923 resultados para centripetal and centrifugal forces
Resumo:
Infrared spectra of thoformaldehyde, H2CS and D2CS, were observed in the gas phase at a resolution of better than 0.1 cm−1 from 4000 to 400 cm−1 using a Nicolet FTIR system. Vibrational band origins and rotational constants were determined for ν2, ν3, ν4, and ν6 of H2CS and for ν1, ν2, ν3, ν4, and ν6 of D2CS. The ν3, ν4, and ν6 bands of H2CS were analyzed as a set of three Coriolis interacting bands, and three Coriolis constants were determined; similarly the ν4 and ν6 bands of D2CS were analyzed as a pair of interacting bands and one Coriolis constant was determined. A general harmonic force field was determined, without constraints, to fit the vibrational wavenumbers, Coriolis constants, and centrifugal distortion constants. A zero-point (rz) structure was determined from the ground-state rotational constants, and the equilibrium (re) bond lengths were estimated.
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A method is discussed for imposing any desired constraint on the force field obtained in a force constant refinement calculation. The application of this method to force constant refinement calculations for the methyl halide molecules is reported. All available data on the vibration frequencies, Coriolis interaction constants and centrifugal stretching constants of CH3X and CD3X molecules were used in the refinements, but despite this apparent abundance of data it was found that constraints were necessary in order to obtain a unique solution to the force field. The results of unconstrained calculations, and of three different constrained calculations, are reported in this paper. The constrained models reported are a Urey—Bradley force field, a modified valence force field, and a constraint based on orbital-following bond-hybridization arguments developed in the following paper. The results are discussed, and compared with previous results for these molecules. The third of the above models is found to reproduce the observed data better than either of the first two, and additional reasons are given for preferring this solution to the force field for the methyl halide molecules.
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Vibration-rotation spectra of HOCl have been measured at a resolution of 0.05 cm−1 to determine vibration rotation constants, and 35–37 Cl isotope shifts in the vibration frequencies. The spectrum of DOCl has also been recorded, and a preliminary analysis for the band origins has been made. The vibrational frequency data and centrifugal distortion constants have been used to determine the harmonic force field in a least-squares refinement; the force field obtained also gives a good fit to data on the vibrational contributions to the inertial defect. The equilibrium rotational constants of HOCl have been obtained, and an equilibrium structure has been estimated.
Resumo:
Vibration rotation spectra of HO15 NO and DO15 NO have been measured at a resolution of 0•04 cm-1 to determine the isotopic shifts in the vibrational band origins. These have been used together with recently determined data on the vibrational band origins, Coriolis constants, and centrifugal distorition constants, to determine the harmonic force field of both cis and trans nitrous acid in least squares refinement calculations. The results are discussed in relation to recent ab initio calculations, the inertia defects, and the torsional potential function.
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The problem of the appropriate distribution of forces among the fingers of a four-fingered robot hand is addressed. The finger-object interactions are modelled as point frictional contacts, hence the system is indeterminate and an optimal solution is required for controlling forces acting on an object. A fast and efficient method for computing the grasping and manipulation forces is presented, where computation has been based on using the true model of the nonlinear frictional cone of contact. Results are compared with previously employed methods of linearizing the cone constraints and minimizing the internal forces.
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Classical counterinsurgency theory – written before the 19th century – has generally strongly opposed atrocities, as have theoreticians writing on how to conduct insurgencies. For a variety of reasons – ranging from pragmatic to religious or humanitarian – theoreticians of both groups have particularly argued for the lenient treatment of civilians associated with the enemy camp, although there is a marked pattern of exceptions, for example, where heretics or populations of cities refusing to surrender to besieging armies are concerned. And yet atrocities – defined here as acts of violence against the unarmed (non-combatants, or wounded or imprisoned enemy soldiers), or needlessly painful and/or humiliating treatment of enemy combatants, beyond any action needed to incapacitate or disarm them – occur frequently in small wars. Examples abound where these exhortations have been ignored, both by forces engaged in an insurgency and by forces trying to put down a rebellion. Why have so many atrocities been committed in war if so many arguments have been put forward against them? This is the basic puzzle for which the individual contributions to this special issue are seeking to find tentative answers, drawing on case studies.
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This paper presents an overview of the European Union involvement in agricultural restructuring. By way of introduction it looks at the processes of farm replication operating in Europe and the forces behind them. It then considers the wider application of EU measures in each Member State and how they interrelate with the national property laws and social customs. In conclusion the paper appraises the restructuring policies by examining the balance between legitimising the concentration of property rights amongst a minority and the fragmentation of estates between the majority.
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Private sector commercial property represents some #400 bn, or 34% of total UK business assets and is a vital fabric for housing commercial enterprise. Yet social and economic forces for change, linked with new technology, are making owners and occupiers question the very nature and purpose of property and real estate.
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Large, well-documented wildfires have recently generated worldwide attention, and raised concerns about the impacts of humans and climate change on wildfire regimes. However, comparatively little is known about the patterns and driving forces of global fire activity before the twentieth century. Here we compile sedimentary charcoal records spanning six continents to document trends in both natural and anthropogenic biomass burning for the past two millennia. We find that global biomass burning declined from AD 1 to 1750, before rising sharply between 1750 and 1870. Global burning then declined abruptly after 1870. The early decline in biomass burning occurred in concert with a global cooling trend and despite a rise in the human population. We suggest the subsequent rise was linked to increasing human influences, such as population growth and land-use changes. Our compilation suggests that the final decline occurred despite increasing air temperatures and population. We attribute this reduction in the amount of biomass burned over the past 150 years to the global expansion of intensive grazing, agriculture and fire management.
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This book is highly topical considering the recent resurgence of violence by the PKK, the incursions into Northern Iraq by the Turkish army and security forces and Turkey’s EU accession negotiations. Turkey has become an increasingly important player in Middle Eastern geopolitics. More than two decades of serious conflict in Turkey are proving to be a barrier to improved relations between Turkey and the EU. This book is the first study to address fully the legal and political dimensions of the conflict, and their impact on mechanisms for conflict resolution in the region, offering a scholarly exploration of a debate that is often politically and emotionally highly charged. Kerim Yildiz and Susan Breau look at the practical application of the law of armed conflicts to the ongoing situation in Turkey and Northern Iraq. The application of the law in this region also means addressing larger questions in international law, global politics and conflict resolution. Examples include belligerency in international law, whether the ‘war on terror’ has resulted in changes to the law of armed conflict and terrorism and conflict resolution. The Kurdish Conflict explores the practical possibilities of conflict resolution in the region, examining the political dynamics of the region, and suggesting where lessons can be drawn from other peace processes, such as in Northern Ireland. This book will be of great value to policy-makers, regional experts, and others interested in international humanitarian law and conflict resolution.
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‘White Youth’ recovers and explains the relationship between far-right organisations and British youth culture in the period between 1977 and 1987. In particular, it concentrates on the cultural spaces opened up by punk and the attempts made by the National Front and British Movement to claim them as conduits for racist and/or ultra-nationalist politics. The article is built on an empirical basis, using archival material and a historical methodology chosen to develop a history ‘from below’ that takes due consideration of the socio-economic and political forces that inform its wider context. Its focus is designed to map shifting cultural and political influences across the far right, assessing the extent to which extremist organisations proved able to adopt or utilise youth cultural practice as a means of recruitment and communication. Today the British far right is in political and organisational disarray. Nonetheless, residues tied to the cultural initiatives devised in the 1970s–80s remain, be they stylistic, nostalgic or points of connection forged to connect a transnational music scene.
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This investigation shall focus upon the issue of legalized abortion. I believe the complex controversy surrounding the issue of abortion, demonstrates more clearly than any other single contemporary issue the social, political, moral and religious forces working for change in a post-Reagan America. I shall examine in depth the theology, writings, strategies and activities of those Americans who seek to express themselves and their beliefs in religious, or religiously supported interest groups. The current debate surrounding abortion legislation lends itself to several forms of analysis: religious, political, sociological, etc. I will write from the perspective of a student of religion. I shall focus more upon the religious, moral and theological conviction-s of the abortion activists than upon their constitutional right to free speech or assembly. I shall give more attention to denominational structures and church/state relations than to the structuring of representative districts and democratic theory.
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This work presents a fully operational interstate CGE model implemented for the Brazilian economy that tries to quantify both the role of barriers to trade on economic growth and foreign trade performance and how the distribution of the economic activity may change as the country opens up to foreign trade. Among the distinctive features embedded in the model, modeling of external scale economies, port efficiency and land-maritime transport costs provides an innovative way of dealing explicitly with theoretical issues related to integrated regional systems. In order to illustrate the role played by the quality of infrastructure and geography on the country‟s foreign and interregional trade performance, a set of simulations is presented where barriers to trade are significantly reduced. The relative importance of trade policy, port efficiency and land-maritime transport costs for the country trade relations and regional growth is then detailed and quantified, considering both short run as well as long run scenarios. A final set of simulations shed some light on the effects of liberal trade policies on regional inequality, where the manufacturing sector in the state of São Paulo, taken as the core of industrial activity in the country, is subjected to different levels of external economies of scale. Short-run core-periphery effects are then traced out suggesting the prevalence of agglomeration forces over diversion forces could rather exacerbate regional inequality as import barriers are removed up to a certain level. Further removals can reverse this balance in favor of diversion forces, implying de-concentration of economic activity. In the long run, factor mobility allows a better characterization of the balance between agglomeration and diversion forces among regions. Regional dispersion effects are then clearly traced-out, suggesting horizontal liberal trade policies to benefit both the poorest regions in the country as well as the state of São Paulo. This long run dispersion pattern, on one hand seems to unravel the fragility of simple theoretical results from recent New Economic Geography models, once they get confronted with more complex spatially heterogeneous (real) systems. On the other hand, it seems to capture the literature‟s main insight: the possible role of horizontal liberal trade policies as diversion forces leading to a more homogeneous pattern of interregional economic growth.
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Issues related to the reality of lesbian, gay, bisexual and transgender (LGBT) individuals are being incorporated into institutional and social discourses, and show the challenges that must be overcome towards citizenship. The inclusion of gay rights in the domain of institutions like the United Nations and the Brazilian Secretariat of Human Rights are a response to broader movements that places the gay subject as an important topic of debate in the social-political sphere. In this scenario, some institutions deserve close attention from researchers related to gay issues, the business environment being a good example. In this domain, diversity has become an important topic of debate between scholars, where the question of sexual identity in most cases does not appear. The literature that actually focuses on the theme is explored through approaches that are not able to break with universalisms and a normatized vocabulary. Therefore, this research explores discursive structures related to sexuality and examines the meanings construed throughout these structures as described by gay individuals working in business. Furthermore, it investigates patterns of discursive normative structures and consequential challenges faced by gay people in the working environment, and also complements the current debate both in the socio-political sphere and in academic reality on LGBT challenges. The Foucauldian notions of discourse, knowledge and power, and the main concepts of queer theory are incorporated to the analysis, as well as concepts related to the politics of post-colonial sexuality, subordination, and hegemonic forces, together with role of reflexivity in modernity and its impacts on secularized mental structures. The research design takes a phenomenological approach and bases its knowledge claim on a participatory perspective, where the sample chosen for data collection consisted of gay individuals working in the business environment, aiming at generate categories of meanings through the description of their experiences.
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Since the international financial and food crisis that started in 2008, strong emphasis has been made on the importance of Genetically Modified Organisms (GMOs) (or “transgenics”) under the claim that they could contribute to increase food productivity at a global level, as the world population is predicted to reach 9.1 billion in the year 2050 and food demand is predicted to increase by as much as 50% by 2030. GMOs are now at the forefront of the debates and struggles of different actors. Within civil society actors, it is possible to observe multiple, and sometime, conflicting roles. The role of international social movements and international NGOs in the GMO field of struggle is increasingly relevant. However, while many of these international civil society actors oppose this type of technological developments (alleging, for instance, environmental, health and even social harms), others have been reportedly cooperating with multinational corporations, retailers, and the biotechnology industry to promote GMOs. In this thesis research, I focus on analysing the role of “international civil society” in the GMO field of struggle by asking: “what are the organizing strategies of international civil society actors, such as NGOs and social movements, in GMO governance as a field of struggle?” To do so, I adopt a neo-Gramscian discourse approach based on the studies of Laclau and Mouffe. This theoretical approach affirms that in a particular hegemonic regime there are contingent alliances and forces that overpass the spheres of the state and the economy, while civil society actors can be seen as a “glue” to the way hegemony functions. Civil society is then the site where hegemony is consented, reproduced, sustained, channelled, but also where counter-hegemonic and emancipatory forces can emerge. Considering the importance of civil society actors in the construction of hegemony, I also discuss some important theories around them. The research combines, on the one hand, 36 in-depth interviews with a range of key civil society actors and scientists representing the GMO field of struggle in Brazil (19) and the UK (17), and, on the other hand, direct observations of two events: Rio+20 in Rio de Janeiro in 2012, and the first March Against Monsanto in London in 2013. A brief overview of the GMO field of struggle, from its beginning and especially focusing in the 1990s when the process of hegemonic formation became clearer, serves as the basis to map who are the main actors in this field, how resource mobilization works, how political opportunities (“historical contingencies”) are discovered and exploited, which are the main discourses (“science” and “sustainability” - articulated by “biodiversity preservation”, “food security” and “ecological agriculture”) articulated among the actors to construct a collective identity in order to attract new potential allies around “GMOs” (“nodal point”), and which are the institutions and international regulations within these processes that enable hegemony to emerge in meaningful and durable hegemonic links. This mapping indicates that that the main strategies applied by the international civil society actors are influenced by two central historical contingencies in the GMO field of struggle: 1) First Multi-stakeholder Historical Contingency; and 2) “Supposed” Hegemony Stability. These two types of historical contingency in the GMO field of struggle encompass deeper hegemonic articulations and, because of that, they induce international civil society actors to rethink the way they articulate and position themselves within the field. Therefore, depending on one of those moments, they will apply one specific strategy of discourse articulation, such as: introducing a new discourse in hegemony articulation to capture the attention of the public and of institutions; endorsing new plural demands; increasing collective visibility; facilitating material articulations; sharing a common enemy identity; or spreading new ideological elements among the actors in the field of struggle.