Caudate lobe resections: a single-center experience and evaluation of factors predictive of outcomes

BACKGROUND: Despite the increasing frequency of liver resection for multiple types of disease, caudate lobe resection remains a rare surgical event. The goal of this study is to review our experience and evaluate possible predictors of adverse outcomes in patients undergoing caudate lobectomy. METHODS: We reviewed a 1,900-patient prospective hepato-pancreatico-biliary database from January 2000 to December 2011, identifying 36 hepatectomy patients undergoing caudate lobe resection. Clinicopathologic characteristic and outcome data were compared using chi-square, T-test, ANOVA, Kaplan-Meier, and Cox regression analysis. Primary endpoints were the incidence and severity of complications, and secondary endpoints were blood loss, hospital stay, and transfusion requirements. Patients were also divided in two groups with group A being patients operated on before December 2007 and group B after 2007. We compared the demographics, risk factors, complication rates, and operative details between the two groups. RESULTS: Thirty-six patients underwent caudate lobe resection for cholangiocarcinoma (47.2%), metastatic colorectal cancer (36.1%), hepatocellular carcinoma (8.3%), or benign disease (8.3%). Nine patients (29%) had additional liver resection. Median overall survival (OS) was 21 months. Complications occurred in 52.7% (19/36) of patients with a median grade of 2. Tobacco abuse was associated with an increased risk of operative complications (73.3% vs. 38.9%, p = 0.03). Prior history of cardiac disease was associated with a higher complication rate (87% vs. 42%, p = 0.03). Neoadjuvant chemotherapy, biliary procedures, hepatitis, and prior major abdominal surgery were not predictive of complications. Major complication was also predicted by the volume of RBC transfusion (2.7 vs. 4.1 units, p = 0.003). In our subgroup analysis of the patients undergoing surgery before and after 2007, the two groups were well matched based on age, comorbidities, and risk factors. The complication rates and rates of high-grade complications were similar, but blood loss (600 ml vs. 400 ml, p = 0.03), inflow occlusion time (Pringle time 12.6 vs. 6, p = 0.00), and hospital stay (9.5 vs. 7 days, p = 0.01) were significantly lower in group B. CONCLUSIONS: With appropriate patient selection, caudate lobe resection is an effective component of surgery for hepatic disease. Tobacco use and prior cardiac history increase the risk of complications

Impact of proctoring on success rates for percutaneous revascularisation of coronary chronic total occlusions.

OBJECTIVE: To assess the impact of proctoring for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in six UK centres. METHODS: We retrospectively analysed 587 CTO procedures from six UK centres and compared success rates of operators who had received proctorship with success rates of the same operators before proctorship (pre-proctored) and operators in the same institutions who had not been proctored (non-proctored). There were 232 patients in the pre-proctored/non-proctored group and 355 patients in the post-proctored group. Complexity was assessed by calculating the Japanese CTO (JCTO) score for each case. RESULTS: CTO PCI success was greater in the post-proctored compared with the pre-proctored/non-proctored group (77.5% vs 62.1%, p<0.0001). In more complex cases where JCTO≥2, the difference in success was greater (70.7% vs 49.5%, p=0.0003). After proctoring, there was an increase in CTO PCI activity in centres from 2.5% to 3.5%, p<0.0001 (as a proportion of total PCI), and the proportion of very difficult cases with JCTO score ≥3 increased from 15.3% (35/229) to 29.7% (105/354), p<0.0001. CONCLUSIONS: Proctoring resulted in an increase in procedural success for CTO PCI, an increase in complex CTO PCI and an increase in total CTO PCI activity. Proctoring may be a valuable way to improve access to CTO PCI and the likelihood of procedural success

Assisted extraction of the energy level spacings and lever arms in direct current bias measurements of one-dimensional quantum wires, using an image recognition routine

A multiplexer technique is used to individually measure an array of 256 split gates on a single GaAs/AlGaAs heterostructure. This results in the generation of large volumes of data, which requires the development of automated data analysis routines. An algorithm is developed to find the spacing between discrete energy levels, which form due to transverse confinement from the split gate. The lever arm, which relates split gate voltage to energy, is also found from the measured data. This reduces the time spent on the analysis. Comparison with estimates obtained visually show that the algorithm returns reliable results for subband spacing of split gates measured at 1:4 K. The routine is also used to assess DC bias spectroscopy measurements at lower temperatures (50 mK). This technique is versatile and can be extended to other types of measurements. For example, it is used to extract the magnetic field at which Zeeman-split 1D subbands cross one another.This work was supported by the Engineering and Physical Sciences Research Council grant No. EP/IO14268/1.This is the accepted manuscript. The final version is available from AIP at http://scitation.aip.org/content/aip/journal/jap/117/1/10.1063/1.4905484

Creativity and the computer nerd: an exploration of attitudes

This study arises from our concern that many of our best art and design students are failing to make the most of the opportunities provided by IT because of their fear or dislike of computers. This not only deprives them of useful skills, but, even more importantly, deprives many IT based developments of their input. In this paper we investigate the relationship between attitudes to creativity and to computers among students. We quickly discard an approach based on theories of personality types as philosophically and educationally problematic. An approach based on the self-concept of artists and designers, in relation to their own creativity and to their feelings about computers, offers more hope of progress. This means that we do not try to define the attributes of "creative people". Rather, we ask what creativity means to students of art and design and relate these responses to their attitudes to computers. Self-concept depends on how the subjects see themselves within society and culture, and is liable to change as culture changes. One major instrument of cultural change at the present time is the growth of IT itself. We then describe a first attempt at using a psychological method - Kelly's Repertory Grids - to investigate the self-concept of artists and designers. It is hoped to continue with this approach in further studies over the next few years

Multiplexed charge-locking device for large arrays of quantum devices

We present a method of forming and controlling large arrays of gate-defined quantum devices. The method uses an on-chip, multiplexed charge-locking system and helps to overcome the restraints imposed by the number of wires available in cryostat measurement systems. The device architecture that we describe here utilises a multiplexer-type scheme to lock charge onto gate electrodes. The design allows access to and control of gates whose total number exceeds that of the available electrical contacts and enables the formation, modulation and measurement of large arrays of quantum devices. We fabricate such devices on n-type GaAs/AlGaAs substrates and investigate the stability of the charge locked on to the gates. Proof-of-concept is shown by measurement of the Coulomb blockade peaks of a single quantum dot formed by a floating gate in the device. The floating gate is seen to drift by approximately one Coulomb oscillation per hour.This work was supported by the Engineering and Physical Sciences Research Council Grant No. EP/K004077/1.This is the author accepted manuscript. The final version is available from AIP via http://dx.doi.org/10.1063/1.493201

Statistical study of conductance properties in one-dimensional quantum wires focusing on the 0.7 anomaly

The properties of conductance in one-dimensional (1D) quantum wires are statistically investigated using an array of 256 lithographically-identical split gates, fabricated on a GaAs/AlGaAs heterostructure. All the split gates are measured during a single cooldown under the same conditions. Electron many-body effects give rise to an anomalous feature in the conductance of a one-dimensional quantum wire, known as the `0.7 structure' (or `0.7 anomaly'). To handle the large data set, a method of automatically estimating the conductance value of the 0.7 structure is developed. Large differences are observed in the strength and value of the 0.7 structure [from $0.63$ to $0.84\times (2e^2/h)$], despite the constant temperature and identical device design. Variations in the 1D potential profile are quantified by estimating the curvature of the barrier in the direction of electron transport, following a saddle-point model. The 0.7 structure appears to be highly sensitive to the specific confining potential within individual devices.This is the author's accepted manuscript. The final version is published by ACS in Physical Review B and can be found here: http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.045426

Dependence of the 0.7 anomaly on the curvature of the potential barrier in quantum wires

. Ninety-eight one-dimensional channels defined using split gates fabricated on a GaAs/AlGaAs heterostructure are measured during one cooldown at 1.4 K. The devices are arranged in an array on a single chip and are individually addressed using a multiplexing technique. The anomalous conductance feature known as the "0.7 structure" is studied using statistical techniques. The ensemble of data shows that the 0.7 anomaly becomes more pronounced and occurs at lower values as the curvature of the potential barrier in the transport direction decreases. This corresponds to an increase in the effective length of the device. The 0.7 anomaly is not strongly influenced by other properties of the conductance related to density. The curvature of the potential barrier appears to be the primary factor governing the shape of the 0.7 structure at a given T and B.his work was supported by Engineering and Physical Sciences Research Council Grant No. EP/I014268/1

Effect of Split Gate Size on the Electrostatic Potential and 0.7 Anomaly within Quantum Wires on a Modulation-Doped GaAs/AlGaAs Heterostructure

© 2016 American Physical Society. © 2016 American Physical Society.We study 95 split gates of different size on a single chip using a multiplexing technique. Each split gate defines a one-dimensional channel on a modulation-doped GaAs/AlGaAs heterostructure, through which the conductance is quantized. The yield of devices showing good quantization decreases rapidly as the length of the split gates increases. However, for the subset of devices showing good quantization, there is no correlation between the electrostatic length of the one-dimensional channel (estimated using a saddle-point model) and the gate length. The variation in electrostatic length and the one-dimensional subband spacing for devices of the same gate length exceeds the variation in the average values between devices of different lengths. There is a clear correlation between the curvature of the potential barrier in the transport direction and the strength of the "0.7 anomaly": the conductance value of the 0.7 anomaly reduces as the barrier curvature becomes shallower. These results highlight the key role of the electrostatic environment in one-dimensional systems. Even in devices with clean conductance plateaus, random fluctuations in the background potential are crucial in determining the potential landscape in the active device area such that nominally identical gate structures have different characteristics