Toward a script theory of guidance in computer-supported collaborative learning

This article presents an outline of a script theory of guidance for computer-supported collaborative learning (CSCL). With its four types of components of internal and external scripts (play, scene, role, and scriptlet) and seven principles, this theory addresses the question how CSCL practices are shaped by dynamically re-configured internal collaboration scripts of the participating learners. Furthermore, it explains how internal collaboration scripts develop through participation in CSCL practices. It emphasizes the importance of active application of subject matter knowledge in CSCL practices, and it prioritizes transactive over non-transactive forms of knowledge application in order to facilitate learning. Further, the theory explains how external collaboration scripts modify CSCL practices and how they influence the development of internal collaboration scripts. The principles specify an optimal scaffolding level for external collaboration scripts and allow for the formulation of hypotheses about the fading of external collaboration scripts. Finally, the article points towards conceptual challenges and future research questions

Detection of very-high-energy gamma-ray emission from the vicinity of PSR B1706-44 with H.E.S.S

The energetic pulsar PSR B1706-44 and the adjacent supernova remnant (SNR) candidate G 343.1-2.3 were observed by H.E.S.S. during a dedicated observational campaign in 2007. A new source of very-high-energy (VHE; E > 100 GeV) gamma-ray emission, HESS J1708-443, was discovered with its centroid at RA(J2000) = 17h08m10s and Dec(J2000) = -44d21', with a statistical error of 3 arcmin on each axis. The VHE gamma-ray source is significantly more extended than the H.E.S.S. point-spread function, with an intrinsic Gaussian width of 0.29 +/- 0.04 deg. Its energy spectrum can be described by a power law with a photon index Gamma = 2.0 +/- 0.1 (stat) +/- 0.2 (sys). The integral flux measured between 1-10 TeV is ~17% of the Crab Nebula flux in the same energy range. The possible associations with PSR B1706-44 and SNR G343.1-2.3 are discussed.Comment: 4+ pages, 2 figures; v1 submitted to ICRC Proceedings on 15 May 2009; v2 has additional references and minor change

Electrostatic colloid-membrane complexation

We investigate numerically and on the scaling level the adsorption of a charged colloid on an oppositely charged flexible membrane. We show that the long ranged character of the electrostatic interaction leads to a wrapping reentrance of the complex as the salt concentration is varied. The membrane wrapping depends on the size of the colloid and on the salt concentration and only for intermediate salt concentration and colloid sizes we find full wrapping. From the scaling model we derive simple relations for the phase boundaries between the different states of the complex, which agree well with the numerical minimization of the free energy.Comment: 7 page, 11 figure

Improved constraints from ultra-faint dwarf galaxies on primordial black holes as dark matter

Soon after the recent first ever detection of gravitational waves from merging black holes it has been suggested that their origin is primordial. Appealingly, a sufficient number of primordial black holes (PBHs) could also partially or entirely constitute the dark matter (DM) in the Universe. However, recent studies on PBHs in ultra-faint dwarf galaxies (UFDGs) suggest that they would dynamically heat up the stellar component due to two-body relaxation processes. From the comparison with the observed stellar velocity dispersions and the stellar half-light radii it was claimed that only PBHs with masses $\lesssim10\,M_\odot$ can significantly contribute to the DM. In this work, we improve the latter constraints by considering the largest observational sample of UFDGs and by allowing the PBH masses to follow an extended (log-normal) distribution. By means of collisional Fokker-Planck simulations, we explore a wide parameter space of UFDGs containing PBHs. The analysis of the half-light radii and velocity dispersions resulting from the simulations leads to three general findings that exclude PBHs with masses $\sim\mathcal{O}(1$-$100)\,M_\odot$ from constituting all of the DM: (i) We identify a critical sub-sample of UFDGs that only allows for $\sim\mathcal{O}(1)\,M_\odot$ PBH masses; (ii) for any PBH mass, there is an UFDG in our sample that disfavours it; (iii) the spatial extensions of a majority of simulated UFDGs containing PBHs are too large to match the observed

Role of a Transbilayer pH Gradient in the Membrane Fusion Activity of the Influenza Virus Hemagglutinin: Use of the R18 Assay to Monitor Membrane Merging

It had been suggested that influenza virus-mediated membrane fusion might be dependent on a pH gradient across a target membrane. We have designed experiments in which this issue could be addressed. Two populations of liposomes were prepared, both simulating the plasma membrane of target cells, but with the pH of the internal aqueous medium buffered either at pH 7.4 (physiological cytosol pH) or at pH 5.0 (endosomal pH at which influenza virus displays maximal fusion activity). By monitoring fusion using the R18 assay, we found that the internal pH of the target liposomes did not influence membrane merging as mediated by the influenza virus hemagglutinin, thus demonstrating that a transmembrane pH gradient is not required in this fusion process

Hospital postdischarge intervention trialled with family caregivers of older people in Western Australia: potential translation into practice

There is lack of a suitable assessment tool that can be used routinely and systematically by hospital staff to address family caregivers' (FCs') support needs. This paper describes a novel approach to identifying and addressing FCs' needs following hospital discharge of the older person receiving care. SETTING AND PARTICIPANTS: FC recruitment occurred on the patient's discharge from a tertiary hospital in Western Australia; 64 completed the study; 80% were female; mean age 63.2 years. INTERVENTION: The Further Enabling Care at Home (FECH) programme was delivered over the telephone by a specially trained nurse and included: support to facilitate understanding of the patient's discharge letter; caregiver support needs assessment and prioritisation of urgent needs; and collaborative guidance, from the nurse, regarding accessing supports. RESULTS: Sixty-four FCs completed the FECH programme. The top three support needs identified by the FCs were: knowing what to expect in the future (52%), knowing who to contact if they were concerned (52%) and practical help in the home (36%). The telephone-based outreach service worked well and was convenient for the nurse and the FCs, and saved on transport, time and money. Most of the FCs appreciated the systematic approach to identify and articulate their needs and were satisfied with the support they received, mainly navigation through the systems, problem solving, self-care strategies, explanation of illness, symptoms and medication and access to after-hours services. CONCLUSIONS: In order to guide services which may consider adopting this systematic approach to supporting FCs and integrating it into their routine practice, this evaluation of the FECH programme has described the processes implemented and highlighted the factors that hindered or facilitated these processes to engage caregivers with appropriate services in a timely manner. Positive feedback indicated that the programme was a useful addition to hospital discharge planning. TRIAL REGISTRATION NUMBER: ACTRN12614001174673; Results

Field anaesthesia of the African elephant (Loxodonta africana)

Immobilisation and anaesthesia of elephants may be required for various reasons, such as the capture, transport and clinical examination of captive animals, e.g. at a zoological park, or for minor surgical procedures. General anaesthesia is required for wound treatment, i.e trunk lacerations and dental surgery, or population control, i.e. laparoscopic vasectomy.http://www.sajaa.co.za/index.php/sajaaam2014mn201