Raman Spectroscopy Using a Monolithic Spatial Heterodyne Raman Spectrometer for Planetary Exploration

Raman spectroscopy is a vibrational technique that provides detailed molecular and structural information for organic and inorganic molecules and minerals, and is uniquely suited for spacecraft applications, in the search for chemical indicators of life. This is why NASA sent two Raman spectrometers to Mars on the Mars 2020 Perseverance rover, as part of the SuperCam and SHERLOC instruments. The Raman spectrometers on Perseverance are conventional dispersive instruments that have been engineered to survive the harsh conditions of spaceflight. Future missions could benefit from smaller, more robust designs, especially missions to the Jovian planets, Jupiter and Saturn, their moons, asteroids and comets. The spatial heterodyne Raman spectrometer (SHRS) is one such spectrometer that has the potential to fit these needs. The SHRS is a Fourier transform interferometer with no moving parts that is capable of high spectral resolution, large spectral range, and very high light throughput as compared to dispersive slit-based spectrometers. And its design is compatible with monolithic construction techniques. This work describes a monolithic spatial heterodyne Raman spectrometer (mSHRS), where the optical components of the spectrometer are bonded to make a small, stable, one-piece structure. The mSHRS is very compact, measuring about 3.5 x 2.5 x 2.5 cm in size and weighing about 80 g. When compared to previously described free standing SHRS, the mSHRS was found to be more stable, have higher SNR, a large spectral range, and higher spectral resolution, and provided high SNR using CMOS camera detectors. The small size and high light throughput of the mSHRS makes it suitable for use with small platforms such as commercial drones, using the drone’s CMOS cameras as the detector. In drone studies, we found the performance of the mSHRS to be comparable to lab bench top measurements and the wide field of view of the mSHRS allowed measurements without the use of any collection optics, other than the drone camera lens. For some drone tests, an optical fiber was used to deliver the laser light to the sample, also possible because of the large field of view of the mSHRS

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P < 0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P = 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P = 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

Neutrino oscillation parameters from [nu]e appearance in the T2K experiment

The T2K Experiment is a long-baseline accelerator neutrino oscillation experiment, whose primary aim is to look for νe appearance in a νμ beam. A predominantly νμ beam is produced at J-PARC in Tokai on the east coast of Japan, and neutrino interactions are measured both by a near detector complex, 280 m from the neutrino production target,and by a large water Cerenkov detector, Super-Kamiokande, 295 km away. This thesis is concerned with oscillations νμ → νe, within both a standard three neutrino model and a model in which there is one additional sterile neutrino. By looking at νe appearance over the T2K baseline, this thesis looks for oscil- lations involving one additional sterile neutrino. A region of the short baseline neutrino oscillation parameter space favoured by other experiments is excluded at 3σ. The ND280 is also used to search for νe appearance over a short baseline. A νe selection is developed, and limits on the short baseline oscillation parameter space are set. Sensitivity predictions are also made for future T2K running. The T2K ND280 is interesting for this work since the detector technology is different to that of other experiments that have seen indications of short baseline electron-neutrino appearance. In the standard three-flavour neutrino oscillation picture, a combined analy- sis of the electron-neutrino appearance results of T2K and another long-baseline accelerator neutrino experiment, MINOS, is presented. Combining the two re- sults with the Feldman-Cousins method results in sin2 2θ13 = 0 being excluded at 2.7σ, assuming the normal neutrino mass hierarchy.</p

Neutrino oscillation parameters from [nu]e appearance in the T2K experiment

The T2K Experiment is a long-baseline accelerator neutrino oscillation experiment, whose primary aim is to look for νe appearance in a νμ beam. A predominantly νμ beam is produced at J-PARC in Tokai on the east coast of Japan, and neutrino interactions are measured both by a near detector complex, 280 m from the neutrino production target,and by a large water Cerenkov detector, Super-Kamiokande, 295 km away. This thesis is concerned with oscillations νμ → νe, within both a standard three neutrino model and a model in which there is one additional sterile neutrino. By looking at νe appearance over the T2K baseline, this thesis looks for oscil- lations involving one additional sterile neutrino. A region of the short baseline neutrino oscillation parameter space favoured by other experiments is excluded at 3σ. The ND280 is also used to search for νe appearance over a short baseline. A νe selection is developed, and limits on the short baseline oscillation parameter space are set. Sensitivity predictions are also made for future T2K running. The T2K ND280 is interesting for this work since the detector technology is different to that of other experiments that have seen indications of short baseline electron-neutrino appearance. In the standard three-flavour neutrino oscillation picture, a combined analy- sis of the electron-neutrino appearance results of T2K and another long-baseline accelerator neutrino experiment, MINOS, is presented. Combining the two re- sults with the Feldman-Cousins method results in sin2 2θ13 = 0 being excluded at 2.7σ, assuming the normal neutrino mass hierarchy.This thesis is not currently available in ORA

A graph theoretic analysis of leverage centrality

In 2010, Joyce et al. defined the leverage centrality of vertices in a graph as a means to analyze functional connections within the human brain. In this metric a degree of a vertex is compared to the degrees of all it neighbors. We investigate this property from a mathematical perspective. We first outline some of the basic properties and then compute leverage centralities of vertices in different families of graphs. In particular, we show there is a surprising connection between the number of distinct leverage centralities in the Cartesian product of paths and the triangle numbers