pi$ reaction, increases the $p^3$He$\to ^3$He$p$ cross section by one order of magnitude as compared to the contribution of the deuteron alone. Effects of the initial and final states interaction are taken into account.Comment: 17 pages, Latex, 4 postscript figures, expanded version, accepted by Physical Review

Mood Lifters: Increasing Accessibility to Mental Health Care through a Novel Peer-Led Approach

Nearly one in two people will experience a mental illness over the course of their lifetime and only 43% of individuals requiring care will access it (Kessler et al., 2005; National Institute of Mental Health [NIMH], 2017). New interventions, such as e-therapy, mobile applications and workplace wellness programs, have been developed to address barriers to care; however, they have inconsistent support and many introduce new barriers to care (Barak et al., 2008; Lui et al., 2017; Ivandic et al., 2017). A new program, Mood Lifters, an intervention with peer-led skills-based group meetings, was developed to further address barriers to care. Study 1 tested the feasibility of the program and future study structure in a series of pilot studies. Results suggested that the program and study structure were feasible. Study 2 explored the results of the semi-randomized, to treatment or waitlist conditions, control trial to determine the efficacy of the program. Multiple imputation was used to account for unexpected attrition. Results indicated that individuals in the program, when compared to the waitlist control condition, saw statistically significant improvements in anxiety, and that individuals who completed more homework saw statistically significant improvements in anxiety and perceived stress. Study 3 examined the efficacy of peer leaders compared to professional leaders. Results showed that there were no differences between leader types for attendance, homework completion or mood improvement. Overall, the findings from these studies suggest that the Mood Lifters program is feasible, that individuals engaged with the Mood Lifters program experience reductions in anxiety symptoms and perceived stress, and that the program is effectively delivered by peer leaders. Taken together, this dissertation suggests that Mood Lifters may offer hope to millions of individuals struggling with anxiety, depression and problems in living.PHDPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162945/1/cmvotta_1.pd

Study of suprathermal electron dynamics by modelling the electron cyclotron emission

LAUREA MAGISTRALEGli elettroni che orbitano intorno a linee del campo magnetico emettono radiazione alla frequenza di ciclotrone Ωc = neB/(γm), dove e rappresenta la carica elementare, B l’ampiezza del campo magnetico, m la massa a riposo dell’elettrone, γ il fattore relativis- tico e n il numero armonico. Questa radiazione è chiamata emissione ciclotronica degli elettroni (ECE). In presenza di un gradiente nell’ampiezza del campo magnetico, come nei tokamak, l’origine dell’emissione è legata alla frequenza dell’emissione e il profilo di temperatura elettronica può essere ricostruito scandendo un range di frequenze, che è lo scopo generale delle diagnostica ECE. Tuttavia, la definizione di temperatura assume che il plasma sia in equilibrio termico con una distribuzione di velocità maxwelliana per le sue particelle. In determinati scenari, il plasma può contenere una porzione significativa di particelle sovratermiche la cui energia supera quella delle particelle termiche di diversi ordini di grandezza. La presenza di una popolazione significativa di elettroni sovrater- mici influisce sia sulle misurazioni della temperatura che sulla ricostruzione del profilo degli elettroni. La diagnostica ECE può comunque fornire informazioni preziose sulla dis- tribuzione degli elettroni sovratermici nello spazio delle fasi. La misura della ECE a varie frequenze lungo una linea di vista verticale (VECE) con ampiezza del campo magnetico costante B fornisce una scansione dell’energia degli elettroni tramite il fattore relativis- tico γ. La ricostruzione della funzione di distribuzione degli elettroni a partire dalle misurazioni della ECE è un problema mal condizionato e un approccio più promettente consiste nella costruzione di una diagnostica sintetica equivalente che fornisce simulazioni che possono essere direttamente confrontate con le misurazioni dell’ECE. In questo lavoro viene costruita una nuova diagnostica sintetica per l’ECE che include l’effetto degli elet- troni sovratermici: il codice Yoda. Questo codice è in grado di calcolare: i) l’emissione ed il (ri)assorbimento di EC sulla base della funzione di distribuzione degli elettroni calcolata utilizzando il codice 3-D bounce-averaged guiding center relativistic Fokker-Planck Luke, per una linea di vista arbitraria simulata utilizzando il codice di ray-tracing c3po, che modella anche il sistema di rilevamento; ii) il trasporto dell’intensità della radiazione di EC lungo il percorso di propagazione. In questo lavoro, il codice Yoda viene sia validato per plasmi termici e che utilizzato per applicazioni dirette in due esperimenti di guida di corrente di elettrone ciclotrone (ECCD), ottenendo buoni risultati dai confronti diretti tra i trend delle misure sperimentali della ECE verticale e le intensità sintetiche, aprendo così nuove strade allo studio degli elettroni sovratermici nei tokamak.Electrons gyrating around magnetic field lines emit radiation at the frequency Ωc = n eB/(γm), where e is the elementary charge, B is the magnetic field amplitude, m is the electron rest mass, γ is the ralitivistic factor and n is the harmonic number. This radiation mechanism is called electron cyclotron emission (ECE). In the presence of a magnetic field amplitude gradient, as in a tokamak, the origin of emission is related to the frequency of the emission and a temperature profile can be reconstructed by scanning a range of frequencies, which is the general purpose of ECE diagnostics. The definition of temperature assumes that the plasma is in thermal equilibrium with a Maxwellian velocity distribution for its particles. In certain scenarios, the plasma may contain a significant proportion of suprathermal particles whose energy exceeds that of the thermal particles by several orders of magnitude, affecting both temperature measurements and profile reconstruction. Measuring ECE at various frequencies along vertical lines of sight (VECE) with constant magnetic field amplitude B provides a scan in electron energy via the relativistic factor γ. On the other hand, reconstructing the 3D bounce-averaged guiding center electron distribution function from ECE measurements is an ill-conditioned problem and a more promising approach consists of constructing an equivalent synthetic ECE diagnostic providing simulations that can be directly compared to measurements. A new general synthetic ECE diagnostic that includes the effect of suprathermal electrons is constructed: the Yoda code. This code is able to calculate: i) the EC emission and (re)absorption based on any arbitrary numerical electron distribution function calculated by any first-principle kinetic codes (as the 3-D bounce-averaged relativistic Fokker-Planck code Luke) for arbitrary line of sight simulated using the c3po ray-tracing code (which also model the detection system); ii) the transport of EC radiated intensity along the propagation path. In this work, the Yoda code is validated for thermal plasmas, and two direct application to TCV tokamak electron cyclotron current drive (ECCD) experiments are envisioned with good agreement between the experimental vertical ECE measurements and synthetic intensity trends, opening new paths regarding suprathermal electron studies in tokamak plasmas