Diffusion thermopower of (Ga,Mn)As/GaAs tunnel junctions.

We report the observation of tunneling anisotropic magnetothermopower, a voltage response to a temperature difference across an interface between a normal and a magnetic semiconductor. The resulting voltage is related to the energy derivative of the density of states in the magnetic material, and thus has a strongly anisotropic response to the direction of magnetization in the material. The effect will have relevance to the operation of semiconductor spintronic devices, and may indeed already play a role in correctly interpreting the details of some earlier spin injection studies.

Tunable High Spatio-Spectral Purity Undulator Radiation from a Transported Laser Plasma Accelerated Electron Beam.

Undulator based synchrotron light sources and Free Electron Lasers (FELs) are valuable modern probes of matter with high temporal and spatial resolution. Laser Plasma Accelerators (LPAs), delivering GeV electron beams in few centimeters, are good candidates for future compact light sources. However the barriers set by the large energy spread, divergence and shot-to-shot fluctuations require a specific transport line, to shape the electron beam phase space for achieving ultrashort undulator synchrotron radiation suitable for users and even for achieving FEL amplification. Proof-of-principle LPA based undulator emission, with strong electron focusing or transport, does not yet exhibit the full specific radiation properties. We report on the generation of undulator radiation with an LPA beam based manipulation in a dedicated transport line with versatile properties. After evidencing the specific spatio-spectral signature, we tune the resonant wavelength within 200-300 nm by modification of the electron beam energy and the undulator field. We achieve a wavelength stability of 2.6%. We demonstrate that we can control the spatio-spectral purity and spectral brightness by reducing the energy range inside the chicane. We have also observed the second harmonic emission of the undulator.

Control of laser plasma accelerated electrons for light sources.

With gigaelectron-volts per centimetre energy gains and femtosecond electron beams, laser wakefield acceleration (LWFA) is a promising candidate for applications, such as ultrafast electron diffraction, multistaged colliders and radiation sources (betatron, compton, undulator, free electron laser). However, for some of these applications, the beam performance, for example, energy spread, divergence and shot-to-shot fluctuations, need a drastic improvement. Here, we show that, using a dedicated transport line, we can mitigate these initial weaknesses. We demonstrate that we can manipulate the beam longitudinal and transverse phase-space of the presently available LWFA beams. Indeed, we separately correct orbit mis-steerings and minimise dispersion thanks to specially designed variable strength quadrupoles, and select the useful energy range passing through a slit in a magnetic chicane. Therefore, this matched electron beam leads to the successful observation of undulator synchrotron radiation after an 8 m transport path. These results pave the way to applications demanding in terms of beam quality.

Publisher Correction: Control of laser plasma accelerated electrons for light sources.

The original version of this Article contained an error in the last sentence of the first paragraph of the Introduction and incorrectly read 'A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime in equation 11, nx(n-ß) x ß: n the two times and beta the two times should be bold since they are vectorsin Eq. 12, ß should be bold as well.' The correct version is 'A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime.'This has been corrected in both the PDF and HTML versions of the Article.

Two cases of intoxication with new synthetic opioid, U-47700.

BACKGROUND: Novel substances often referred to as "designer drugs" have emerged as drugs of abuse, and recognition of these is difficult as routine blood and urine screening tests do not detect these agents. U-47700 is a synthetic selective µ-opioid agonist that can be bought online for as little as $40 per gram. We report two patients presenting after insufflation of U-47700, with subsequent confirmation of this substance in urine samples. CASE DETAILS: A 26-year-old man and 24-year-old woman insufflated a substance they believed to be "synthetic cocaine." The man was found down with cyanosis and agonal respirations. He was intubated and taken to hospital where he recovered well with supportive care. The woman presented with anxiety, tremors and drowsiness and was admitted for observation. Urine samples from both patients were analyzed using GC/MS/MS and LC/QToF, and U-47700 was isolated in both cases. No other opioids were detected. DISCUSSION: These cases are concerning because U-47700 is a relatively new agent that is easy to obtain over the internet and has the potential to cause significant morbidity and mortality.

The role of latency in mandibular osteodistraction.

Even though osteodistraction has been well established in the extremities, the parameters used in craniofacial distraction have been essentially borrowed from orthopaedic experience. Latency is widely practised but its relevance has not been fully investigated. The purpose of this study was to establish the role of latency in mandibular distraction osteogenesis. Twenty-two growing Wethers sheep were allocated to four experimental groups. Six animals were allocated to each of Groups A, B and C and underwent bilateral mandibular corticotomies and attachment of an external lengthening device. Latent periods of 0, 4 and 7 days respectively were observed prior to beginning distraction. The distraction protocol consisted of a rate of 0.5 mm twice daily for 20 days, followed by a consolidation phase of 20 days after which the sheep were killed. Histology, bone densitometry and 3-point mechanical testing were performed on the harvested mandibles. Group D formed the control group (n = 4). Histologically, the distracted bone exhibited bone formation primarily via intramembranous ossification with scattered islands of cartilage. The regenerated bone had mechanical properties significantly weaker than the undistracted control group (P < 0.05), but between the experimental groups no statistically significant differences were demonstrable either in mechanical strength or DEXA density. These data indicate that a change in latency does not alter the properties of the regenerated bone in mandibular distraction osteogenesis and indeed no latent interval may be necessary at all in craniofacial distraction. This has implications for the duration of device fixation in distraction procedures.

Failed stereotactic radiosurgery for acoustic neuroma.

A case of recurrent acoustic neuroma in a 58-year-old man is presented. The tumour was initially subtotally removed and then was irradiated using stereotactic radiosurgery. He represented with ataxia and new onset headache four years later and underwent further surgery for recurrence of his acoustic neuroma. The literature is reviewed and the authors' view point on the different modalities of treatment is discussed.

The use of mimetic musculature in facial reconstruction.

Skin malignancy of all types is prevalent in Australia and the incidence is rising. Reconstruction of post-surgical excision defects in the face can be facilitated by the use of myocutaneous flaps using facial mimetic musculature. The mimetic musculature can be partially sacrificed without the loss of discernible facial tone or expression. Examples of their use include the frontalis, orbicularis oculi, nasalis, procerus, levator labii superioris, mentalis, orbicularis oris, platysma and SMAS. Myocutaneous flaps in the face enjoy the same advantages of increased skin viability as they do elsewhere in the body. Their use in the face is superior to the cosmetic results obtained by skin grafting alone or distant skin flap giving better colour match, increased vascularity and appropriate bulk when subcutaneous tissues and muscles have also been sacrificed in the initial extirpation of the skin malignancy.

Distraction osteogenesis in craniofacial surgery: a review.

Distraction osteogenesis is a technique of new bone formation by the gradual separation of bony fragments. The method, although initially developed for limb lengthening, is now being applied in the treatment of craniofacial deformities. A number of principles have been established through careful scientific study to guide clinical practice, such as the ideal rate and rhythm of distraction, the need for periosteal preservation during bone division, a "latent period" of neutral fixation before, and a "consolidation period" after distraction. The technique is being applied in craniofacial surgery particularly for mandibular deformities and offers considerable advantages over previous methods such as osteotomy and inlay bone grafting. Donor site morbidity is avoided, the investing soft tissue envelope is concurrently expanded, and the magnitude of the procedure is less. However, the technique is still in its infancy and requires further modification and refinement before widespread acceptance as a treatment in mainstream craniofacial surgery. Problems with cutaneous scarring and socially undesirable external hardware, particularly in the pediatric population, have led to the emergence of intraoral miniature devices, with the ultimate goal of development of a multiplanar internal autodistractor. Furthermore, many principles well established in leg lengthening, such as the rate and rhythm of distraction, need to be reexamined and the parameters redefined with particular reference to the craniofacial skeleton. Distraction osteogenesis has an expanding role in craniofacial surgery.

Expression of growth factors in the mandibular distraction zone: a sheep study.

Interest in craniofacial osteodistraction has increased in recent years parallel with the growing attention given to the role of growth factors in tissue healing and regeneration. This study was embarked upon to investigate the expression of bFGF, TGF-beta and IGF-1 in the distraction zone of the mandible. Fourteen growing sheep were allocated to three experimental groups. Six animals were allocated to Groups A and B (n = 12) and underwent bilateral mandibular corticotomies with fixation of an external lengthening device. The distraction protocol consisted of a rate of 1.0 mm/day (twice daily) for 20 days followed by a consolidation phase of 20 days after which the sheep were sacrificed. Group C comprised of age matched sham operated animals (n = 2). Bone histochemistry for growth factors were performed in the harvested mandibles. A strong staining of bFGF was seen in the osteoblasts, osteocytes and osteoid matrix following 20 days of distraction and 20 days of consolidation compared to the control group. TGF-beta and IGF-1 demonstrated mild but clear staining in osteocyte and osteoblast cells and TGF-beta stained positively in the osteoid seam in the experimental groups. These finding suggest that bFGF, IGF-1 and TGF-beta may play different roles in the remodelling phase of distraction osteogenesis.

Recurrence rates of ischial sores in para- and tetraplegics treated with hamstring flaps: an 8-year study.

We have collected data on the second follow-up of 27 patients who underwent musculocutaneous flap closure of their ischial pressure sores. Thirty-seven ulcers were operated on between 1988 and 1993 using the V-Y advancement hamstring musculocutaneous island flap. At the initial follow-up (mean = 20 months) in 1993, despite 33% of patients having had recurrent ulcers and 14.8% having undergone re-advancements, only 14% of patients had non-healing ulcers. In 1997, follow-up period ranged from 18 to 90 months, with a mean of 62 months. Four patients were lost to follow-up resulting in 23 patients (n = 23) for the current study. Nine patients were tetraplegic and the remaining 14 were paraplegic. Four of the 23 patients had died at follow-up therefore making the number of living patients 19 (n = 19). The total number of ulcers operated on in the current study was 29 (U = 29). Overall, ulcer and patient recurrence rates were 41.4% and 47.8% respectively. Despite this, 89.5% of patients had intact flaps at the time of follow-up. We recommend the use of the hamstring V-Y musculocutaneous flap as a reliable and safe reconstructive modality in the management of ischial pressure sores and by identifying the group of patients susceptible to ulcer recurrence we have proposed a protocol for their long-term follow-up.