Robert Thomas

Stochastic Multiconfigurational Self-Consistent Field Theory.

The multiconfigurational self-consistent field theory is considered the standard starting point for almost all multireference approaches required for strongly correlated molecular problems. The limitation of the approach is generally given by the number of strongly correlated orbitals in the molecule, since its cost will grow exponentially with this number. We present a new multiconfigurational self-consistent field approach, wherein linear determinant coefficients of a multiconfigurational wave function are optimized via the stochastic full configuration interaction quantum Monte Carlo technique at greatly reduced computational cost, with nonlinear orbital rotation parameters updated variationally based on this sampled wave function. This extends this approach to strongly correlated systems with far larger active spaces than it is possible to treat via conventional means. By comparison with this traditional approach, we demonstrate that the introduction of stochastic noise in both the determinant amplitudes and the gradient and Hessian of the orbital rotations does not preclude robust and reliable convergence of the orbital optimization. It can even improve the ability to avoid convergence to local minima in the orbital space, and therefore aid in finding variationally lower-energy solutions. We consider the effect on the convergence of the orbitals as the number of walkers and the sampling time within the active space increases, as well as the effect on the final energy and error. The scope of the new protocol is demonstrated with a study of the increasingly strongly correlated electronic structure in a series of polycyclic aromatic hydrocarbons, up to the large coronene molecule in a complete active space of 24 π electrons in 24 orbitals, requiring only modest computational resources

Symmetry Breaking and Broken Ergodicity in Full Configuration Interaction Quantum Monte Carlo.

The initiator full configuration interaction quantum Monte Carlo method (i-FCIQMC) is applied to the binding curve of N2 in Slater-determinant Hilbert spaces formed of both canonical restricted Hartree-Fock (RHF) and symmetry-broken unrestricted Hartree-Fock (UHF) orbitals. By explicit calculation, we demonstrate that the technique yields the same total energy for both types of orbital but that as the bond is stretched, FCI expansions expressed in unrestricted orbitals are substantially more compact than their restricted counterparts and more compact than those expressed in split-localized orbitals. These unrestricted Hilbert spaces, however, become nonergodic toward the dissociation limit, and the total wave function may be thought of as the sum of two weakly coupled, spin-impure, functions whose energies are nonetheless very close to the exact energy. In this limit, it is a challenge for i-FCIQMC to resolve a spin-pure wave function. The use of unrestricted natural orbitals is a promising remedy for this problem, as their expansions are more strongly weighted toward lower excitations of the reference, and they provide stronger coupling to higher excitations than do UHF orbitals.

Dietary advice combined with a salicylate, mineral and vitamin supplement (CV247) has some tumour static properties: a phase II study

Purpose – This pilot study seeks to evaluate whether dietary intervention combined with an oral formulation of sodium salicylate, mineral and vitamin supplements (CV247) altered the rate of progression in patients with malignant disease.Design/methodology/approach – A total of 37 patients were recruited from March 2001 to November 2001 and ran to September 2004. All patients had progressive malignancy at trial entry (def: at least two consecutive increases in tumour markers >10 per cent or radiological progression). Patients, were recommended a diet rich in fresh fruit, vegetables, low in saturated fats, salt and man‐made chemical supplements such as colours and preservatives together with oral CV247 (sodium salicylate, copper gluconate, manganese gluconate and ascorbic acid). Dietary compliance was monitored, from a subgroup, by monthly interviews with the trial dietitian recorded on a linear analogue scale. Quality of life was measured by monthly completion of a Rotterdam symptom check‐list questionnair...

A randomised double‐blind phase II study of lifestyle counselling and salicylate compounds in patients with progressive prostate cancer

Purpose – Salicylate intake and lifestyle have been implicated in the aetiology of prostate cancer, but the purpose of this paper is to evaluate their influence on established cancer progression.Design/methodology/approach – A randomised, double blind, phase II study involving 110 men whose prostate specific antigen (PSA), had risen in three consecutive values, >20 per cent over the proceeding six months. Men were counselled to eat less saturated fat, processed food, more fruit, vegetables and legumes; exercise more regularly and to stop smoking. They were then randomised to take sodium salicylate (SS) alone or SS combined with, vitamin C, copper and manganese gluconates (CV247). Patients took this daily, without other intervention, but were withdrawn if their PSA doubling time (PSAdt) shortened or their PSA rose >20 per cent from baseline.Findings – Although there was no difference in outcome between the SS or CV247 (21 v 19 p = 0.92), the intervention slowed or stopped the rate of PSA progression in 40 ...

Cancer: the role of exercise in prevention and progression

Purpose – The papers purpose is to examine evidence for the benefits of exercise in relation to cancer development, progression and prevention.Design/methodology/approach – The reviewed literature was divided into categories according to the role exercise plays in cancer prevention and progression, during treatment, and in relapse prevention.Findings – There is now persuasive evidence that exercise improves the physical and psychological function of patients with cancer, reduces the risk of recurrence and possibly improves survival.Originality/value – Previous research highlights the importance of exercise in cancer prevention and throughout the cancer experience. However, current knowledge of the mechanisms by which physical activity may positively influence the activity of cancers is poorly understood; these mechanisms are explored in this paper.

Can dietary intervention alter prostate cancer progression

Purpose – Research has shown that dietary factors can mediate the transformation of latent prostate cancer into clinically apparent cancers. This paper aims to review the evidence from studies on nutrition and prostate cancer.Design/methodology/approach – A literature review of studies on nutrition and cancer was undertaken.Findings – The data showed that deficiencies in trace elements and vitamins may lead to an increased risk of prostate cancer.Originality/value – The paper shows that there appears to be a clear link with aspects of vitamin and mineral deficiencies and prostate cancer and the area merits more work.

Physical activity levels and barriers to exercise referral among patients with cancer

OBJECTIVE Physical activity after cancer is associated with a lower rate of adverse effects and better survival. The objectives of this study were to assess the exercise levels of people living with and beyond cancer attending a local oncology unit, and explore their attitudes to supervised exercise referral. METHODS 134 patients attending the oncology unit over a 2 month period were approached to complete a questionnaire about their exercise levels and barriers to exercise. RESULTS 12 of 114 (11%) patients were classed as active according to the General Practice Physical Activity Questionnaire. Despite receiving written and verbal explanations about the benefits of exercise, 44% of eligible patients declined exercise referral, with health concerns, time pressures, and the perception that they were already adequately exercising stated as the most common justifications. Overall, 82% met one or more of the current indications for the National Exercise Referral Scheme, so even in regions where the inclusion criteria have not been broadened to include cancer, this scheme is a practical option for most. CONCLUSION It is clear from these results that we are failing to motivate cancer patients into healthier lifestyles. PRACTICE IMPLICATIONS Further efforts are needed to determine and implement behavioural change strategies.

A double-blind, randomised trial of a polyphenolic-rich nail bed balm for chemotherapy-induced onycholysis: the UK polybalm study

PurposeNail damage is common amongst patients receiving chemotherapy causing disfigurement and pain. This investigation evaluated whether a topical balm containing steam-extracted, bioactive polyphenolic-rich herbal oils blended with organic waxes could protect the nails via their reported anti-inflammatory, analgesic, anti-oxidant and anti-microbial properties.Methods60 patients (23M, 37F) were randomised to apply (2–3/day) either the plant balm (PB) or a petroleum control (PC) to their nail beds. Demographics, type and number of chemotherapy cycles did not differ between the two groups, recruited between Sept 2015 and Sept 2016. An unpaired t test was used to test the differences in symptoms and physical nail damage between the two groups.ResultsSymptom scores recorded with the dermatology life quality questionnaire (DLQQ) were significantly better, between the start and end of chemotherapy, in the group applying the PB versus PC. Likewise, the mean fall in nail damage, scored with the Nail Psoriasis Index by the supervising physician, was also significantly different.ConclusionThe polyphenolic-rich essential oils and plant-based waxes in this nail bed balm profoundly reduced chemotherapy-related nail damage and improved nail-related quality of life, compared to a control. A further analysis is planned combining this balm with nail bed cooling.