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"Perry, R. A"
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The spin Hall effect in a quantum gas
The spin Hall effect, whereby flowing particles experience orthogonally directed, spin-dependent Lorentz-like forces, is observed in a quantum-degenerate gas and used to produce a cold-atom spin transistor.
Cold-atom spin transistor
The spin Hall effect is a phenomenon in which, in the absence of a magnetic field, particles such as electrons experience a Lorentz-like force with a direction depending on each particle's spin. The paper demonstrates the spin Hall effect in a quantum-degenerate Bose gas, realizing an analogue of a semiconductor spin transistor. The results have potential applications for magnetic or inertial sensors, and suggest a way of engineering topological insulators with quantized spin Hall effects in ultracold quantum gases.
Electronic properties such as current flow are generally independent of the electron’s spin angular momentum, an internal degree of freedom possessed by quantum particles. The spin Hall effect, first proposed 40 years ago
1
, is an unusual class of phenomena in which flowing particles experience orthogonally directed, spin-dependent forces—analogous to the conventional Lorentz force that gives the Hall effect, but opposite in sign for two spin states. Spin Hall effects have been observed for electrons flowing in spin–orbit-coupled materials such as GaAs and InGaAs (refs
2
,
3
) and for laser light traversing dielectric junctions
4
. Here we observe the spin Hall effect in a quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz forces to realize a cold-atom spin transistor. By engineering a spatially inhomogeneous spin–orbit coupling field for our quantum gas, we explicitly introduce and measure the requisite spin-dependent Lorentz forces, finding them to be in excellent agreement with our calculations. This ‘atomtronic’ transistor behaves as a type of velocity-insensitive adiabatic spin selector, with potential application in devices such as magnetic
5
or inertial
6
sensors. In addition, such techniques for creating and measuring the spin Hall effect are clear prerequisites for engineering topological insulators
7
,
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and detecting their associated quantized spin Hall effects in quantum gases. As implemented, our system realizes a laser-actuated analogue to the archetypal semiconductor spintronic device, the Datta–Das spin transistor
9
,
10
.
Journal Article
Synthetic Partial Waves in Ultracold Atomic Collisions
Interactions between particles can be strongly altered by their environment. We demonstrate a technique for modifying interactions between ultracold atoms by dressing the bare atomic states with light, creating an effective interaction of vastly increased range that scatters states of finite relative angular momentum at collision energies where only s-wave scattering would normally be expected. We collided two optically dressed neutral atomic Bose-Einstein condensates with equal, and opposite, momenta and observed that the usual s-wave distribution of scattered atoms was altered by the appearance of d-and g-wave contributions. This technique is expected to enable quantum simulation of exotic systems, including those predicted to support Majorana fermions.
Journal Article
A conformal array of microfabricated optically-pumped first-order gradiometers for magnetoencephalography
An array of 21 first-order gradiometers based on zero-field optically-pumped magnetometers is demonstrated for use in magnetoencephalography. Sensors are oriented radially with respect to the head and housed in a helmet with moveable holders which conform to the shape of a scalp. Our axial gradiometers have a baseline of 2 cm and reject laser and vibrational noise as well as common-mode environmental magnetic noise. The median sensitivity of the array is 15.4 fT/Hz1/2, measured in a human-sized magnetic shield. All magnetometers are operated independently with negative feedback to maintain atoms at zero magnetic field. This yields higher signal linearity and operating range than open-loop operation and a measurement system that is less sensitive to systematic and ambient magnetic fields. All of the system electronics and lasers are compacted into one equipment rack which offers a favorable outlook for use in clinical settings.
Journal Article
Characterisation of Glucose-Dependent Insulinotropic Polypeptide Receptor Antagonists in Rodent Pancreatic Beta Cells and Mice
Hypersecretion and alterations in the biological activity of the incretin hormone, glucose-dependent insulinotropic polypeptide (GIP), have been postulated as contributing factors in the development of obesity-related diabetes. However, recent studies also point to weight-reducing effects of GIP receptor activation. Therefore, generating precise experimental tools, such as specific and effective GIP receptor (GIPR) antagonists, is of key significance to better understand GIP physiology. Thus, the primary aim of the current study was to uncover improved GIPR antagonists for use in rodent studies, using human and mouse GIP sequences with N- and C-terminal deletions. Initial in vitro studies revealed that the GIPR agonists, human (h) GIP(1-42), hGIP(1-30) and mouse (m) GIP(1-30), stimulated (P < 0.01 to P < 0.001) insulin secretion from rat BRIN-BD11 cells. Analysis of insulin secretory effects of the N- and C-terminally cleaved GIP peptides, including hGIP(3-30), mGIP(3-30), h(Pro3)GIP(3-30), hGIP(5-30), hGIP(3-42) and hGIP(5-42), revealed that these peptides did not modulate insulin secretion. More pertinently, only hGIP(3-30), mGIP(3-30) and h(Pro3)GIP(3-30) were able to significantly (P < 0.01 to P < 0.001) inhibit hGIP(1-42)-stimulated insulin secretion. The human-derived GIPR agonist sequences, hGIP(1-42) and hGIP(1-30), reduced (P < 0.05) glucose levels in mice following conjoint injection with glucose, but mGIP(1-30) was ineffective. None of the N- and C-terminally cleaved GIP peptides affected glucose homeostasis when injected alone with glucose. However, hGIP(5-30) and mGIP(3-30) significantly (P < 0.05 to P < 0.01) impaired the glucose-lowering action of hGIP(1-42). Further evaluation of these most effective sequences demonstrated that mGIP(3-30), but not hGIP(5-30), effectively prevented GIP-induced elevations of plasma insulin concentrations. These data highlight, for the first time, that mGIP(3-30) represents an effective molecule to inhibit GIPR activity in mice.
Journal Article
Cost effectiveness of drug eluting coronary artery stenting in a UK setting: cost–utility study
Objective: To assess the cost effectiveness of drug eluting stents (DES) compared with conventional stents for treatment of symptomatic coronary artery disease in the UK. Design: Cost–utility analysis of audit based patient subgroups by means of a simple economic model. Setting: Tertiary care. Participants: 12 month audit data for 2884 patients receiving percutaneous coronary intervention with stenting at the Cardiothoracic Centre Liverpool between January 2000 and December 2002. Main outcome measures: Risk of repeat revascularisation within 12 months of index procedure and reduction in risk from use of DES. Economic modelling was used to estimate the cost–utility ratio and threshold price premium. Results: Four factors were identified for patients undergoing elective surgery (n = 1951) and two for non-elective surgery (n = 933) to predict risk of repeat revascularisation within 12 months. Most patients fell within the subgroup with lowest risk (57% of the elective surgery group with 5.6% risk and 91% of the non-elective surgery group with 9.9% risk). Modelled cost–utility ratios were acceptable for only one group of high risk patients undergoing non-elective surgery (only one patient in audit data). Restricting the number of DES for each patient improved results marginally: 4% of stents could then be drug eluting on economic grounds. The threshold price premium justifying 90% substitution of conventional stents was estimated to be £112 (US$212, €162) (sirolimus stents) or £89 (US$167, €130) (paclitaxel stents). Conclusions: At current UK prices, DES are not cost effective compared with conventional stents except for a small minority of patients. Although the technology is clearly effective, general substitution is not justified unless the price premium falls substantially.
Journal Article
An echocardiographic assessment of cardiac morphology and common ECG findings in teenage professional soccer players: reference ranges for use in screening
OBJECTIVE To assess physiological cardiac adaptation in adolescent professional soccer players. SUBJECTS AND DESIGN Over a 32 month period 172 teenage soccer players were screened by echocardiography and ECG at a tertiary referral cardiothoracic centre. They were from six professional soccer teams in the north west of England, competing in the English Football League. One was excluded because of an atrial septal defect. The median age of the 171 players assessed was 16.7 years (5th to 95th centile range: 14–19) and median body surface area 1.68 m2 (1.39–2.06 m2). MAIN OUTCOME MEASURES Standard echocardiographic measurements were compared with predicted mean, lower, and upper limits in a cohort of normal controls after matching for age and surface area. Univariate regression analysis was used to assess the correlation between echocardiographic variables and the age and surface area of the soccer player cohort. ECG findings were also assessed. RESULTS All mean echocardiographic variables were greater than predicted for age and surface area matched controls (p < 0.001). All variables except left ventricular septal and posterior wall thickness showed a modest linear correlation with surface area (r = 0.2 to 0.4, p < 0.001); however, left ventricular mass was the only variable that was significantly correlated with age (r = 0.2, p < 0.01). Only six players (3.5%) had structural anomalies, none of which required further evaluation. All had normal left ventricular systolic function. Sinus bradycardia was found in 65 (39%). The Solokow–Lyon voltage criteria for left ventricular hypertrophy were present in 85 (50%) and the Romhilt–Estes points score (five or more) in 29 (17%). Repolarisation changes were present in 19 (11%), mainly in the inferior leads. CONCLUSIONS Chamber dimensions, left ventricular wall thickness and mass, and aortic root size were all greater than predicted for controls after matching for age and surface area. Sinus bradycardia and the ECG criteria for left ventricular hypertrophy were common but there was poor correlation with echocardiographic left ventricular hypertrophy. The type of hypertrophy found reflected the combined endurance and strength based training undertaken.
Journal Article
Dietary intake in Australian children aged 4–24 months: consumption of meat and meat alternatives
Meat/meat alternatives (M/MA) are key sources of Fe, Zn and protein, but intake tends to be low in young children. Australian recommendations state that Fe-rich foods, including M/MA, should be the first complementary foods offered to infants. The present paper reports M/MA consumption of Australian infants and toddlers, compares intake with guidelines, and suggests strategies to enhance adherence to those guidelines. Mother–infant dyads recruited as part of the NOURISH and South Australian Infants Dietary Intake studies provided 3 d of intake data at three time points: Time 1 (T1) (n 482, mean age 5·5 (sd 1·1) months), Time 2 (T2) (n 600, mean age 14·0 (sd 1·2) months) and Time 3 (T3) (n 533, mean age 24 (sd 0·7) months). Of 170 infants consuming solids and aged greater than 6 months at T1, 50 (29 %) consumed beef, lamb, veal (BLV) or pork on at least one of 3 d. Commercial infant foods containing BLV or poultry were the most common form of M/MA consumed at T1, whilst by T2 BLV mixed dishes (including pasta bolognaise) became more popular and remained so at T3. The processed M/MA increased in popularity over time, led by pork (including ham). The present study shows that M/MA are not being eaten by Australian infants or toddlers regularly enough; or in adequate quantities to meet recommendations; and that the form in which these foods are eaten can lead to smaller M/MA serve sizes and greater Na intake. Parents should be encouraged to offer M/MA in a recognisable form, as one of the first complementary foods, in order to increase acceptance at a later age.
Journal Article
A case of EBV-associated lymphoproliferative disease following high-dose therapy and CD34-purified autologous peripheral blood progenitor cell transplantation
A fatal case of EBV-associated lymphoproliferative disorder arising after a CD34-selected autologous peripheral blood stem cell transplant is reported in a patient with multiple myeloma in first plateau phase. It is suggested that this is likely to be a consequence of the accessory cell depletion associated with the CD34+ cell purification and it is recommended that a source of autologous T cells is stored before transplantation to be used if a severe opportunistic infection or EBV lymphoma arises post-transplantation.
Journal Article
Progenitor cell yields are frequently poor in patients with histologically indolent lymphomas especially when mobilized within 6 months of previous chemotherapy
High-dose therapy with peripheral blood stem cell (PBSC) support is a frequently used treatment option in younger patients with poor prognosis histologically indolent (low-grade) non-Hodgkin's lymphoma (NHL), usually at the time of second or subsequent response to conventional-dose therapy. We have undertaken PBSC collection in 57 patients with histologically indolent NHL mobilized with either cyclophosphamide 1.5 g/m2 or the ESHAP regimen, followed by daily G-CSF. Progenitor cell yields were determined by quantification of CD34+ cells and GM-CFC. Twelve patients (21%) failed to achieve the minimum progenitor cell requirements of 1 x 10(6)/kg CD34+ cells or 1 x 10(5)/kg GM-CFC in their pooled harvests and 40 patients (70%) failed to achieve the optimal harvest thresholds of 3.5 x 10(6)/kg CD34+ cells or 3.5 x 10(5)/kg GM-CFC. This high failure rate is significantly higher than that in patients with histologically aggressive NHL or Hodgkin's disease. A multivariate analysis was performed to identify factors contributing to the low stem cell yields in this group. This identified the time interval from the last chemotherapy to the priming chemotherapy as the most important predictive factor. With respect to CD34 and GM-CFC numbers, on the single harvest on the day the white cell count first exceeded 5 x 10(9)/l the P values were 0.0078 and 0.0065, respectively, and for the progenitor cell values on the pooled harvests the P values were 0.004 for CD34+ cells and 0.015 for GM-CFC. Progenitor cell yields may therefore be improved in patients with low grade lymphoma by harvesting at diagnosis if no marrow disease is present, or by delaying mobilization for 6 months post-chemotherapy in patients in first or subsequent remission.
Journal Article