Letter to the Editor: Clotting Profiles and Coagulation Factors

We aimed to test the hypothesis that if a coagulation profile specimen clots then the patient's clotting profile must be normal

A Novel Mounting Device For Attaching Intracranial Probes To The Skull For Use In Experimental Research Models

A simple mount capable of securely holding a variety of intracranial probes to the skull was constructed from commonly available clinical consumables. Using this device the cerebral cortical blood flow of preterm lambs was measured using a laser Doppler flow probe, and cerebral pH and cortical electrical impedance were measured in newborn piglets using pH electrodes and Ag/AgCl wire electrodes. In both studies, the mount held the various probes for periods up to 6 h with no dislodgement or probe failure. The simple mount presented here can be adapted to a wide variety of intracranial probes and will hold them securely to the skull

Measurement of the transverse cerebellar diameter in preterm neonates and its use in assessment of gestational age

This study aims to confirm the relationship between gestational age (GA) and transverse cerebellar diameter (TCD), to define the prediction of GA by TCD, and assess the reliability of TCD measurements. Infants were included in the study if they had a routine cranial ultrasound scan by day 3, and the TCD was measured. Infants were excluded from the study if the GA was not known, if there was any cranio-spinal malformation or grade 3 or 4 intraventricular haemorrhage (IVH). The GA assessment was an early pregnancy scan or certain dates. Cranial ultrasound scans were done with a LOGIQ 500 scanner (GE Medical Systems, Waukesha, WI, USA) with a 7 MHz curvilinear sector probe (GE LOGIQ-C721; GE Medical Systems). The posterior fossa was scanned using the asterion as the acoustic window with the TCD measured in the coronal plane. Intra- and interobserver reliability were assessed. A total of 221 infants of known GA had their TCD measured. The linear regression for GA versus TCD is: GA weeks = (0.470 x TCD millimetres) + 13.162 (r = 0.89, r2 = 0.79, P < 0.001). The 95% confidence interval predicts GA to plus or minus 2.33 weeks for a given TCD. Intra- and interobserver intraclass correlation coefficients are 0.98 and 0.99, respectively. Transverse cerebellar diameter correlates closely with GA and predicts GA to plus or minus 2.33 weeks. Measurements of TCD have excellent reproducibility

Theory of valley-orbit coupling in a Si/SiGe quantum dot

Electron states are studied for quantum dots in a strained Si quantum well, taking into account both valley and orbital physics. Realistic geometries are considered, including circular and elliptical dot shapes, parallel and perpendicular magnetic fields, and (most importantly for valley coupling) the small local tilt of the quantum well interface away from the crystallographic axes. In absence of a tilt, valley splitting occurs only between pairs of states with the same orbital quantum numbers. However, tilting is ubiquitous in conventional silicon heterostructures, leading to valley-orbit coupling. In this context, "valley splitting" is no longer a well defined concept, and the quantity of merit for qubit applications becomes the ground state gap. For typical dots used as qubits, a rich energy spectrum emerges, as a function of magnetic field, tilt angle, and orbital quantum number. Numerical and analytical solutions are obtained for the ground state gap and for the mixing fraction between the ground and excited states. This mixing can lead to valley scattering, decoherence, and leakage for Si spin qubits.Comment: 18 pages, including 4 figure

Effective mass theory of monolayer \delta-doping in the high-density limit

Monolayer \delta-doped structures in silicon have attracted renewed interest with their recent incorporation into atomic-scale device fabrication strategies as source and drain electrodes and in-plane gates. Modeling the physics of \delta-doping at this scale proves challenging, however, due to the large computational overhead associated with ab initio and atomistic methods. Here, we develop an analytical theory based on an effective mass approximation. We specifically consider the Si:P materials system, and the limit of high donor density, which has been the subject of recent experiments. In this case, metallic behavior including screening tends to smooth out the local disorder potential associated with random dopant placement. While smooth potentials may be difficult to incorporate into microscopic, single-electron analyses, the problem is easily treated in the effective mass theory by means of a jellium approximation for the ionic charge. We then go beyond the analytic model, incorporating exchange and correlation effects within a simple numerical model. We argue that such an approach is appropriate for describing realistic, high-density, highly disordered devices, providing results comparable to density functional theory, but with greater intuitive appeal, and lower computational effort. We investigate valley coupling in these structures, finding that valley splitting in the low-lying \Gamma band grows much more quickly than the \Gamma-\Delta band splitting at high densities. We also find that many-body exchange and correlation corrections affect the valley splitting more strongly than they affect the band splitting

Antiviral immunity and T-regulatory cell function are retained after selective alloreactive T-cell depletion in both the HLA-identical and HLA-mismatched settings

AbstractNonselective T-cell depletion reduces the incidence of severe graft-versus-host disease after allogeneic hematopoietic stem cell transplantation, but the cost is delayed and disordered antigen-specific immune reconstitution and increased infection. We use a method of selective depletion of alloreactive T cells expressing the activation marker CD69 after coculture with stimulator cells in a modified or standard mixed lymphocyte reaction. The technique has been shown to reduce alloreactivity while retaining third-party responses in vitro and, in a mismatched murine model, led to donor T-cell engraftment with a virtual absence of graft-versus-host disease and increased survival. We show in a human HLA-mismatched and unrelated HLA-identical setting that this technique retains >80% of specific cellular antiviral activity by cytomegalovirus-tetramer analysis and cytomegalovirus/Epstein-Barr virus peptide-stimulated interferon-γ ELISpot assay. Furthermore, CD4+ CD25+ T-regulatory cells are not removed by this method of selective allodepletion and retain their function in suppressing allogeneic proliferative responses. Preservation of antiviral cytotoxic T lymphocytes in selectively allodepleted stem cell grafts would lead to improved antiviral immunity after transplantation. The retention of immunosuppressive CD4+ CD25+ T-regulatory cells could lead to more ordered immune reconstitution and further suppress alloreactive responses after transplantation

The use of chilled condensers for the recovery of perfluorocarbon liquid in an experimental model of perfluorocarbon vapour loss during neonatal partial liquid ventilation

Background: Perfluorocarbon (PFC) vapour in the expired gases during partial liquid ventilation should be prevented from entering the atmosphere and recovered for potential reuse. This study aimed to determine how much PFC liquid could be recovered using a conventional humidified neonatal ventilator with chilled condensers in place of the usual expiratory ventilator circuit and whether PFC liquid could be recovered when using the chilled condensers at the ventilator exhaust outlet. Methods: Using a model lung, perfluorocarbon vapour loss during humidified partial liquid ventilation of a 3.5 kg infant was approximated. For each test 30 mL of FC-77 was infused into the model lung. Condensers were placed in the expiratory limb of the ventilator circuit and the amounts of PFC (FC-77) and water recovered were measured five times. This was repeated with the condensers placed at the ventilator exhaust outlet. Results: When the condensers were used as the expiratory limb, the mean (± SD) volume of FC77 recovered was 16.4 mL (± 0.18 mL). When the condensers were connected to the ventilator exhaust outlet the mean (± SD) volume of FC-77 recovered was 7.6 mL (± 1.14 mL). The volume of FC-77 recovered was significantly higher when the condenser was used as an expiratory limb. Conclusion: Using two series connected condensers in the ventilator expiratory line 55% of PFC liquid (FC-77) can be recovered during partial liquid ventilation without altering the function of the ventilator circuit. This volume of PFC recovered was just over twice that recovered with the condensers connected to the ventilator exhaust outlet

Gastroschisis: Ward Reduction Compared With Traditional Reduction Under General Anesthesia

Background/Purpose In gastroschisis it is proposed that gut reduction may be achieved without intubation or general anesthesia (GA) through ward reduction. The authors aimed to determine if ward reduction decreased morbidity and duration of treatment. Methods Infants born from January 1, 1995, to December 31, 2001, with gastroschisis were managed with either reduction under GA in the operating theatre (OT group) - up to September 1999, or ward reduction (when eligible) in the neonatal unit without GA/ventilation (ward reduction [WR] group) - from September 1999. Results Of the 37 infants, 31 were eligible for ward reduction—15 from the OT group, 16 from the WR group. All infants in the OT group had at least 1 episode of ventilation and 1 GA: 62% of infants in the WR group avoided ventilation (P = .0002) and 81% avoided GA (P < .0001). Infants who had ward reduction had significantly shorter durations of ventilation and oxygen therapy. Septicemia occurred in 31% of the WR group and 7% of the OT group (P = .17). Infants who had ward reduction left intensive care 16 days earlier (P = .02) and tended to reach full enteral feeds 8 days sooner (P = .06) and be discharged from hospital 15 days earlier (P = .05). Conclusions Infants who had ward reduction do better in terms of avoiding GA/ventilation, establishing feeds, and going home earlier. A randomized, controlled trial comparing the 2 approaches is feasible, safe, and worthwhile