Bolometer operating at the threshold for circuit quantum electrodynamics.

Radiation sensors based on the heating effect of absorbed radiation are typically simple to operate and flexible in terms of input frequency, so they are widely used in gas detection1, security2, terahertz imaging3, astrophysical observations4 and medical applications5. Several important applications are currently emerging from quantum technology and especially from electrical circuits that behave quantum mechanically, that is, circuit quantum electrodynamics6. This field has given rise to single-photon microwave detectors7-9 and a quantum computer that is superior to classical supercomputers for certain tasks10. Thermal sensors hold potential for enhancing such devices because they do not add quantum noise and they are smaller, simpler and consume about six orders of magnitude less power than the frequently used travelling-wave parametric amplifiers11. However, despite great progress in the speed12 and noise levels13 of thermal sensors, no bolometer has previously met the threshold for circuit quantum electrodynamics, which lies at a time constant of a few hundred nanoseconds and a simultaneous energy resolution of the order of 10h gigahertz (where h is the Planck constant). Here we experimentally demonstrate a bolometer that operates at this threshold, with a noise-equivalent power of 30 zeptowatts per square-root hertz, comparable to the lowest value reported so far13, at a thermal time constant two orders of magnitude shorter, at 500 nanoseconds. Both of these values are measured directly on the same device, giving an accurate estimation of 30h gigahertz for the calorimetric energy resolution. These improvements stem from the use of a graphene monolayer with extremely low specific heat14 as the active material. The minimum observed time constant of 200 nanoseconds is well below the dephasing times of roughly 100 microseconds reported for superconducting qubits15 and matches the timescales of currently used readout schemes16,17, thus enabling circuit quantum electrodynamics applications for bolometers.

Operation of a silicon quantum processor unit cell above one kelvin.

Quantum computers are expected to outperform conventional computers in several important applications, from molecular simulation to search algorithms, once they can be scaled up to large numbers-typically millions-of quantum bits (qubits)1-3. For most solid-state qubit technologies-for example, those using superconducting circuits or semiconductor spins-scaling poses a considerable challenge because every additional qubit increases the heat generated, whereas the cooling power of dilution refrigerators is severely limited at their operating temperature (less than 100 millikelvin)4-6. Here we demonstrate the operation of a scalable silicon quantum processor unit cell comprising two qubits confined to quantum dots at about 1.5 kelvin. We achieve this by isolating the quantum dots from the electron reservoir, and then initializing and reading the qubits solely via tunnelling of electrons between the two quantum dots7-9. We coherently control the qubits using electrically driven spin resonance10,11 in isotopically enriched silicon12 28Si, attaining single-qubit gate fidelities of 98.6 per cent and a coherence time of 2 microseconds during 'hot' operation, comparable to those of spin qubits in natural silicon at millikelvin temperatures13-16. Furthermore, we show that the unit cell can be operated at magnetic fields as low as 0.1 tesla, corresponding to a qubit control frequency of 3.5 gigahertz, where the qubit energy is well below the thermal energy. The unit cell constitutes the core building block of a full-scale silicon quantum computer and satisfies layout constraints required by error-correction architectures8,17. Our work indicates that a spin-based quantum computer could be operated at increased temperatures in a simple pumped 4He system (which provides cooling power orders of magnitude higher than that of dilution refrigerators), thus potentially enabling the integration of classical control electronics with the qubit array18,19.

Detection of Zeptojoule Microwave Pulses Using Electrothermal Feedback in Proximity-Induced Josephson Junctions.

We experimentally investigate and utilize electrothermal feedback in a microwave nanobolometer based on a normal-metal (Au_{x}Pd_{1-x}) nanowire with proximity-induced superconductivity. The feedback couples the temperature and the electrical degrees of freedom in the nanowire, which both absorbs the incoming microwave radiation, and transduces the temperature change into a radio-frequency electrical signal. We tune the feedback in situ and access both positive and negative feedback regimes with rich nonlinear dynamics. In particular, strong positive feedback leads to the emergence of two metastable electron temperature states in the millikelvin range. We use these states for efficient threshold detection of coherent 8.4 GHz microwave pulses containing approximately 200 photons on average, corresponding to 1.1×10^{-21} J≈7.0 meV of energy.

'Start to finish trans-institutional transdisciplinary care': a novel approach improves colorectal surgical results in frail elderly patients.

AIM: The frail elderly surgical patient is at increased risk of morbidity after major surgery. A transdisciplinary Geriatric Surgery Service (GSS) has been shown to produce consistently positive results in our institution. A trans-institutional transdisciplinary Start to Finish (STF) programme was initiated incorporating seamless prehabilitation and rehabilitation to enhance the outcome further. METHOD: Patients who underwent major colorectal resection in Khoo Teck Puat Hospital and were managed under the GSS from January 2007 to December 2014 were included in this prospective study. The STF programme was initiated from January 2012. The surgical outcome of patients managed under the GSS before the initiation of STF was compared with that after its implementation. RESULTS: There were 57 patients after the initiation of the STF programme compared with 60 patients managed before STF. There were 26.4% and 25% of frail patients in the STF group compared with the non-STF group (P = 0.874). The mean length of hospital stay was significantly shorter in the STF group (8.4 days vs 11.0 days, P = 0.029). Functional recovery in patients available for follow-up at 6 weeks showed 100% (46/46) recovery in the elective STF group who received prehabilitation and 95.7% (45/47) in the elective non-STF group who did not (P = 0.157). There were no significant differences in a Clavien-Dindo complication score of Grade 3 or more and 30-day mortality between the two groups. CONCLUSION: Through a trans-institutional transdisciplinary approach, we managed to achieve a significantly shorter hospital stay in frail patients having colorectal surgery. All elective patients who received prehabilitation achieved full functional recovery.

Randomized single-blind clinical trial of intradermal methylene blue on pain reduction after open diathermy haemorrhoidectomy.

BACKGROUND: Open haemorrhoidectomy has been associated with considerable postoperative pain and discomfort. Perianal intradermal injection of methylene blue has been shown to ablate perianal nerve endings and may bring about temporary pain relief after haemorrhoidectomy. We hypothesized that the administration of intradermal methylene blue would reduce postoperative pain during the initial period after surgery. METHOD: A randomized, prospective, single-blind placebo-controlled trial was conducted. Patients were randomized to intradermal injection at haemorrhoidectomy of either 4 ml 1% methylene blue and 16 ml 0.5% marcaine or of 16 ml 0.5% marcaine and 4 ml saline prior to surgical dissection. Patients were asked to fill in a pain diary with a visual analogue scale. The primary outcome measure was pain score and analgesic use. Secondary outcomes were complications. RESULTS: There were 37 patients in the methylene blue arm and 30 patients in the placebo arm. There were no statistically significant differences in the sex, type of haemorrhoid, number of haemorrhoids excised, duration of surgery or hospital stay. The mean pain scores were significantly lower and the use of paracetamol was also significantly less in the methylene blue group during the first three postoperative days. The risk ratio of acute urinary retention occurring when methylene blue was not used was 2.320 (95% CI 1.754-3.067). Other complication rates were not significantly different. CONCLUSION: Perianal intradermal injection of methylene blue was useful in reducing the initial postoperative pain of open haemorrhoidectomy.

Nanoscale broadband transmission lines for spin qubit control.

The intense interest in spin-based quantum information processing has caused an increasing overlap between the two traditionally distinct disciplines of magnetic resonance and nanotechnology. In this work we discuss rigorous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field used to drive a spin-based quantum bit (or qubit) while minimizing the disturbance to a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.

Reproducibility and diagnostic value of E100 event recorder for patients with complains on heart arrhythmias and no changes on multiple routine ECGs and 24-hour holter monitoring.

Aim of the study was to assess reproducibility and diagnostic value of E100 event recorder for patients with complains on heart arrhythmias and no abnormalities on multiple routine ECGs and/or 24-hour Holter ECG monitoring and the second one, an assessment of adherence and attitude of patients to the E100 event recorder, dependent on the results of self- assessment questionnaires. 24 patients with complains on heart arrhythmias were included in the study. All the patients were provided with the REKA E100 event monitors for 5 ± 2 days and self-assessment questionnaires to assess level of adherence and attitude of patients to the E100 event recorder. E100 event recorders revealed junctional rhythm (n=2), AV nodal reentrant tachycardia (n=2), extrasystolic arrhythmias (n=10), atrial fibrillation (n=2), WPW syndrome (n=4), ventricular tachycardia (n=1), sinus tachycardia (n=7) and complete AV block (n=1). Majority of patients consider device as easy to use, comfortable and safe. In comparison with multiple routine ECGs and 24-hour Holter ECG monitoring, E100 event recorders showed higher reproducibility and efficacy for detecting and interpreting heart arrhythmias.

A randomized phase II study comparing two schedules of the 21-day regimen of gemcitabine and carboplatin in advanced non-small cell lung cancer.

PURPOSE: Carboplatin area under the curve (AUC) 5 ml/min on day 1 with gemcitabine 1,250 mg/m(2) on day 1 and day 8 is a widely used regimen in advanced non-small cell lung cancer. Grade 3-4 thrombocytopenia and neutropenia are frequent. The aim of this study is to investigate whether toxicity of gemcitabine/carboplatin could be reduced by administering carboplatin on day 8 instead of day 1 without a decrease in response rate (RR). METHODS: Patients received gemcitabine 1,250 mg/m(2) on days 1 and 8, carboplatin AUC 5 on day 1 (arm A) or day 8 (arm B). Drugs were administered over a 21-day cycle. Toxicity and RR were evaluated weekly and every second cycle, respectively. RESULTS: 71 patients were enrolled into the study. We found 79% (95% CI 61-91%) grade 3-4 toxicity (neutropenia and thrombocytopenia) in arm A and 50% (95% CI 32-68%) in arm B; 66% grade 3-4 thrombocytopenia in arm A and 26% in arm B. We observed 30% grade 4 hematological toxicity in arm A and 3% in arm B. In arm A an overall RR of 20% (95% CI 7.7-38.6%) was seen, and 18.2% (95% CI 7-35.5%) in arm B. CONCLUSIONS: Although the study was prematurely closed, the current data are of interest. The schedule with carboplatin on day 8 is associated with substantially lower grade 3-4 neutropenia and thrombocytopenia with comparable dose intensity and RR.

Distribution of the first metastatic lymph node in colon cancer and its clinical significance.

INTRODUCTION: The pattern of distribution of lymph node metastasis in resected specimens of colon cancer has been rarely reported in the English literature. The aim of this study was to determine the location of the first metastatic lymph node, giving insight into the drainage pattern of colon cancer lymphatics. METHOD: All lymph nodes in the mesentery of the resected specimen were carefully harvested and their precise locations documented. Patients with a single metastatic node in the resected specimen were included in the study. RESULTS: Ninety-three patients with only one metastatic lymph node found on histology were studied. The mean number of lymph nodes per specimen was 22.3 (range: 8-72). The patients' first metastatic node was not directly below the tumour in 48% of cases. The first metastatic node was found in the region either along the feeding vessels (skipping the pericolic nodes) or in the pericolic area outside 5 cm on either side of the tumour edge in 18% of cases. No factors were found to be predictive for lymph node metastasis occurring elsewhere other than in the pericolic region just below the tumour. CONCLUSION: Although there has been recent resurgence of interest in using sentinel node biopsy to limit surgical dissection to facilitate minimally access and natural orifice surgery, the present study is a warning that this may compromise oncological clearance. Radical surgery should remain standard practice for colorectal cancer.

Accelerated learning curve for colorectal resection, open versus laparoscopic approach, can be attained with expert supervision.

BACKGROUND: Laparoscopic colorectal resection (LCR) is gaining popularity. Nonetheless, open surgery remains an important technique. Thus, surgeons should be technically proficient in both open and laparoscopic surgery. One question however remains unanswered: Can training for open and LCR occur simultaneously? The objective of this paper is to review the learning curve for open and laparoscopic colon resection of one surgeon who underwent a rigorous training program. METHODS: A review of consecutive patients who underwent surgery for colon and rectosigmoid junction cancers by one trainee surgeon was performed. This surgeon had completed his basic surgical residency but had limited experience in colorectal cancer surgery. In total, 75 patients were included in this study. All operations were supervised by at least one staff surgeon with experience of more than 300 LCR cases. The trainee surgeon was allowed to train in both laparoscopic and open colorectal resection simultaneously. RESULTS: Forty-three patients underwent laparoscopic resection, while 32 patients underwent open surgery. Age, gender, mean body mass index (BMI), preoperative risk, and history of past abdominal surgery showed no significant difference between laparoscopic and open groups. There were no differences in tumor stage [International Union against Cancer (UICC)] or tumor size (p = 0.068 and 0.228, respectively). The morbidity rate for open and laparoscopic surgery was 3.1% (1/32) and 4.7% (2/43), respectively (p = 0.484). Operation time decreased with increasing experience, and plateaued after 25 cases in the laparoscopic group and 22 cases in the open group. The learning curve for open cases was 11 cases, and 7 for laparoscopic surgery. CONCLUSIONS: Surgeons who have completed a basic surgical residency but have limited colorectal surgery experience can learn both open and laparoscopic colorectal surgery simultaneously in an effective manner under supervision by well-experienced surgeons.

Seroma prevention strategies in laparoscopic ventral hernia repair: a systematic review.

BACKGROUND: Laparoscopic ventral hernia repair (LVHR) has been increasing in popularity over the years. Seroma formation is a common complication of LVHR. The aim of this study is to review the current evidence on seroma prevention strategies following LVHR. METHODS: A systematic search of PubMed, Embase (1946-13 February 2019) and Medline (1946-13 February 2019) databases was conducted using terms which include "seroma", "hernia, ventral" and "laparoscopy". All studies are comparative retrospective or prospective human adult studies in peer-reviewed journals describing at least one intra-operative intervention designed to decrease the rate of seroma formation in laparoscopic ventral hernia repair. RESULTS: The database searches identified 3762 citations, and 21 studies were included for final analysis. Five studies compared the different methods of mesh fixation, nine studies compared primary defect closure (PFC) and bridged repair, two studies compared the effect of different types of meshes, two studies looked into the use of electrical cauterization, one study compared single- site laparoscopy with conventional laparoscopy, one study looked into the use of fibrin sealant and one study compared transabdominal preperitoneal placement of mesh with conventional repair. PFC appears to be the most promising with large studies showing a low rate of seroma formation with additional benefits of decreasing wound infection and recurrence rate. Cauterisation of hernia sac and injection of fibrin sealant also show promising results but are mainly derived from small studies. Other strategies did not demonstrate benefit. CONCLUSION: Currently, primary fascial closure appears to be the most promising strategy available to decrease seroma formation after LVHR based on the results of large studies. Other promising strategies that decrease dead space such as cauterisation of the sac and fibrin sealant injection will require further multicentre trials to confirm benefit before an increase in operative time and cost can be justified for their routine use.

Coherent spin control of s-, p-, d- and f-electrons in a silicon quantum dot.

Once the periodic properties of elements were unveiled, chemical behaviour could be understood in terms of the valence of atoms. Ideally, this rationale would extend to quantum dots, and quantum computation could be performed by merely controlling the outer-shell electrons of dot-based qubits. Imperfections in semiconductor materials disrupt this analogy, so real devices seldom display a systematic many-electron arrangement. We demonstrate here an electrostatically confined quantum dot that reveals a well defined shell structure. We observe four shells (31 electrons) with multiplicities given by spin and valley degrees of freedom. Various fillings containing a single valence electron-namely 1, 5, 13 and 25 electrons-are found to be potential qubits. An integrated micromagnet allows us to perform electrically-driven spin resonance (EDSR), leading to faster Rabi rotations and higher fidelity single qubit gates at higher shell states. We investigate the impact of orbital excitations on single qubits as a function of the dot deformation and exploit it for faster qubit control.

Multimedia article. Transanal endoscopic resection of the rectum with high ligation on a swine model--a novel type of natural orifice endoscopic surgery.

We present the video of a transanal radical resection of the rectum on a swine model (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A4). The equipment used included simple instruments used in perianal surgery and a flexible endoscope with diathermy. The equipment and skill set required for this technique is easily accessible and reproduced. The potential exists to further develop this procedure with the ultimate aim of performing an incisionless and painless radical resection of the rectum in humans.

Colorectal surgery in octogenarian patients--outcomes and predictors of morbidity.

INTRODUCTION: Surgery for elderly patients pose a constant challenge. This study aims to review the outcome and find predictors of adverse outcome in octogenarians undergoing major colorectal resection for cancer. METHODS: A review of 121 octogenarians who underwent colorectal cancer surgery between September 1992 and May 2008 was performed. Comorbidities were quantified using the weighted Charlson Comorbidity Index and ASA classification. CR-POSSUM scores and ACPGBI scores and the predicted mortality rates were calculated. Outcome measures were morbidity rates and 30-day mortality rates. RESULTS: The patients had a mean age of 83.5 years (range, 80-99). The mean index of comorbidity was 3.1 (2-7) and 12.5% of patients were classified ASA III and above. The mean predicted mortality rate based on CR-POSSUM and ACPGBI scoring models were 11.2% and 5.4% respectively. The overall observed morbidity rate was 30.7% and 30-day mortality was 1.6. Factors found on bivariate analysis to be significantly associated with an increased risk of morbidity were tumor presenting with complication, comorbid coronary heart disease, serum urea levels, ASA classification > or =3 and comorbidity index 3 of 5 > or = 5. Multivariate analysis revealed the latter two factors to be independent predictors of morbidity. CONCLUSION: Octogenarians undergoing major colorectal resection have an acceptable perioperative morbidity and mortality rate and survival rate and should not be denied surgery based on age alone. Comorbidity index scores and ASA scores are useful tools to identify poor risk patients.

The use of a wound protector to prevent port site recurrence may not be totally logical.

The wound protector has been used widely to prevent port site metastases (PSM). Although port site metastases ties in with poor survival, it is not because of PSM itself, but rather because PSM is a sign of more widespread metastatic disease. Whilst being touted as a method of preventing PSM, it fails to address the bigger issue of preventing intra-abdominal recurrence. Proper surgical technique in tumour handling following rigorous oncological principles, and not just putting in a wound protector is the key to good surgery with low recurrences and excellent survival rates.

Life-threatening perineal sepsis after rubber band ligation of haemorrhoids.

Rubber band ligation is a widely performed procedure in the outpatient setting for symptomatic haemorrhoids. This method is generally considered to be safe and easily performed. However, there have been reports of severe sepsis following interventions for haemorrhoids and the majority of patients had undergone rubber band ligation. We present a patient who had undergone elective rubber band ligation of haemorrhoids who presented with severe anal pain with difficulty in micturition. She deteriorated rapidly over a period of 3 days and succumbed to fulminant perineal sepsis.

Sushi-roll wrap of Seprafilm for ileostomy limbs facilitates ileostomy closure.

BACKGROUND: Sodium hyaluronate and carboxymethylcellulose membrane (Seprafilm) reduced postoperative intraabdominal adhesion. In this study, we examined whether Seprafilm reduces operative difficulties in ileostomy closure. PATIENTS AND METHODS: During the creation of the ileostomy, Seprafilm was cut in half and used to wrap both the ileum and mesentery. Patients who underwent ileostomy closure before February 2008 (without Seprafilm, Group T, n = 18) and after March (with Seprafilm, Group S, n = 18) were enrolled in this study. All operations were performed by surgical residents. Operative time and perioperative complications were analyzed. RESULTS: The mean operative time of Group S (106.88 min) was significantly less than that of Group T (120.6 min). The amount of intraoperative bleeding in Groups S and T was not significantly different and there were no major complications. CONCLUSION: Seprafilm applied to the two limbs of the ileostomy and mesentery facilitate ileostomy closure done by non-expert surgeons.

Single-spin qubits in isotopically enriched silicon at low magnetic field.

Single-electron spin qubits employ magnetic fields on the order of 1 Tesla or above to enable quantum state readout via spin-dependent-tunnelling. This requires demanding microwave engineering for coherent spin resonance control, which limits the prospects for large scale multi-qubit systems. Alternatively, singlet-triplet readout enables high-fidelity spin-state measurements in much lower magnetic fields, without the need for reservoirs. Here, we demonstrate low-field operation of metal-oxide-silicon quantum dot qubits by combining coherent single-spin control with high-fidelity, single-shot, Pauli-spin-blockade-based ST readout. We discover that the qubits decohere faster at low magnetic fields with [Formula: see text] µs and [Formula: see text] µs at 150 mT. Their coherence is limited by spin flips of residual 29Si nuclei in the isotopically enriched 28Si host material, which occur more frequently at lower fields. Our finding indicates that new trade-offs will be required to ensure the frequency stabilization of spin qubits, and highlights the importance of isotopic enrichment of device substrates for the realization of a scalable silicon-based quantum processor.

Flux-tunable heat sink for quantum electric circuits.

Superconducting microwave circuits show great potential for practical quantum technological applications such as quantum information processing. However, fast and on-demand initialization of the quantum degrees of freedom in these devices remains a challenge. Here, we experimentally implement a tunable heat sink that is potentially suitable for the initialization of superconducting qubits. Our device consists of two coupled resonators. The first resonator has a high quality factor and a fixed frequency whereas the second resonator is designed to have a low quality factor and a tunable resonance frequency. We engineer the low quality factor using an on-chip resistor and the frequency tunability using a superconducting quantum interference device. When the two resonators are in resonance, the photons in the high-quality resonator can be efficiently dissipated. We show that the corresponding loaded quality factor can be tuned from above 105 down to a few thousand at 10 GHz in good quantitative agreement with our theoretical model.