Size dependent exciton g-factor in self-assembled InAs/InP quantum dots

We have studied the size dependence of the exciton g-factor in self-assembled InAs/InP quantum dots. Photoluminescence measurements on a large ensemble of these dots indicate a multimodal height distribution. Cross-sectional Scanning Tunneling Microscopy measurements have been performed and support the interpretation of the macro photoluminescence spectra. More than 160 individual quantum dots have systematically been investigated by analyzing single dot magneto-luminescence between 1200nm and 1600 nm. We demonstrate a strong dependence of the exciton g-factor on the height and diameter of the quantum dots, which eventually gives rise to a sign change of the g-factor. The observed correlation between exciton g-factor and the size of the dots is in good agreement with calculations. Moreover, we find a size dependent anisotropy splitting of the exciton emission in zero magnetic field.Comment: 15 pages, 7 figure

Dreams of declassification - The early Cold War quest for nuclear knowledge in the Netherlands and Norway

This article seeks to explore the relation between nuclear physics and secrecy in early Cold War Europe. After World War II, nuclear physics re-emerged from the Manhattan Project as a largely classified field. Over time, the boundary between secret and unclassified information set by the United States moved due to both political and scientific developments. This shifting boundary of secrecy is taken as a place to investigate power relations in the context of Cold War Science. The Netherlands and Norway are two countries with early nuclear programs that tried to move this boundary, in part by building a joint reactor in 1951. Whereas they requested classified information from the US in 1946, their programs developed to a point where the US made requests to classify nuclear information in Europe by 1960. Between 1954 and 1960, the joint reactor program became the site of a multilateral intelligence operation. Secrecy was used as an intelligence tool to spread nuclear disinformation to the Soviet Union. This history shows how (de)classification opened and closed windows of opportunity and sheds light on the effectiveness of classification

The secrecy and science of Cold War atoms in the Netherlands and Norway

This study focuses on a unique nuclear collaboration between the Netherlands and Norway in the early Cold War, with special attention to the role of secrecy. A small joint research reactor was completed in Norway in July 1951. In addition, a small device to enrich uranium—a "calutron"—was realized in the summer of 1953 in Amsterdam. In those years America pursued a strict policy of secrecy and control of nuclear materials such as uranium. It was not until December 1953 that US President Eisenhower announced a relaxation of this policy; the "Atoms for Peace" program. The realization of these capabilities under a regime of maximum restrictions provides an ideal case for studying knowledge limitation and the relationship between science and secrecy. How did scientists and state officials deal with secrecy? How and why did the boundaries of secrecy shift over time? Three decisive factors can be identified for secret knowledge and technology to move: possession of special nuclear materials such as heavy water or uranium, scientists with a strong international network, and political will to support nuclear development. Norwegian and some Dutch assistance extended to third countries in the period up to 1960. Finally, secrecy was important in the joint project in a specific way: it enabled the production of scientific disinformation as a Cold War weapon. Openness and secrecy alternated to reflect changing power relations within Cold War science. As this history shows, secrecy is a convenient historiographical instrument to reveal such essential historical patterns

The secrecy and science of Cold War atoms in the Netherlands and Norway

This study focuses on a unique nuclear collaboration between the Netherlands and Norway in the early Cold War, with special attention to the role of secrecy. A small joint research reactor was completed in Norway in July 1951. In addition, a small device to enrich uranium—a "calutron"—was realized in the summer of 1953 in Amsterdam. In those years America pursued a strict policy of secrecy and control of nuclear materials such as uranium. It was not until December 1953 that US President Eisenhower announced a relaxation of this policy; the "Atoms for Peace" program. The realization of these capabilities under a regime of maximum restrictions provides an ideal case for studying knowledge limitation and the relationship between science and secrecy. How did scientists and state officials deal with secrecy? How and why did the boundaries of secrecy shift over time? Three decisive factors can be identified for secret knowledge and technology to move: possession of special nuclear materials such as heavy water or uranium, scientists with a strong international network, and political will to support nuclear development. Norwegian and some Dutch assistance extended to third countries in the period up to 1960. Finally, secrecy was important in the joint project in a specific way: it enabled the production of scientific disinformation as a Cold War weapon. Openness and secrecy alternated to reflect changing power relations within Cold War science. As this history shows, secrecy is a convenient historiographical instrument to reveal such essential historical patterns

An empirical framework of control methods of victims of human trafficking for sexual exploitation

Although human trafficking for sexual exploitation is a frequently discussed area in current research, especially on the way that human traffickers control their victims, a recurrent problem is the lack of empirical basis. The present study examines control methods (or conditions) used against 137 victims of human trafficking for sexual exploitation. A multidimensional scaling analysis (smallest space analysis (SSA-I)) of 23 control methods (and conditions) derived from a content analysis of police files from the Netherlands revealed three distinct forms of control. These could be interpreted in terms of Canter’s Victim Role model that has been the basis for differentiating offending styles in other violent interpersonal offences. Further analysis showed a relationship between these control styles and different types of prostitution. The three Victim as Object, Victim as Vehicle and Victim as Person modes are consistent with different control methods identified in previous research

Activities, Access Control, and Crime:a Quasi-Experimental Study regarding Entry Gates at Train Stations in the Netherlands

This article discusses a unique “natural experiment,” the introduction of entry gates at Dutch train stations and the potential effects of this on crime in the areas around these stations. A quasi-experimental study was carried out to show that introducing entry gates correlated with a drop in crime in these areas. After entry gates had been introduced, potential offenders could only enter train stations with a valid ticket, which meant that they would be less likely to enter or leave these stations and more likely to choose other places to hang around in or for entering and leaving trains. A dataset was created in which the crime rates around train stations were registered for each month in the years 2013 through 2018. The changing numbers of travelers at each station were also taken into account, as this variable probably correlates with the amount of crime. A two-way fixed-effects model was run on data for about 260 train stations, with and without entry gates, using the relative crime rate per thousand travelers as the dependent variable. Based on this relative crime rate, the use of entry gates was found to coincide with a decrease of 9% in crime, compared to a situation without entry gates. This study can inform policymakers about the potential effects of entry gates in particular and about situational crime prevention in general. Moreover, it illustrates how implementing measures at various locations at different moments enables the effectiveness of such measures to be tested more precisely and with more confidence

National Security vs Criminal law. Perspectives, Doubts and Concerns on the Criminalisation of Organised Crime in England and Wales

This paper will interpret and critically analyse the new offence for organised crime in England and Wales (Section 45 of the Serious Crime Act 2015) from a criminological perspective in light of evidence found in research in the country. It will argue that changes in the law relate to changes in political narratives rather than to variations in the criminal panorama of organised crime. It will discuss these changes within three perspectives, which address various levels of concern: a narrative perspective, which reflects on the overlapping of meanings in the use of the words ‘organised crime’; an evolution perspective, which reflects on the origins of the new participation offences with reference to both national and international pressures; a management perspective, which reflects on some of the immediate effects of the new offences of organised crime on the criminal justice system. This paper will conclude that political narratives have indeed influenced criminal policy, while there is no significant change in the phenomenon of organised crime to justify such narratives