Investigation of co-travelling solitary wave collisions in a granular chain

We present investigations into the collision of co-travelling solitary waves in a granular chain. Impulses are injected into the system by means of a piezo stack and the results are compared to a numerical model of discrete masses connected by non-linear springs. Similar to other solitary wave-carrying systems, a phase shift in both interacting solitary waves is observed due to their collision. Additionally, the formation of small secondary waves is observed in both numerical and experimental results. Insight into solitary wave interactions will be important for high-frequency excitation of a granular crystal, which may allow for improved Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) methods

Extending Syncom 3\u27s Orbital Life Over the Pacific

Syncom 3, launched in August 1964, was the first satellite to be maneuvered to a nearstationary orbit. It is presently functioning as an essential communication link between Hawaii and the Far East, As long as the satellite remains within mutual visibility of these areas, this link will continue to exist. Ironically, the by-product of an unwanted process, namely, gas resulting from decomposition of the propellant (hydrogen peroxide) which was originally intended to provide orbital control, is now being used to maintain this link. If the satellite orbit were not controllable, Syncorn 3 would drift out of the mutual visibility longitude band as a result of forces exerted by the earth\u27s triaxiality, The unstable equilibrium longitude in the Pacific, computed to be at 162.4 °E, lies within this band. Near this point, the control velocity requirements are small, so that minimal control capability, such as is available from the gas, could extend Syncom 3\u27s orbital life for as much as 10 years. This is unlikely, however, because of the degraded condition of the batteries which are essential for operation of the control jets. The satellite on its present drift trajectory should remain visible from Hawaii until early 1969. Longitudinal control of Syncom 3 in the vicinity of the Pacific equilibrium longitude has now been accomplished with gas for approximately 1.5 years. The specific impulse observed is approximately 57.1 seconds. The mass flow rates observed have resulted in velocity increments of about 0.005 fps per pulse, Such high resolution is required to maintain the satellite position close to but west of the equilibrium longitude. This constraint is based on the increased, visibility time for westerly drift in case of complete loss or depletion of control capability. Since the batteries are weak and gas leaks are to be expected in a system not originally designed for use of gas, such a constraint is reasonable

Regulating organizational identity in temporary organizations

Organizational identity refers to the central, distinct, and enduring features that define ‘who we are’ and ‘what we do’ as an organization. Extant scholarship posits that organizations use historical referents and projected futures to construct identity in the present; however, it is not yet known how organizational identity is formed when organizations are project-based or otherwise temporary in nature. This thesis addresses this research gap by exploring how a temporary arts organization formed aligned identity understandings without an internal past or anticipated future. This thesis is grounded in a three-year, qualitative study of the ‘City of Culture Trust’ (CCT) a temporary arts organization. Data consists of 103 interviews and178 hours of observation. Data is presented that shows how managers constructed formal identity claims through which they hoped to shape the identity understandings of organizational members. Justified though the expediency required by temporary organizations, managers also established a system of sensechecking – a process induced within this research – through which managers evaluated whether organizational members developed identity understandings congruent with manager-derived identity claims. By rewarding aligned understandings and admonishing misalignment, organizational managers were able to quickly regulate how members viewed the organization’s identity. However, this regulation process was not always successful. To explain why this is the case, additional research is recounted that explored how workers paid attention to different cues when they made sense of the organization’s identity. Worker sensemaking was either goal-attentive (whereby workers focused on ‘who we are’ as an organization) or operation-attentive (whereby workers focused on ‘what we do’ as an organization). Workers who engaged in both goal-attentive and operation-attentive sensemaking were able to develop identity understandings aligned with CCT managers, while workers who engaged extensively in goal-attentive sensemaking but not operation-attentive sensemaking were unable to do so. In total, this thesis provides several contributions to the scholarship of organizational identity and sensemaking. First, this thesis posits that organizational identity can be constructed vis-à-vis regulation rather than historical positioning. A theoretical model for organizational identity regulation in temporary organizations is put forward. Moreover, while previous literature has characterized the emergence of organizational identity as collaborative and organic, this regulation model complicates this core conception. Second, while extant literature posits that individuals extract and interpret cues from their environment to ‘make sense’ of ambiguous stimuli, this thesis expands this conceptualization to define two specific types of sensemaking attention relevant to interpreting organizational identity: goal-attentive and operation-attentive. Moreover, sense-shaping efforts related to organizational identity must address both types of sensemaking in order to ensure that workers develop aligned identity understandings

The evaluation of a school-based substance abuse prevention programme

This research report presents the findings of an evaluation of a school-based substance abuse prevention programme presented as part of Project Awareness. The programme was presented as a one-day intervention for grade ten learners in eleven schools in Tshwane. The prevention program taught substance abuse refusal skills, anti-substance norms, personal self-management skills, and general social skills in an effort to provide students with skills and information for resisting substance offers, to decrease motivations to use substances, and decrease vulnerability to substance use social influences. The study evaluated this school-based substance abuse prevention intervention in a sample of learners (N=300) in six of the eleven schools. Measures were obtained on a behavioural survey to ascertain whether any knowledge, behaviour or attitude change occurred between the pre-intervention and post-intervention phases. In addition, focus group data and observational measures were implemented to determine how the learners experienced the programme and whether the programme was effective in capturing the attention of the learners. Results indicated that, from learners perceptions of the programme, the intervention seems to have had a positive impact on substance abuse prevention, but not on changing the behaviour of learners already engaging in substance abuse. The results from the behavioural survey indicated some change in learner attitudes to some degree, but not behavioural change. Suggestions for the improvement of the programme were made throughout the report, and the observational measures specifically indicated that the more practical oriented tasks were more efficient in capturing the attention of learners. It is concluded that although the programme certainly had room for improvement, that the programme did indeed address relevant issues. The program also had a direct positive effect on several cognitive, attitudinal, and personality variables believed to play a role in adolescent substance use.Dissertation (MA)--University of Pretoria, 2008.Psychologyunrestricte

Pendidikan Kesehatan Breast Self Examination (BSE) Berpengaruh terhadap Perilaku pada Remaja Putri KELAS XII

Perilaku merupakan respon seseorang terhadap stimulus yang dapat dilihat dari diri seseorang tersebut. Perilaku terdiri dari 3 domain, yaitu: pengetahuan, sikap, dan praktik. Breast self examination (BSE) adalah metode yang paling mudah dan hemat biaya untuk mendiagnosis kanker payudara secara dini. Pendidikan kesehatan tentang pemeriksaan payudara sendiri bersifat menginformasikan kepada remaja putri tentang cara deteksi dini kanker payudara. Metode: pre-eksperimental dengan one group pre-post test design. Populasi pada penelitian ini sebanyak 121 orang, di mana teknik pengambilan sampel dengan purposive sampling pada 45 responden. Hasil: Perilaku remaja putri pre test diberikan pendidikan kesehatan BSE disimpulkan perilaku kurang sebanyak 37 responden (82.2%) dari 45 responden dan pada post test terjadi peningkatan menjadi perilaku cukup sebanyak 21 responden (46.7%) dari 45 responden. Pembahasan: Analisa data dengan uji wilcoxon sign rank test diperoleh nilai p=0,001 dimana p<0,05. Kesimpulan: Ada pengaruh pendidikan kesehatan BSE terhadap perilaku pada remaja putri kelas XII di SMA Swasta Sultan Agung kota Pematangsiantar

The effect of in vitro digestion on selected biological activities of Hypoxis sobolifera corms

In South Africa part of the cultural and religious beliefs of the African people is the use of traditional remedies to treat diseases. These remedies are obtained from medicinal plants (Steenkamp, 2003). One of the most frequently traded plants in the Eastern Cape is Hypoxis, commonly known as Afrika patat, or African potato. South African traditional healers instruct patients to brew the fresh Hypoxis corm as a tea and then ingest it (Steenkamp, 2006a). This prompted an investigation into the digestive stability of a traditionally prepared Hypoxis extract. The H. sobolifera extracts were digested using a simulated gastric/small intestinal digestion and their biological activity determined. The hot water H. sobolifera extract before digestion only showed cytotoxic activity against cancer cell lines at very high concentrations which are not likely to be achieved under normal ingestion circumstances. In Chang liver cells on the other hand, chronic exposure to the hot water H. sobolifera extract increased glucose uptake in amounts similar to that of metformin. On the negative side, the glucose utilization stimulation was lost due to the simulated digestion process. The significant inhibition of AGEs by hot water H. sobolifera extract (IC50 of 6.3 Ig/ml) is a very encouraging result as treatment in the management of diabetes. This activity was only slightly reduced by the in vitro digestion process. Also observed was enzyme inhibition activity by traditionally prepared H. sobolifera, with ∝-amylase being inhibited (IC50 of approximately 250 Ig/ml) and therefore preventing or limiting starch breakdown. From the DPPH results it was clear that H. sobolifera, even when digested, is a potent anti-oxidant (IC50 of 134.4 Ig/ml when undigested compared to 162.9 when digested with β-glucosidase added to stomach digestive step). HPLC and TLC experiments revealed that rooperol which has previously been thought to be the compound responsible for the anti-oxidant activity in Hypoxis extracts, was absent from the traditional extract of H. sobolifera and therefore cannot be the sole compound exhibiting anti-oxidant activity; other compounds such as phenolics may be contributing. The phenolic and flavonoid content results revealed very highconcentrations of these compounds in the traditionally prepared H. sobolifera extract. These compounds may therefore play major roles in all of the biological activities observed from treatment with Hypoxis spp. The ROS results yielded interesting and promising results. Using standard or traditionally prepared H. sobolifera extracts, activation of differentiated U937 cells with PMA was greatly enhanced by cotreatment with the extracts, while extracts on their own did not cause significant activation. Future studies should investigate this property of the extracts as a promising immune boosterThe HPLC results showed that hypoxoside was undetectable in the hot water traditional extract and the TLC anti-oxidant experiment proved that rooperol is not present in the hot water traditional extract after treatment with β-glucosidase. This indicates that neither one of the Hypoxis compounds previously believed to be responsible for the biological activities observed are present in the extract when prepared the traditional way. Therefore, the biological activities observed in this study can be attributed to other phytochemical compounds

Gold in the past, today and future

This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today's value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics manufacturing and the synthesizing of different functional materials. It is important that we know that gold is also used in industry in many engineering applications (contacts in micro-electronics) and medicine (dental alloys, implants)

External atmospheric influences on the mechanical properties of resin-bonded grinding wheels with aluminium oxide and silicon carbide grains

Ageing effects on resin-bonded grinding wheel properties are presented, including aluminium oxide and silicon carbide influence. Furthermore, humidity is examined as the most likely cause of significant downgrade in mechanical properties. Toward this aim a new system of accelerated ageing of grinding wheels (additional humidification) is used under special atmospheric conditions. The mechanisms for microstructural changes during ageing are analysed, based on the microstructure exposure to thermo-mechanical impacts

External atmospheric influences on the mechanical properties of resin-bonded grinding wheels with aluminium oxide and silicon carbide grains

Ageing effects on resin-bonded grinding wheel properties are presented, including aluminium oxide and silicon carbide influence. Furthermore, humidity is examined as the most likely cause of significant downgrade in mechanical properties. Toward this aim a new system of accelerated ageing of grinding wheels (additional humidification) is used under special atmospheric conditions. The mechanisms for microstructural changes during ageing are analysed, based on the microstructure exposure to thermo-mechanical impacts

Repumping and spectroscopy of laser-cooled Sr atoms using the (5s5p)3P2 - (5s4d)3D2 transition

We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p)3P2 - (5s4d)3D2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p)3P2 dark state are repumped back into the (5s2)1S0 ground state. Spectroscopy of 84Sr, 86Sr, 87Sr, and 88Sr improves the value of the (5s5p)3P2 - (5s4d)3D2 transition frequency for 88Sr and determines the isotope shifts for the transition.Comment: 4 pages, 5 figure