You Won the Battle. What about the War? A Model of Competition between Proprietary and Open Source Software

Although open source software has recently attracted a relevant body of economic literature, a formal treatment of the process of com- petition with its proprietary counterpart is still missing. Starting from an epidemic model of innovation di?usion, we try to ?ll this gap. We propose a model where the two competing technologies depend on dif- ferent factors, each one speci?c to its own mode of production (prof- its and developers’ motivations respectively), together with network e?ects and switching costs. As the speed of di?usion of these tech- nologies is crucial for the ?nal outcome, we endogenize the parame- ter in?uencing it across the population of adopters. We ?nd that an asymptotically stable equilibrium where both technologies coexist can always be present and, when the propagation coe?cient is endogenous, it coexists with winner–take–all solutions. Furthermore, an increase in the level of the switching costs for one technology increases the num- ber of its adopters, while reducing the number of the other one. If the negative network e?ects increase for one of the two technologies, then the equilibrium level of users of that technology decrease.Increasing returns; Open-source software; Technological competition; Technology di?usion

Counteracting cocaine production: an analysis based on a novel dataset

he debate about the effectiveness of the counteracting policies against the supply of drugs, in particular of cocaine, is very lively and intense. Indeed, since many opinions are based on certain measures rather than others, the construction of reliable indicators is one of the preconditions for a correct and concerted assessment of drug supply. The lack of reliable data on drug provision derives, on the one side, from the objective difficulties encountered in assessing the quantitative elements of drug production and drug trafficking due to its illegal nature, and, on the other side, from the lack of a standard methodological approach to the issue. This paper tries to contribute to the topic by proposing a new dataset, based on a completely new approach to the problem of measuring drug supply. We put forward a unique dataset covering cocaine related seizures in Colombia for the whole of year 2008. Data have been collected on a daily basis from the websites of the main organizations fighting against drug traffickers (Army, Air Force, National Police, Departamento Administrativo de Seguridad, Armada Nacional, Fiscalia), detailing each single seizure of laboratories for the production of both basic paste and cocaine hydrochloride. By means of this dataset, we offer some accounts of the main numbers on drug supply and on drug seizures, suggesting some policy options, and arriving to an estimate of cocaine production

Efficient Strategies for Partitioning and Querying a Hirerchical Document Space

We consider a problem arising in the efficient management of a Hierachical Document Space, i,e.,partitioning the leaves of a tree among a set of servers in such a way that it is possible to take full advantage of the hierarchical system to efficiently answer user\u27s queries. After providing that the problem is NP-Hard, we devise efficient approximate solutions, and we make a number of experiments which show that allowing for very little space inefficiency can be instrumental to acheiving a significant improvement in the query efficiency

Intrauterine parvovirus B19 infection: early prenatal diagnosis is possible

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Intrusion Detection at Packet Level by Unsupervised Architectures

Intrusion Detection Systems (IDS’s) monitor the traffic in computer networks for detecting suspect activities. Connectionist techniques can support the development of IDS’s by modeling ‘normal’ traffic. This paper presents the application of some unsupervised neural methods to a packet dataset for the first time. This work considers three unsupervised neural methods, namely, Vector Quantization (VQ), Self-Organizing Maps (SOM) and Auto-Associative Back-Propagation (AABP) networks. The former paradigm proves quite powerful in supporting the basic space-spanning mechanism to sift normal traffic from anomalous traffic. The SOM attains quite acceptable results in dealing with some anomalies while it fails in dealing with some others. The AABP model effectively drives a nonlinear compression paradigm and eventually yields a compact visualization of the network traffic progression

Comparison of the clinical usefulness of different urinary tests for the initial detection of bladder cancer: a systematic review

Objectives: The standard initial approach in patients with hematuria or other symptoms suggestive of bladder cancer (BC) is a combination of cystoscopy and urine cytology (UC); however, UC has low sensitivity particularly in low-grade tumors. The aim of the present review was to critically analyze and compare results in the literature of promising molecular urinary tests for the initial diagnosis of BC. Methods: We searched in the Medline and Cochrane Library databases for literature from January 2009 to January 2019, following the PRISMAguidelines. Results: In terms of sensitivity, ImmunoCyt showed the highest mean and median value, higher than UC. All tests analyses showed higher mean and median sensitivity when compared with UC. In terms of specificity, only UroVysion and Microsatellite analyses showed mean and median values similar to those of UC, whereas for all other tests, the specificity was lower than UC. It is evident that the sensitivity of UC is particularly low in low grade BC. Urinary tests mainly had improved sensitivity when compared to UC, and ImmunoCyt and UroVysion had the highest improvement in low grade tumors. Conclusions: Most of the proposed molecular markers were able to improve the sensitivity with similar or lower specificity when compared to UC. However, variability of results among the different studies was strong. Thus, as of now, none of these markers presented evidences so as to be accepted by international guidelines for diagnosis of BC

Penggunaan Media Model dalam Pembelajaran IPA

This study aims to describe the increase in interest and student learning outcomes in science teaching in primary schools. Classroom action research was conducted in two cycles, each cycle consisted of two meetings with the various forms of energy and material use. Research subjects elementary school students grade IV No 20 Gunung Pangilun Padang Utara. The instrument of this study is the observation sheet student\u27s interests, learning activities observation sheets, and achievement test students\u27 interest in learning the instrument. The results showed that students\u27 interest in learning science in one cycle is 64.4 percent, and in the second cycle of 82.2 percent. Student learning outcomes in a single cycle on average 63.5 and 83.5 in the two cycle becomes. Besides that, it also revealed that an increasing mastery learning students from one cycle is 45.8 percent and in the second cycle of 91.6 percent. Analysis of teachers in implementing learning activities in a cycle that is 79.1 per cent and 91.6 per cent of the second cycle. The use of models in the media can increase interest in science learning, learning outcomes and teacher activities . Therefore, the model can be used medium primary school teachers as one of the media in learning science . Besides, teachers also need to make a good plan in accordance with the science curriculum in elementary schools

Disciplinary problems among high achiever students: the types and the causes

This qualitative study has been done to 24 teachers and 72 students from various secondary schools in Penang, Malaysia, in order to investigate the effect of between class ability grouping (BCAG) on high achiever secondary school students. Studies reported that BCAG triggered correspondence bias among teachers, which eventually affect them to show different perception and expectations towards high achiever classes (HAC) and low achiever classes (LAC) students. Symbolic interaction theories explained that individuals tend to be affected by others’ expectation, and therefore behave in a way they were expected to. Therefore, according to the previous studies on BCAG, it was assumed that HAC students would achieve better and would not be significantly involved in disciplinary problems. After semi-structured interview had been conducted in order to collect the data, and two-cycled analyses method, namely In-Vivo and Thematic Analyses had been operated in order to analyze the massive amount of qualitative data, the it was discovered that HAC students were involved with disciplinary problems, such as being disrespectful to teachers, paying less attention in the classroom, neglecting assignments and doing external work during classes. Other findings of this study showed that the disciplinary problems among HAC are related to their self-esteem types due to locus of control difference, as well as bigger issues apart from the competition among themselves. School management system, BCAG itself, reciprocal envy between HAC and LAC students, as well as their inclination towards tuition centers contributed to disciplinary problems among HAC students