Vacuum-UV negative photoion spectroscopy of CH3F, CH3Cl and CH3Br

Using tunable vacuum-UV radiation from a synchrotron, negative ions are detected by quadrupolar mass spectrometry following photoexcitation of three gaseous halogenated methanes CH$_3$X (X = F,Cl,Br). The anions X$^-$, H$^-$, CX$^-$, CHX$^-$ and CH$_2$X$^-$ are observed, and their ion yields recorded in the range 8-35 eV. The anions show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation, generically described as AB + h$v$ $\rightarrow$ A$^-$ + B$^+$ (+ neutrals). Absolute cross sections for ion-pair formation are obtained by calibrating the signal intensities with those of F$^-$ from both SF$_6$ and CF$_4$. The cross sections for formation of X$^-$ + CH$_3$$^+$ are much greater than for formation of CH$_2$X$^-$ + H$^+$. In common with many quadrupoles, the spectra of $m$/$z$ 1 (H$^-$) anions show contributions from all anions, and only for CH$_3$Br is it possible to perform the necessary subtraction to obtain the true H$^-$ spectrum. The anion cross sections are normalised to vacuum-UV absorption cross sections to obtain quantum yields for their production. The appearance energies of X$^-$ and CH$_2$X$^-$ are used to calculate upper limits to 298 K bond dissociation energies for D$^o$ (H$_3$C-X) and D$^o$ (XH$_2$C-H) which are consistent with literature values. The spectra suggest that most of the anions are formed indirectly by crossing of Rydberg states of the parent molecule onto an ion-pair continuum. The one exception is the lowest-energy peak of F$^-$ from CH$_3$F at 13.4 eV, where its width and lack of structure suggest it may correspond to a direct ion-pair transition

Relationship between the learning styles preferences and academic achievement

The individual learning differences that have been much explored relate to differences in personality, learning styles, strategies and conceptual of learning. This article studies the learning style profile exhibited by students towards the academic achievement in Malaysian Polytechnic. The relationship between learning styles of Polytechnic students and their academic achievement based on VARK learning styles model. The target population was international business students of Malaysian Polytechnic. By means of randomly sampling method, 103 students were selected as sample of research. By descriptive - survey research method and a questionnaire adapted from VARK Learning Style Index, required data were collected. According to the results, no significantly difference between learning style and academic achievement of students. Students academic achievement was quite similar to their individual learning styles. These facts reveal that each learning style has its own strengths and weaknesses

Hip and knee arthroplasty waiting list – how accurate and fair?

Background. Resource-intensive procedures require the use of patient waiting lists in an attempt to increase fairness of access to surgery and improve surgical efficiency. Total hip and knee arthroplasty has waiting lists in excess of years. Objectives. To analyse our tertiary state institution’s hip and knee arthroplasty waiting list to assess its accuracy.Methods. At Groote Schuur Hospital, our hospital-maintained database was compared with the surgeons’ personally maintained database. Patients were then telephoned to confirm their contactability, and to discover whether they still wanted the procedure, or if they had already had it. Waiting duration and patient demographics were then calculated.Results. Of the 655 patients on the hospital waiting list, only 454 were contactable. Three hundred and nine patients still wanted the surgery, 93 had already undergone surgery and 52 no longer wanted surgery. The last group was the oldest and had had the longest waiting time. Those still waiting had waited 451 days (minimum - maximum (standard deviation), 90 - 1 593 (228.5)), those that had had surgery 371 days (0 - 1 728 (296)) and those no longer interested 523 days (138 - 1 881 (260.9)). A total of 429 patients were present on the surgeons’ list but not on the hospital list. They had had longer waiting times than those on the hospital list.Conclusion. The arthroplasty waiting list is inaccurate due to the existence of two concurrent lists and poor data management, particularly of current contact details. The unfairness of a wide range of waiting times was identified, with patients only on the surgeons’ personal database disadvantaged. These deficiencies have prompted the introduction of  a scoring-based prioritisation system incorporating clinical, radiographic and societal parameters, in an effort to improve fair and appropriate access to this high-cost care

Gunshot injuries of the spine

The Acute Spinal Injury Unit, relocated from Conradie Hospital to Groote Schuur Hospital in mid-2003, admitted 162 patients in the first year of its existence. A large number of these injuries were the result of interpersonal violence, particularly gunshot wounds. Aim. To review patients with gunshot injuries to the spine, with reference to neurological injury, associated injuries, need for surgery and complications. Methods. A comprehensive database is maintained to collect data on all spinal injury admissions. These data, as well as case notes and X-rays, were reviewed for all gunshot spine patients admitted to the Acute Spinal Injury Unit over a year. Forty-nine patients were identified. Thirty-eight were male and 11 female with an average age of 27.5 years (range 15 - 51 ± 8.53). The average stay in the acute unit was 30 (4 - 109 ± 28) days. Results. The spinal injury was complete in 38 and incomplete in 8, with 3 having no neurological deficit. The level was cervical in 13, thoracic in 24 and lumbar in 12. Only 9 patients improved neurologically. The spine was considered stable in 43 cases. Stabilisation was performed in the 6 unstable cases. The bullets were removed in 11 cases as they were in the canal. There were 55 significant associated injuries, viz. 14 haemo-pneumothoraces, 16 abdominal visceral injuries, 3 vascular injuries, 4 injuries of the brachial plexus and 3 of the oesophagus, 2 tracheal injuries, 1 soft palate injury and 11 non-spinal fractures. Complications included 3 deaths and discitis in 3 cases, pneumonia in 6 and pressure sores in 6. Conclusion. Gunshot injuries of the spine are a prevalent and resource-intensive cause of paralysis. There is a high incidence of permanent severe neurological deficit, but usually the spine remains mechanically stable. Most of the management revolves around the associated injuries and consequences of the neurological deficit

Hip and knee arthroplasty waiting list – how accurate and fair?

Background. Resource-intensive procedures require the use of patient waiting lists in an attempt to increase fairness of access to surgery and improve surgical efficiency. Total hip and knee arthroplasty has waiting lists in excess of years. Objectives. To analyse our tertiary state institution’s hip and knee arthroplasty waiting list to assess its accuracy. Methods. At Groote Schuur Hospital, our hospital-maintained database was compared with the surgeons’ personally maintained database. Patients were then telephoned to confirm their contactability, and to discover whether they still wanted the procedure, or if they had already had it. Waiting duration and patient demographics were then calculated. Results. Of the 655 patients on the hospital waiting list, only 454 were contactable. Three hundred and nine patients still wanted the surgery, 93 had already undergone surgery and 52 no longer wanted surgery. The last group was the oldest and had had the longest waiting time. Those still waiting had waited 451 days (minimum - maximum (standard deviation), 90 - 1 593 (228.5)), those that had had surgery 371 days (0 - 1 728 (296)) and those no longer interested 523 days (138 - 1 881 (260.9)). A total of 429 patients were present on the surgeons’ list but not on the hospital list. They had had longer waiting times than those on the hospital list. Conclusion. The arthroplasty waiting list is inaccurate due to the existence of two concurrent lists and poor data management, particularly of current contact details. The unfairness of a wide range of waiting times was identified, with patients only on the surgeons’ personal database disadvantaged. These deficiencies have prompted the introduction of a scoring-based prioritisation system incorporating clinical, radiographic and societal parameters, in an effort to improve fair and appropriate access to this high-cost care

Epidemiology of acute spinal cord injuries in the Groote Schuur Hospital Acute Spinal Cord Injury (GSH ASCI) Unit, Cape Town, South Africa, over the past 11 years

Background. Spinal cord injury (SCI) is devastating to both patient and society, with acute management and ongoing care being extremely expensive. Few epidemiological data are available on SCIs in South Africa (SA).Objectives. To identify the epidemiological profile of SCI patients at Groote Schuur Hospital (GSH), Cape Town, SA, and identify seasonal trends and peak periods. As the majority of the injuries are preventable, these data are important to develop prevention strategies. Methods. A retrospective review of prospectively collected data was conducted on all patients admitted to the Acute Spinal Cord Injury (ASCI) Unit at GSH from 1 April 2003 to 31 March 2014. All cases registered on a prospectively maintained database were included in the study.Results. The total number of patients admitted to the ASCI Unit was 2 042, with an average of 185 admissions per year. The male/female ratio was 5.25:1. The 21 - 30-year-old age category was the largest, comprising 33.5% of the patients. The most prevalent cause of injury was motor vehicle accidents (44.6%), followed by violence-related injuries (27.2%). Thirty-two point two percent of patients needed ventilatory support, and 91.5% of mechanically ventilated patients were successfully weaned. December was the busiest month in the unit. In patients in whom neurological deficit was incomplete, the average motor function improvement was 16.0%.Conclusions. Data capturing and analysis of SCIs should be encouraged in SA to guide management and prevention strategies, and to optimise outcomes. This study establishes the ASCI Unit at GSH to be one of the key role players in acute SCI management in SA

Avatars:the other side of Proteus's mirror : a study into avatar choice regarding perception

The trend for online interactions, can be regarded as being ‘anti-so-cially social’, meaning that a great deal of time is spent playing, working and socializing with the internet serving as the communication conduit. Within that Virtual Social Environment very deep relationships are formed and maintained without the parties ever having met each other face-to-face. Raising the question how much does the physical appearance of an avatar influence the perception of the person behind it? Are relationships informed by appearance even in the vir-tual world and what implications does that have for second language acquisition? This paper leads to a small-scale research project where a selection of avatars with various racially identifiable characteristics were used to identify which av-atars a second language speaker would feel more at ease interacting with in the target language. The resultant research aims to test three hypotheses regarding preferred avatar choice for second language users based solely on perceptions

Histone Hypervariants H2A.Z.1 and H2A.Z.2 Play Independent and Context-Specific Roles in Neuronal Activity-Induced Transcription of Arc/Arg3.1 and Other Immediate Early Genes.

The histone variant H2A.Z is an essential and conserved regulator of eukaryotic gene transcription. However, the exact role of this histone in the transcriptional process remains perplexing. In vertebrates, H2A.Z has two hypervariants, H2A.Z.1 and H2A.Z.2, that have almost identical sequences except for three amino acid residues. Due to such similarity, functional specificity of these hypervariants in neurobiological processes, if any, remain largely unknown. In this study with dissociated rat cortical neurons, we asked if H2A.Z hypervariants have distinct functions in regulating basal and activity-induced gene transcription. Hypervariant-specific RNAi and microarray analyses revealed that H2A.Z.1 and H2A.Z.2 regulate basal expression of largely nonoverlapping gene sets, including genes that code for several synaptic proteins. In response to neuronal activity, rapid transcription of our model gene Arc is impaired by depletion of H2A.Z.2, but not H2A.Z.1. This impairment is partially rescued by codepletion of the H2A.Z chaperone, ANP32E. In contrast, under a different context (after 48 h of tetrodotoxin, TTX), rapid transcription of Arc is impaired by depletion of either hypervariant. Such context-dependent roles of H2A.Z hypervariants, as revealed by our multiplexed gene expression assays, are also evident with several other immediate early genes, where regulatory roles of these hypervariants vary from gene to gene under different conditions. Together, our data suggest that H2A.Z hypervariants have context-specific roles that complement each other to mediate activity-induced neuronal gene transcription