Teaching the scientific method in the curriculum

 In chemistry education, students not only learn chemical knowledge and skills, but about the culture of chemistry – how scientists think about, and practise, chemistry. Students often learn that science is practised according to the “scientific method”, which is a model of scientific discovery, expounded by science historians and philosophers. The idealised “scientific method” has a number of steps: the collection of information about a phenomenon; the development of a hypothesis to explain those observations; an experiment to test a prediction that arises from the hypothesis, perhaps including more observations and collection of more information; improvement of the hypothesis; and so on.

The problem is that students (and even some science professionals) often do not understand the philosophy behind the scientific method and paradoxically, the scientific method does not seem to apply to most careers in science. The true nature of science is that concepts have been developed though variants of the “scientific method”, and that a process of testing the predictive value of these concepts has lead to advances in that conceptual knowledge. Hence the “scientific method” applies to the development of scientific ideas, not necessarily to the work of all scientists. It is not whether we personally use the scientific method in our day-today work, but how we use, apply, think about and communicate scientific knowledge and skills that makes us chemists.

What about us? We have careers too! The career experiences of Australian sport scientists

 he professionalisation of sport has provided career opportunities for athletes, coaches and sport scientists alike. The career development literature for athletes is well established and the empirical career literature for coaches is growing, but little is known about the careers of sport scientists. The purpose of this investigation was to explore and examine the career experiences of Australian sport scientists. In-depth interviews were conducted with six practicing Australian sport scientists at different career stages. Several themes emerged from the data on careers of sport scientists that are unique to sport. Sport scientists identify strongly with their role in sport success and yet they receive little recognition for what they do. All participants experienced career dissonance as they transitioned from practitioner to another career such as academia or sport management. Feelings of loss were identified by participants as their applied work diminished when they moved away from their early career service roles. All six participants believed that in order to advance their career in sport their options were moving overseas, working in academia, or retraining for a career in sports management. It is recommended that sport scientists be provided with better career education and more structured professional development.

Distribuições estatísticas: citações de publicações científicas e de cientistas

Pós-graduação em Física - IGCE

La Pace Calda. La nascita del movimento antinucleare negli Stati Uniti e in Gran Bretagna, 1957-1963

The aim of this proposal is to offer an alternative perspective on the study of Cold War, since insufficient attention is usually paid to those organizations that mobilized against the development and proliferation of nuclear weapons. The antinuclear movement began to mobilize between the 1950s and the 1960s, when it finally gained the attention of public opinion, and helped to build a sort of global conscience about nuclear bombs. This was due to the activism of a significant part of the international scientific community, which offered powerful intellectual and political legitimization to the struggle, and to the combined actions of the scientific and organized protests. This antinuclear conscience is something we usually tend to consider as a fait accompli in contemporary world, but the question is to show its roots, and the way it influenced statesmen and political choices during the period of nuclear confrontation of the early Cold War. To understand what this conscience could be and how it should be defined, we have to look at the very meaning of the nuclear weapons that has deeply modified the sense of war. Nuclear weapons seemed to be able to destroy human beings everywhere with no realistic forms of control of the damages they could set off, and they represented the last resource in the wide range of means of mass destruction. Even if we tend to consider this idea fully rational and incontrovertible, it was not immediately born with the birth of nuclear weapons themselves. Or, better, not everyone in the world did immediately share it. Due to the particular climate of Cold War confrontation, deeply influenced by the persistence of realistic paradigms in international relations, British and U.S. governments looked at nuclear weapons simply as «a bullet». From the Trinity Test to the signature of the Limited Test Ban Treaty in 1963, many things happened that helped to shift this view upon nuclear weapons. First of all, more than ten years of scientific protests provided a more concerned knowledge about consequences of nuclear tests and about the use of nuclear weapons. Many scientists devoted their social activities to inform public opinion and policy-makers about the real significance of the power of the atom and the related danger for human beings. Secondly, some public figures, as physicists, philosophers, biologists, chemists, and so on, appealed directly to the human community to «leave the folly and face reality», publicly sponsoring the antinuclear conscience. Then, several organizations leaded by political, religious or radical individuals gave to this protests a formal structure. The Campaign for Nuclear Disarmament in Great Britain, as well as the National Committee for a Sane Nuclear Policy in the U.S., represented the voice of the masses against the attempts of governments to present nuclear arsenals as a fundamental part of the international equilibrium. Therefore, the antinuclear conscience could be defined as an opposite feeling to the development and the use of nuclear weapons, able to create a political issue oriented to the influence of military and foreign policies. Only taking into consideration the strength of this pressure, it seems possible to understand not only the beginning of nuclear negotiations, but also the reasons that permitted Cold War to remain cold.

Synthesis and surface modification of semiconductor nanocrystals

The last decade has witnessed an exponential growth of activities in the field of nanoscience and nanotechnology worldwide, driven both by the excitement of understanding new science and by the potential hope for applications and economic impacts. The largest activity in this field up to date has been in the synthesis and characterization of new materials consisting of particles with dimensions in the order of a few nanometers, so-called nanocrystalline materials. [1-8] Semiconductor nanomaterials such as III/V or II/VI compound semiconductors exhibit strong quantum confinement behavior in the size range from 1 to 10 nm. Therefore, preparation of high quality semiconductor nanocrystals has been a challenge for synthetic chemists, leading to the recent rapid progress in delivering a wide variety of semiconducting nanomaterials. Semiconductor nanocrystals, also called quantum dots, possess physical properties distinctly different from those of the bulk material. Typically, in the size range from 1 to 10 nm, when the particle size is changed, the band gap between the valence and the conduction band will change, too. In a simple approximation a particle in a box model has been used to describe the phenomenon[9]: at nanoscale dimensions the degenerate energy states of a semiconductor separate into discrete states and the system behaves like one big molecule. The size-dependent transformation of the energy levels of the particles is called “quantum size-effect”. Quantum confinement of both the electron and hole in all three dimensions leads to an increase in the effective bandgap of the material with decreasing crystallite size. Consequently, both the optical absorption and emission of semiconductor nanaocrystals shift to the blue (higher energies) as the size of the particles gets smaller. This color tuning is well documented for CdSe nanocrystals whose absorption and emission covers almost the whole visible spectral range. As particle sizes become smaller the ratio of surface atoms to those in the interior increases, which has a strong impact on particle properties, too. Prominent examples are the low melting point [8] and size/shape dependent pressure resistance [10] of semiconductor nanocrystals. Given the size dependence of particle properties, chemists and material scientists now have the unique opportunity to change the electronic and chemical properties of a material by simply controlling the particle size. In particular, CdSe nanocrystals have been widely investigated. Mainly due to their size-dependent optoelectronic properties [11, 12] and flexible chemical processibility [13], they have played a distinguished role for a number of seminal studies [11, 12, 14, 15]. Potential technical applications have been discussed, too. [8, 16-27] Improvement of the optoelectronic properties of semiconductor nanocrystals is still a prominent research topic. One of the most important approaches is fabricating composite type-I core-shell structures which exhibit improved properties, making them attractive from both a fundamental and a practical point of view. Overcoating of nanocrystallites with higher band gap inorganic materials has been shown to increase the photoluminescence quantum yields by eliminating surface nonradiative recombination sites. [28] Particles passivated with inorganic shells are more robust than nanocrystals covered by organic ligands only and have greater tolerance to processing conditions necessary for incorporation into solid state structures or for other applications. Some examples of core-shell nanocrystals reported earlier include CdS on CdSe [29], CdSe on CdS, [30], ZnS on CdS, [31] ZnS on CdSe[28, 32], ZnSe on CdSe [33] and CdS/HgS/CdS [34]. The characterization and preparation of a new core-shell structure, CdSe nanocrystals overcoated by different shells (CdS, ZnS), is presented in chapter 4. Type-I core-shell structures as mentioned above greatly improve the photoluminescence quantum yield and chemical and photochemical stability of nanocrystals. The emission wavelengths of type-I core/shell nanocrystals typically only shows a small red-shift when compared to the plain core nanocrystals. [30, 31, 35] In contrast to type-I core-shell nanocrystals, only few studies have been conducted on colloidal type-II core/shell structures [36-38] which are characterized by a staggered alignment of conduction and valence bands giving rise to a broad tunability of absorption and emission wavelengths, as was shown for CdTe/CdSe core-shell nanocrystals. [36] The emission of type-II core/shell nanocrystals mainly originates from the radiative recombination of electron-hole pairs across the core-shell interface leading to a long photoluminescence lifetime. Type-II core/shell nanocrystals are promising with respect to photoconduction or photovoltaic applications as has been discussed in the literature.[39] Novel type-II core-shell structures with ZnTe cores are reported in chapter 5. The recent progress in the shape control of semiconductor nanocrystals opens new fields of applications. For instance, rod shaped CdSe nanocrystals can enhance the photo-electro conversion efficiency of photovoltaic cells, [40, 41] and also allow for polarized emission in light emitting diodes. [42, 43] Shape control of anisotropic nanocrystals can be achieved by the use of surfactants, [44, 45] regular or inverse micelles as regulating agents, [46, 47] electrochemical processes, [48] template-assisted [49, 50] and solution-liquid-solution (SLS) growth mechnism. [51-53] Recently, formation of various CdSe nanocrystal shapes has been reported by the groups of Alivisatos [54] and Peng, [55] respectively. Furthermore, it has been reported by the group of Prasad [56] that noble metal nanoparticles can induce anisotropic growth of CdSe nanocrystals at lower temperatures than typically used in other methods for preparing anisotropic CdSe structures. Although several approaches for anisotropic crystal growth have been reported by now, developing new synthetic methods for the shape control of colloidal semiconductor nanocrystals remains an important goal. Accordingly, we have attempted to utilize a crystal phase control approach for the controllable synthesis of colloidal ZnE/CdSe (E = S, Se, Te) heterostructures in a variety of morphologies. The complex heterostructures obtained are presented in chapter 6. The unique optical properties of nanocrystals make them appealing as in vivo and in vitro fluorophores in a variety of biological and chemical investigations, in which traditional fluorescence labels based on organic molecules fall short of providing long-term stability and simultaneous detection of multiple emission colours [References]. The ability to prepare water soluble nanocrystals with high stability and quantum yield has led to promising applications in cellular labeling, [57, 58] deep-tissue imaging, [59, 60] and assay labeling [61, 62]. Furthermore, appropriately solubilized nanocrystals have been used as donors in fluorescence resonance energy transfer (FRET) couples. [63-65] Despite recent progress, much work still needs to be done to achieve reproducible and robust surface functionalization and develop flexible (bio-) conjugation techniques. Based on multi-shell CdSe nanocrystals, several new solubilization and ligand exchange protocols have been developed which are presented in chapter 7. The organization of this thesis is as follows: A short overview describing synthesis and properties of CdSe nanocrystals is given in chapter 2. Chapter 3 is the experimental part providing some background information about the optical and analytical methods used in this thesis. The following chapters report the results of this work: synthesis and characterization of type-I multi-shell and type-II core/shell nanocrystals are described in chapter 4 and chapter 5, respectively. In chapter 6, a high–yield synthesis of various CdSe architectures by crystal phase control is reported. Experiments about surface modification of nanocrystals are described in chapter 7. At last, a short summary of the results is given in chapter 8.

RESILIENT WOMEN, METISTIC SCIENTISTS: A MULTIPLE CASE STUDY OF HOW WOMEN NEGOTIATE THEIR SITUATEDNESS IN SCIENCE FIELDS

The concept of feminist metistic resilience postulates that the voiceless, the marginalized and the minority in societies employ strategies in order to turn tables in their favor. This study presents a qualitative analysis of how women, considered to be the minority, negotiate their situatedness in science fields in order to effect change in their lives or that of the society and why they become successful. By “situatedness,” I refer to the everyday life of women as they live and encounter people, society and culture, especially, the life of women who have transcended the culturally stipulated role of women and are excelling in a male dominated field. The study, in different dimensions, conceptualizes the reason for the fewer number of women in science; looks at how scientific methods and practices inhibit the development of women in science; and, finally, interrogates the question of objectivity in science. It becomes apparent, through feminist metistic resilience, that women become successful when they accept conventional practices in scientific arrangements and structures. They accept the practices by embracing and not questioning structures and arrangements that have shaped the field of science and by shifting shapes and assuming different forms in order to adapt to conditions they encounter. Apart from adapting and shape shifting, the women also become successful through environmental and social influences. My analysis suggests that more women can be encouraged to pursue science when women practicing science begin to question structures and arrangements that have shaped the practice of science over the centuries. The overall findings of the research provide implications for policy makers, educators and feminist researchers.

Climate Variability and Extremes during the Past 100 Years

Large progress has been made in the past few years towards quantifying and understanding climate variability during past centuries. At the same time, present-day climate has been studied using state-of-the-art data sets and tools with respect to the physical and chemical mechanisms governing climate variability. Both the understanding of the past and the knowledge of the processes are important for assessing and attributing the anthropogenic effect on present and future climate. The most important time period in this context is the past approximately 100 years, which comprises large natural variations and extremes (such as long droughts) as well as anthropogenic influences, most pronounced in the past few decades. Recent and ongoing research efforts steadily improve the observational record of the 20th century, while atmospheric circulation models are used to underpin the mechanisms behind large climatic variations. Atmospheric chemistry and composition are important for understanding climate variability and change, and considerable progress has been made in the past few years in this field. The evolving integration of these research areas in a more comprehensive analysis of recent climate variability was reflected in the organisation of a workshop “Climate variability and extremes in the past 100 years” in Gwatt near Thun (Switzerland), 24–26 July 2006. The aim of this workshop was to bring together scientists working on data issues together with statistical climatologists, modellers, and atmospheric chemists to discuss gaps in our understanding of climate variability during the past approximately 100 years.

Scientists’ situated knowledge: Strong objectivity in transdisciplinarity

Although transdisciplinary research has started addressing important epistemological challenges, as evidenced by the discussion about ‘mode 2’ knowledge production, its relation with postulations of ‘scientific objectivity’ is not yet well clarified. A common way of dealing with the epistemological challenge of situated knowledge production, as proposed by transdisciplinarity, is to point to the fundamental aspect of reflexivity. But reflexivity also includes being aware that power and control over the object is derived from the social position of researchers, an issue not often explicitly discussed in transdisciplinary research. Reflexivity thus represents an important but insufficient principle for guaranteeing appropriate levels of self-reflection within a process of knowledge coproduction. We therefore hypothesize that transdisciplinary research could greatly benefit from feminist scientific tradition, in particular the insights of standpoint theory and the concept of ‘strong objectivity’. We analyse, and reflect upon, how a recent transdisciplinary research initiative – conducted together with civil society organizations in (CSOs) in six countries: Bangladesh, Bolivia, Brazil, Burkina Faso, Ecuador and India – has benefited from the use of ‘strong objectivity’. We analyse how the social position of all stakeholders, including ourselves as the scientific actors in this initiative, influence the process and conditions of transdisciplinary knowledge co-production, and we discuss how power and control by scientists affects the process and conditions of interaction. Thereby we argue for the necessity of explicitly assuming sides in contested contexts for reaching objectivity in transdisciplinary research.