3,031 research outputs found
The Electromotive Force and Free Energy of Dilution of Lithium Chloride in Aqueous and Alcoholic Solutions
Various experimental methods may be employed for comparing the activities of solutions of electrolytes, viz., freezing point, boiling point, vapor pressure, osmotic pressure, electrical conductivity and electromotive force. Of these, the latter is generally more convenient of application; it has the advantage in that measurements are more easily made and its use is not restricted to any particular temperature interval. In solutions ranging from the moderately dilute to the very concentrated it may be applied more accurately than the conductivity method. The electromotive force method, however, has its limitations. It shares with all of the other methods the disadvantage of being inapplicable for solutions other than those of the uni-univalent electrolytes. This, coupled with the troublesome factor of the boundary potential, has limited its usefulness
The initiation and development of metamorphic foliation in the Otago Schist, Part 2: evidence from quartz grain-shape data
Shape, size and orientation measurements of quartz grains sampled along two transects that cross zones of increasing metamorphic grade in the Otago Schist, New Zealand, reveal the role of quartz in the progressive development of metamorphic foliation. Sedimentary compaction and diagenesis contributed little to the formation of a shape-preferred orientation (SPO) within the analysed samples. Metamorphic foliation was initiated at sub-greenschist facies conditions as part of a composite S1-bedding structure parallel to the axial planes of tight to isoclinal F1 folds. An important component of this foliation is a pronounced quartz SPO that formed dominantly by the effect of dissolution?precipitation creep on detrital grains in association with F1 strain. With increasing grade, the following trends are evident from the SPO data: (i) a progressive increase in the aspect ratio of grains in sections parallel to lineation, and the development of blade-shaped grains; (ii) the early development of a strong shape preferred orientation so that blade lengths define the linear aspect of the foliation (lineation) and the intermediate axes of the blades define a partial girdle about the lineation; (iii) a slight thinning and reduction in volume of grains in the one transect; and (iv) an actual increase in thickness and volume in the survivor grains of the second transect. The highest-grade samples, within the chlorite zone of the greenschist facies, record segregation into quartz- and mica-rich layers. This segregation resulted largely from F2 crenulation and marks a key change in the distribution, deformation and SPO of the quartz grains. The contribution of quartz SPO to defining the foliation lessens as the previously discrete and aligned detrital quartz grains are replaced by aggregates and layers of dynamically recrystallized quartz grains of reduced aspect ratio and reduced alignment. Pressure solution now affects the margins of quartz-rich layers rather than individual grains. In higher-grade samples, therefore, the rock structure is characterized increasingly by segregation layering parallel to a foliation defined predominantly by mica SPO
Energy Analysis In The Assessment Of The U.K. Wave Energy Programme, 1978
1.1 In a long term situation of rising energy prices convention al economic appraisal of energy technologies has a number of shortcomings. It is not possible to determine the inflationary effects of energy price rises on costs and also it is a very uncertain guide in R & D planning. By using energy analysis the energy element in costs and the inflationary effects of price rises can be determined directly . Also the net energy requirement is an index of merit which is available during the R & D phase and can be related theoretically to the economics of a technology. It provides a good indicator, during R & D, of economic potential. 1.2 The calculations reported here for wave energy systems are based mainly on information contained in RPT 1978 draft report and hence relate to the reference designs as then conceived. 1.3 The modal net energy requirements (energy input/energy output) for the 1978 Reference Designs on a primary energy basis are as follows National Engineering Laboratories (NEL) 2.79 GJâââ/GJâââ Wavepowe r Limited ( WPL) 1.45 GJâââ/GJâââ Hydraulics Research S t ation (HRS) 3.27 GJâââ/GJâââ Sea Energy Associates (SEA) 2.89 GJâââ/GJâââ French Flexible Bag (FFB) 0.46 GJâââ/GJâââ 1.4 On the basis of this information only the FFB satisfies the basic criteria of energetic viability. This criteria is that the net energy requirement of a wave energy system should be less than one. 1.5 While it is not possible as yet to establish the precise relationships between energy requirement and economic viability, clearly the 'energy returns' of the FFB are so low as to make it doubtful that this device would ever be economically viable in this form. 1.6 It is possible to model simply the relationship between energy requirements and costs. This indicates that a technology with a high energy requirement will suffer rapid cost inflation as energy prices rise. Depending on estimates of the value of output electricity (compared with the value of firm electricity) it seems that energy prices will have to rise 13 times before the FFB becomes economically viable. This is far beyond the limits of current medium term and even long-term planning horizons . l.7 It is difficult to imagine any realistic economic circumstances which may develop in the medium and long term which would make wave energy, in this form, economically viable. 1.8 To radically alter this assessment will r e quire a reduction in net energy requirement by factors ranging from 2.3 (FFB) to 16 (HRS). These improvements can only be achieved by substantial reductions in masses of structural and mooring materials per unit output together with improvements in the average load factor of all installed machinery. 1.9 Energy analysis raises serious questions about the wave energy programme. These must be answered convincingly before a rational case for committing major funds to the further development of these designs can be made. In particular the current emphasis on design for production would seem to be premature when basic problems of device size remain unresolved. 1.10 Further work is required constructing models of the net energy requirement of all devices in the prograrmme in terms of major system parameters (structural size, peak/average power ratings etc . ). Also energy analysis of new concepts and generic studies of wave energy devices is required. In this way established devices and new concept s will be analysed in a systematic way and it may be possible to identify directions of development which will offer the possibility of wave energy devices with low net energy requirements and with the ultimate potential to be economically viable
The therapeutic relationship in child psychotherapy: integrating the perspectives of children, parents and therapists
OBJECTIVES: To describe and analyse the therapeutic relationship integrating the views of children, parents and therapists. METHODS: This study employs a qualitative methodology, assuming a discovery-oriented approach which draws from grounded theory. Twelve psychotherapy triads participated, composed of children aged 6-10, their parents and psychotherapists. Semi-structured follow-up interviews were conducted (N=36), including a drawing in the case of the children. RESULTS: A positive therapeutic relationship with children and parents was viewed as a gradually constructed process, based on a positive emotional encounter between participants. It was facilitated primarily by the therapist's commitment and playful stance, the child and therapist mutual involvement, and the parent's collaboration. These aspects entailed a trustful, validating and caring relationship, that shaped children and parents' motivations towards therapy and facilitated change. CONCLUSIONS: From a multiple-perspective approach, therapy was conceived as a relational experience. The development of positive relationships required different and evolving dispositions from therapy main actors. Therapists' genuine feelings and engagement in therapeutic activity seem central, underlining the importance of addressing relational aspects in child therapy research and training
The missing piece of the South Atlantic jigsaw: when continental break-up ignores crustal heterogeneity
Crustal heterogeneity is considered to play a critical role in the position of continental break-up, yet this can only be demonstrated when a fully constrained pre-break-up configuration of both conjugate margins is achievable. Limitations in our understanding of the pre-break-up crustal structure in the offshore region of many margins preclude this. In the southern South Atlantic, which is an archetypal conjugate margin, this can be achieved because of the high confidence in plate reconstruction. Prior to addressing the role of crustal heterogeneity, two questions have to be addressed: first, what is the location of the regionally extensive Gondwanan Orogeny that remains enigmatic in the Orange Basin, offshore South Africa; and, second, although it has been established that the Argentinian Colorado rift basin has an eastâwest trend perpendicular to the Orange Basin and Atlantic spreading, where is the western continuation of this eastâwest trend? We present here a revised structural model for the southern South Atlantic by identifying the South African fold belt offshore. The fold belt trend changes from northâsouth to eastâwest offshore and correlates directly with the restored Colorado Basin. The ColoradoâOrange rifts form a tripartite system with the Namibian Gariep Belt, which we call the Garies Triple Junction. All three rift branches were active during the break-up of Gondwana, but during the Atlantic rift phase the Colorado Basin failed while the other two branches continued to rift, defining the present day location of the South Atlantic. In addressing these two outstanding questions, this study challenges the premise that crustal heterogeneity controls the position of continental break-up because seafloor spreading demonstrably cross-cuts the pre-existing crustal heterogeneity. Furthermore, we highlight the importance of differentiating between early rift evolution and subsequent rifting that occurs immediately prior to seafloor spreading
The Impact of Sexual Harassment on Depressive Symptoms during the Early Occupational Career
Sexual harassment has been theorized as a stressor with consequences for the physical and mental health of its targets. Although social scientists have documented a negative association between sexual harassment and mental health, few longitudinal studies have investigated the association between sexual harassment and depressive symptoms. Using longitudinal survey data from the Youth Development Study, combined with in-depth interviews, this article draws on Louise Fitzgeraldâs theoretical framework, stress theory, and the life course perspective to assess the impact of sexual harassment on depressive affect during the early occupational career. In support of Fitzgeraldâs model, the authorsâ findings confirm that sexual harassment is a stressor that is associated with increased depressive symptoms. Quantitative results show that women and men who experience more frequent sexual harassment at work have significantly higher levels of depressed mood than harassed workers, even after controlling for prior harassment and depressive symptoms. Moreover, the authors find evidence that sexual harassment early in the career has long-term effects on depressive symptoms in adulthood. Interviews with a subset of survey respondents point to a variety of coping strategies and reveal further links between harassment and other aspects of mental health, such as anger and self-doubt
Conceptual Profiles: Theoretical-methodological Grounds and Empirical Studies
AbstractIn this paper, we briefly address the theoretical and methodological grounds of the conceptual profile theory and discuss two empirical studies aiming at constructing conceptual profile models and using them to analyze classroom discourse in different sciences, chemistry (entropy and spontaneity) and biology (adaptation). The basic idea is to illustrate how these models were built, considering differences and similarities between the methods used for this purpose. Conceptual profiles are models of different modes of seeing and conceptualizing the world used by individuals to signify their experience. They are built for a given concept and are constituted by several zones, each representing a particular mode of thinking about that concept, related to a particular way of speaking. Each zone is individuated by ontological, epistemological, and axiological commitments underlying discourse. We will show how different concepts, situated in sciences with different levels of conceptual polysemy, demand different methodologies to deal with the variation found in meaning making in the sociocultural, ontogenetic, and microgenetic domains
Travel routes to remote ocean targets reveal the map sense resolution for a marine migrant
How animals navigate across the ocean to isolated targets remains perplexing greater than 150 years since this question was considered by Charles Darwin. To help solve this long-standing enigma, we considered the likely resolution of any map sense used in migration, based on the navigational performance across different scales (tens to thousands of kilometres). We assessed navigational performance using a unique high-resolution Fastloc-GPS tracking dataset for post-breeding hawksbill turtles (Eretmochelys imbricata) migrating relatively short distances to remote, isolated targets on submerged banks in the Indian Ocean. Individuals often followed circuitous paths (mean straightness index = 0.54, range 0.14-0.93, s.d. = 0.23, n = 22), when migrating short distances (mean beeline distance to target = 106 km, range 68.7-178.2 km). For example, one turtle travelled 1306.2 km when the beeline distance to the target was only 176.4 km. When off the beeline to their target, turtles sometimes corrected their course both in the open ocean and when encountering shallow water. Our results provide compelling evidence that hawksbill turtles only have a relatively crude map sense in the open ocean. The existence of widespread foraging and breeding areas on isolated oceanic sites points to target searching in the final stages of migration being common in sea turtles
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