Surface termination of CePt5/Pt(111): the key to chemical inertness

The surface termination of CePt5/Pt(111) is determined experimentally by LEED-IV. In accordance with recent theoretical predictions, a dense Pt terminated surface is being found. Whereas the CePt5 volume lattice comprises Pt kagome layers, additional Pt atoms occupy the associated hole positions at the surface. This finding provides a natural explanation for the remarkable inertness of the CePt5 intermetallic. Implications of the structural relaxations determined by LEED-IV analysis are discussed with regard to observations by scanning tunneling microscopy and electron spectroscopies.

Termination of diamond surfaces with hydrogen, oxygen and fluorine using a small, simple plasma gun

We have formed and characterized polycrystalline diamond films with surfaces having hydrogen terminations, oxygen terminations, or fluorine terminations, using a small, simple and novel plasma gun to bombard the diamond surface, formed by plasma assisted CVD in a prior step, with ions of the wanted terminating species. The potential differences between surface regions with different terminations were measured by Kelvin Force Microscopy (KFM). The highest potential occurred for oxygen termination regions and the lowest for fluorine. The potential difference between regions with oxygen terminations and hydrogen terminations was about 80 mV, and between regions with hydrogen terminations and fluorine terminations about 150 mV. Regions with different terminations were identified and imaged using the secondary electron signal provided by scanning electron microscopy (SEM). since this signal presents contrast for surfaces with different electrical properties. The wettability of the surfaces with different terminations was evaluated, measuring contact angles. The sample with oxygen termination was the most hydrophilic, with a contact angle of 75 degrees. hydrogen-terminated regions with 83 degrees, and fluorine regions 93 degrees, the most hydrophobic sample. (C) 2010 Elsevier B.V. All rights reserved.

Gait termination in young and older adults : effect of stopping stimulus probability and stimulus delay

Sixteen young (25±2.6 years) and 16 older individuals (69±4.4 years) walked normally then terminated walking rapidly. A visual stopping stimulus was presented 10 ms following ground contact (short delay) and in another condition, at 450 ms prior to toe-off (long delay). Stimulus probability was either high (80% of trials) or low (10%). The younger group stopped faster (463 vs. 574 ms) despite also walking faster (1.29 vs. 1.17 m s⁻¹). Longer delay decreased one-step responses but older participants used significantly more (slower) two-step stopping, which increased stopping time and distance. The additional step may have been pre-planned to maintain medial–lateral stability.

Gait termination : a review of experimental methods and the effects of aging and gait pathologies

The study of human gait has expanded and diversified to the extent that it is now possible to identify a substantive literature concerning a variety of gait tasks, such as gait initiation [Halliday SE, Winter DA, Frank JS, Patla AE, Prince F. The initiation of gait in young, elderly, and Parkinson's disease subjects. Gait Posture 1998;8:8–14; Mickelborough J, van der Linden ML, Tallis RC, Ennos AR. Muscle activity during gait initiation in normal elderly people. Gait Posture 2004;19:50–57], stepping over and across obstacles [Patla AE, Prentice SD, Robinson C, Newfold J. Visual control of locomotion: strategies for changing direction and for going over obstacles. J Exp Psych 1991;17:603–34; Chen, HC, Ashton-Miller JA, Alexander NB, Schultz AB. Effect of age and available response time on ability to step over an obstacle. J Gerontol 1994;49:227–33; Sparrow WA, Shinkfield AJ, Chow S, Begg RK. Gait characteristics in stepping over obstacles. Hum Mov Sci 1996;15:605–22; Begg RK, Sparrow WA, Lythgo ND. Time-domain analysis of foot–ground reaction forces in negotiating obstacles. Gait Posture 1998;7:99–109; Patla AE, Rietdyk S. Visual control of limb trajectory over obstacles during locomotion: effect of obstacle height and width. Gait Posture 1993;1:45–60] negotiating raised surfaces such as curbs and stairs [Begg RK, Sparrow WA. Gait characteristics of young and older individuals negotiating a raised surface: implications for the prevention of falls. J Gerontol Med Sci 2000;55A:147–54; Mcfayden BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech 1988;21:733–44]. In addition, increasing research interest in age-related declines in gait that might predispose individuals to falls has engendered a very extensive literature concerning ageing effects on gait. While rapid locomotor adjustments are common in the course of daily activities there has been no previous review of the findings concerning gait adaptations when walking is terminated both rapidly and unexpectedly. The aims of this review were first, to summarise the key research findings and methodological considerations from studies of termination. The second aim was to demonstrate the effects of ageing and gait pathologies on termination with respect to the regulation of step characteristics, lower-limb muscle activation patterns and foot–ground reaction forces.

Age and walking speed effects on muscle recruitment in gait termination

During gait termination at normal walking speed, older adults more frequently employ two-step responses, increasing their stopping distance and stopping time more than younger controls. This study investigated ageing effects on lower limb muscle recruitment patterns during stopping at three walking speeds. Twelve young male (26±3.7 years, range 19–30) and 12 gender-matched older participants (72±4.3 years, range 65–82) terminated walking at normal, medium and maximum speed. A visual stopping stimulus was presented 10 ms following either left or right heel-contact with no stimulus (catch) on 30% of trials. Electromyographic (EMG) activity was recorded from the tibialis anterior (TA), soleus (SOL), biceps femoris (BF), vastus lateralis (VL) and gluteus medius (GM). Older males more frequently (46% of trials) took two-steps to stop than young males (20%). The stance leg muscles responded significantly faster than the swing leg, and with increased speed, fewer swing limb muscles contributed to stopping. Older males were slower to respond with the stance leg, at 215 ms following the stimulus compared with 176 ms for the younger group. They also recruited fewer swing leg muscles with less frequent activation of the soleus and gluteus medius. Failure to activate muscles would provide less extensor torque to maintain the centre of gravity anterior to the forward base of support. This would decrease the total force opposing horizontal velocity in order to bring the body to rest and, as a consequence, encourage an additional step prior to stopping.

Intention to claim a Medicare rebate among women receiving private Victorian pregnancy termination service

Objectives: To determine the proportion of women who have pregnancy terminations as private patients in Victoria who do not intend to claim a procedure fee rebate from Medicare, to compare characteristics of women who intend to submit a Medicare claim with those who do not and to compare the findings to the results from a similar study conducted in NSW in 1992.

Design, setting and participants: This was a cross-sectional observational study over a 12-week period. Women having a pregnancy termination service in eight large Victorian private clinics were invited to complete a brief written questionnaire.

Outcome measurer: The proportion of women who did not have a Medicare card or who had a Medicare card but did not intend to use it to claim from Medicare.

Results: Of the 1,329 women who responded, 13.1% either did not have a Medicare card or did not intend to use their card to claim a Medicare rebate. A further 20.7% of respondents were not sure about whether they would submit a claim. Women who intended to claim a Medicare rebate were different from women who did not according to age, language spoken at home, residency, citizenship and distance travelled to the service. These results are very similar to the findings from the 1992 NSW study.

Conclusion: Between 13.1% and 33.8% of private Victorian pregnancy terminations were estimated to not be recorded at the Health Insurance Commission. Health Insurance Commission records of Medicare rebate claims for pregnancy terminations are an incomplete and somewhat biased record of the services that are provided and are likely to have been so for some time.

Travel undertaken by women accessing private Victorian pregnancy termination services

Objective: To investigate the extent and cost of travel undertaken by women accessing Victorian termination of pregnancy services.

Design, setting and participants: This was a multi-centre, cross-sectional observational study of women receiving privately funded pregnancy termination services, conducted between November 2002 and June 2003 at eight major pregnancy termination service providers in Victoria.

Main outcome measures: Distance travelled, money and time expended undertaking travel, and reasons women chose particular clinics.

Results: Of the 1,244 Australian resident respondents who resided in Victoria, 9.3% travelled more than 100 km to access services. Teenagers were 2.5 times more likely than other respondents to travel further than 100 kilometres (km) (18.2% compared with 7.8%, OR=2.5, 95% CI 1.5-4.2, p<0.001). Women originated from all Australian States and Territories except South Australia and 13.7% were from Statistical Divisions other than Melbourne. More than one-third of respondents (41.3%) chose their clinic because they were referred by a doctor or general practitioner.

Conclusion: Many pregnancy termination patients face substantial and immediate costs beyond the service fee, as well as the diffculties associated with poor continuity of care and signifcant time away from home. Patients and service providers should be consulted further to determine appropriate clinical services, support services and subsidy schemes for the sizeable proportion of patients who undertake long-distance travel to access pregnancy termination services.

Understanding endings : evaluation and termination

In this chapter, issues related to practice evaluation and termination of client contact are covered. The chapter begins by discussing the rationale for evaluating practice, followed by an outline of differing types of evaluation procedures. The second part of the chapter focuses on the expected and unexpected ways in which clients and workers may draw their professional contact to a close. Students will be asked to complete an exercise that will demonstrate an understanding of the Integrated Framework outlined in Chapter 1 and referred to throughout the text.

Independent functions of yeast Pcf11p in pre-mRNA 3´ end processing and in transcription termination

Pcf11p, an essential subunit of the yeast cleavage factor IA, is required for pre-mRNA 3' end processing, binds to the C-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAP II) and is involved in transcription termination. We show that the conserved CTD interaction domain (CID) of Pcf11p is essential for cell viability. Interestingly, the CTD binding and 3' end processing activities of Pcf11p can be functionally uncoupled from each other and provided by distinct Pcf11p fragments in trans. Impaired CTD binding did not affect the 3' end processing activity of Pcf11p and a deficiency of Pcf11p in 3' end processing did not prevent CTD binding. Transcriptional run-on analysis with the CYC1 gene revealed that loss of cleavage activity did not correlate with a defect in transcription termination, whereas loss of CTD binding did. We conclude that Pcf11p is a bifunctional protein and that transcript cleavage is not an obligatory step prior to RNAP II termination.

Yhh1p/Cft1p directly links poly(A) site recognition and RNA polymerase II transcription termination

RNA polymerase II (pol II) transcription termination requires co-transcriptional recognition of a functional polyadenylation signal, but the molecular mechanisms that transduce this signal to pol II remain unclear. We show that Yhh1p/Cft1p, the yeast homologue of the mammalian AAUAAA interacting protein CPSF 160, is an RNA-binding protein and provide evidence that it participates in poly(A) site recognition. Interestingly, RNA binding is mediated by a central domain composed of predicted -propeller-forming repeats, which occurs in proteins of diverse cellular functions. We also found that Yhh1p/Cft1p bound specifically to the phosphorylated C-terminal domain (CTD) of pol II in vitro and in a two-hybrid test in vivo. Furthermore, transcriptional run-on analysis demonstrated that yhh1 mutants were defective in transcription termination, suggesting that Yhh1p/Cft1p functions in the coupling of transcription and 3'-end formation. We propose that direct interactions of Yhh1p/Cft1p with both the RNA transcript and the CTD are required to communicate poly(A) site recognition to elongating pol II to initiate transcription termination.