COVID-19 and tobacco cessation: lessons from India.

OBJECTIVES: The Government of India prohibited the sale of tobacco products during the COVID-19 lockdown to prevent the spread of the SARS-CoV-2 virus. This study assessed the tobacco cessation behaviour and its predictors among adult tobacco users during the initial COVID-19 lockdown period in India. METHODS: A cross-sectional study was conducted with 801 adult tobacco users (both smoking and smokeless tobacco) in two urban metropolitan cities of India over a 2-month period (July to August 2020). The study assessed complete tobacco cessation and quit attempts during the lockdown period. Logistic and negative binomial regression models were used to study the correlates of tobacco cessation and quit attempts, respectively. RESULTS: In total, 90 (11.3%) tobacco users reported that they had quit using tobacco after the COVID-19 lockdown period. Overall, a median of two quit attempts (interquartile range 0-6) was made by tobacco users. Participants with good knowledge on the harmful effects of tobacco use and COVID-19 were significantly more likely to quit tobacco use (odds ratio [OR] 2.2; 95% confidence interval [CI] 1.2-4.0) and reported more quit attempts (incidence risk ratio 5.7; 95% CI 2.8-11.8) compared to those with poor knowledge. Participants who had access to tobacco products were less likely to quit tobacco use compared to those who had no access (OR 0.3; 95% CI 0.2-0.5]. CONCLUSIONS: Access restrictions and correct knowledge on the harmful effects of tobacco use and COVID-19 can play an important role in creating a conducive environment for tobacco cessation among users.

Charge Condensation and Lattice Coupling Drives Stripe Formation in Nickelates.

Revealing the predominant driving force behind symmetry breaking in correlated materials is sometimes a formidable task due to the intertwined nature of different degrees of freedom. This is the case for La_{2-x}Sr_{x}NiO_{4+δ}, in which coupled incommensurate charge and spin stripes form at low temperatures. Here, we use resonant x-ray photon correlation spectroscopy to study the temporal stability and domain memory of the charge and spin stripes in La_{2-x}Sr_{x}NiO_{4+δ}. Although spin stripes are more spatially correlated, charge stripes maintain a better temporal stability against temperature change. More intriguingly, charge order shows robust domain memory with thermal cycling up to 250 K, far above the ordering temperature. These results demonstrate the pinning of charge stripes to the lattice and that charge condensation is the predominant factor in the formation of stripe orders in nickelates.

Design, implementation, control and optimization of single stage pilot scale reverse osmosis process.

In this paper, a single-stage pilot-scale reverse osmosis (RO) process is considered. The process is mainly used in various chemical industries such as dye, pharmaceutical, beverage, and so on. Initially, mathematical modeling of the process is to be done followed by linearization of the system. Here a dual loop construction with a master and a slave is used. The slave uses the conventional proportional integral derivative (PID) with a reference model of the RO process and the master uses the fractional order proportional integral derivative (FOPID) with a real time RO process. The slave's output is compared with output of the real time RO process to obtain the error which is in turn used to tune the master. The slave controller is tuned using Ziegler Nichols method and the error criterion such as integral absolute error (IAE), integral squared error (ISE), integral time squared error (ITSE), integral time absolute error (ITAE) are calculated and the minimum among them was chosen as the objective function for the master loop tuning. Hence the tuning of the controller becomes a whole. Therefore two optimization techniques such as particle swarm optimization (PSO) and bacterial foraging optimization algorithm (BFO) are used for the tuning of the master loop. From the calculations, the ITSE had the minimum value among the performance indices, hence it was used as the objective function for the BFO and PSO. The best-tuned values will be obtained with the use of these techniques and the best among all can be considered for various industrial applications. Finally, the performance of the process is compared with both techniques and BFO outperforms the PSO from the simulations.

Effect of a multicomponent intervention on achievement and improvements in quality-of-care indices among people with Type 2 diabetes in South Asia: the CARRS trial.

AIMS: To evaluate whether and what combinations of diabetes quality metrics were achieved in a multicentre trial in South Asia evaluating a multicomponent quality improvement intervention that included non-physician care coordinators to promote adherence and clinical decision-support software to enhance physician practices, in comparision with usual care. METHODS: Using data from the Centre for Cardiometabolic Risk Reduction in South Asia (CARRS) trial, we evaluated the proportions of trial participants achieving specific and combinations of five diabetes care targets (HbA1c <53 mmol/mol [7%], blood pressure <130/80 mmHg, LDL cholesterol <2.6 mmol/L, non-smoking status, and aspirin use). Additionally, we examined the proportions of participants achieving the following risk factor improvements from baseline: ≥11-mmol/mol (1%) reduction in HbA1c , ≥10-mmHg reduction in systolic blood pressure, and/or ≥0.26-mmol/l reduction in LDL cholesterol. RESULTS: Baseline characteristics were similar in the intervention and usual care arms. Overall, 12.3%, 29.4%, 36.5%, 19.5% and 2.2% of participants in the intervention group and 16.2%, 38.3%, 31.6%, 11.3% and 0.8% of participants in the usual care group achieved any one, two, three, four or five targets, respectively. We noted sizeable improvements in HbA1c , blood pressure and cholesterol, and found that participants in the intervention group were twice as likely to achieve improvements in all three indices at 12 months that were sustained over 28 months of the study [relative risk 2.1 (95% CI 1.5,2.8) and 1.8 (95% CI 1.5,2.3), respectively]. CONCLUSIONS: The intervention was associated with significantly higher achievement of and greater improvements in composite diabetes quality care goals. However, among these higher-risk participants, very small proportions achieved the complete group of targets, which suggests that achievement of multiple quality-of-care goals is challenging and that other methods may be needed in closing care gaps.

A lifestyle intervention programme for the prevention of Type 2 diabetes mellitus among South Asian women with gestational diabetes mellitus [LIVING study]: protocol for a randomized trial.

AIM: This study aims to determine whether a resource- and culturally appropriate lifestyle intervention programme in South Asian countries, provided to women with gestational diabetes (GDM) after childbirth, will reduce the incidence of worsening of glycaemic status in a manner that is affordable, acceptable and scalable. METHODS: Women with GDM (diagnosed by oral glucose tolerance test using the International Association of the Diabetes and Pregnancy Study Groups criteria) will be recruited from 16 hospitals in India, Sri Lanka and Bangladesh. Participants will undergo a repeat oral glucose tolerance test at 6 ± 3 months postpartum and those without Type 2 diabetes, a total sample size of 1414, will be randomly allocated to the intervention or usual care. The intervention will consist of four group sessions, 84 SMS or voice messages and review phone calls over the first year. Participants requiring intensification of the intervention will receive two additional individual sessions over the latter half of the first year. Median follow-up will be 2 years. The primary outcome is the proportion of women with a change in glycaemic category, using the American Diabetes Association criteria: (i) normal glucose tolerance to impaired fasting glucose, or impaired glucose tolerance, or Type 2 diabetes; or (ii) impaired fasting glucose or impaired glucose tolerance to Type 2 diabetes. Process evaluation will explore barriers and facilitators of implementation of the intervention in each local context, while trial-based and modelled economic evaluations will assess cost-effectiveness. DISCUSSION: The study will generate important new evidence about a potential strategy to address the long-term sequelae of GDM, a major and growing problem among women in South Asia. (Clinical Trials Registry of India No: CTRI/2017/06/008744; Sri Lanka Clinical Trials Registry No: SLCTR/2017/001; and ClinicalTrials.gov Identifier No: NCT03305939).

Pauling Entropy, Metastability, and Equilibrium in Dy_{2}Ti_{2}O_{7} Spin Ice.

Determining the fate of the Pauling entropy in the classical spin ice material Dy_{2}Ti_{2}O_{7} with respect to the third law of thermodynamics has become an important test case for understanding the existence and stability of ice-rule states in general. The standard model of spin ice-the dipolar spin ice model-predicts an ordering transition at T≈0.15 K, but recent experiments by Pomaranski et al. suggest an entropy recovery over long timescales at temperatures as high as 0.5 K, much too high to be compatible with the theory. Using neutron scattering and specific heat measurements at low temperatures and with long timescales (0.35 K/10^{6} s and 0.5 K/10^{5} s, respectively) on several isotopically enriched samples, we find no evidence of a reduction of ice-rule correlations or spin entropy. High-resolution simulations of the neutron structure factor show that the spin correlations remain well described by the dipolar spin ice model at all temperatures. Furthermore, by careful consideration of hyperfine contributions, we conclude that the original entropy measurements of Ramirez et al. are, after all, essentially correct: The short-time relaxation method used in that study gives a reasonably accurate estimate of the equilibrium spin ice entropy due to a cancellation of contributions.

Acceptability of a decision-support electronic health record system and its impact on diabetes care goals in South Asia: a mixed-methods evaluation of the CARRS trial.

AIMS: To describe physicians' acceptance of decision-support electronic health record system and its impact on diabetes care goals among people with Type 2 diabetes. METHODS: We analysed data from participants in the Centre for Cardiometabolic Risk Reduction in South Asia (CARRS) trial, who received the study intervention (care coordinators and use of a decision-support electronic health record system; n=575) using generalized estimating equations to estimate the association between acceptance/rejection of decision-support system prompts and outcomes (mean changes in HbA1c , blood pressure and LDL cholesterol) considering repeated measures across all time points available. We conducted in-depth interviews with physicians to understand the benefits, challenges and value of the decision-support electronic health record system and analysed physicians' interviews using Rogers' diffusion of innovation theory. RESULTS: At end-of-trial, participants with diabetes for whom glycaemic, systolic blood pressure, diastolic blood pressure and LDL cholesterol decision-support electronic health record prompts were accepted vs rejected, experienced no reduction in HbA1c [mean difference: -0.05 mmol/mol (95% CI -0.22, 0.13); P=0.599], but statistically significant improvements were observed for systolic blood pressure [mean difference: -11.6 mmHg (95% CI -13.9, -9.3); P ≤ 0.001], diastolic blood pressure [mean difference: -5.2 mmHg (95% CI -6.5, -3.8); P ≤ 0.001] and LDL cholesterol [mean difference: -0.7 mmol/l (95% CI -0.6, -0.8); P ≤0.001], respectively. The relative advantages and compatibility of the decision-support electronic health record system with existing clinic set-ups influenced physicians' acceptance of it. Software complexities and data entry challenges could be overcome by task-sharing. CONCLUSION: Wider adherence to decision-support electronic health record prompts could potentially improve diabetes goal achievement, particularly when accompanied by assistance from a non-physician health worker.

Association between empirically derived dietary patterns with blood lipids, fasting blood glucose and blood pressure in adults - the India migration study.

BACKGROUND: Dietary patterns (DPs) in India are heterogenous. To date, data on association of indigenous DPs in India with risk factors of nutrition-related noncommunicable diseases (cardiovascular disease and diabetes), leading causes of premature death and disability, are limited. We aimed to evaluate the associations of empirically-derived DPs with blood lipids, fasting glucose and blood pressure levels in an adult Indian population recruited across four geographical regions of India. METHODS: We used cross-sectional data from the Indian Migration Study (2005-2007). Study participants included urban migrants, their rural siblings and urban residents and their urban siblings from Lucknow, Nagpur, Hyderabad and Bangalore (n = 7067, mean age 40.8 yrs). Information on diet (validated interviewer-administered, 184-item semi-quantitative food frequency questionnaire), tobacco consumption, alcohol intake, physical activity, medical history, as well as anthropometric measurements were collected. Fasting-blood samples were collected for estimation of blood lipids and glucose. Principal component analysis (PCA) was used to identify major DPs based on eigenvalue> 1 and component interpretability. Robust standard error multivariable linear regression models were used to investigate the association of DPs (tertiles) with total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides, fasting-blood glucose (FBG), systolic and diastolic blood pressure (SBP and DBP) levels. RESULTS: Three major DPs were identified: 'cereal-savoury' (cooked grains, rice/rice-based dishes, snacks, condiments, soups, nuts), 'fruit-vegetable-sweets-snacks' (Western cereals, vegetables, fruit, fruit juices, cooked milk products, snacks, sugars, sweets) and 'animal food' (red meat, poultry, fish/seafood, eggs) patterns. High intake of the 'animal food' pattern was positively associated with levels of TC (ß = 0.10 mmol/L; 95% CI: 0.02, 0.17 mmol/L; p-trend = 0.013); LDL-C (ß = 0.07 mmol/L; 95% CI: 0.004, 0.14 mmol/L; p-trend = 0.041); HDL-C (ß = 0.02 mmol/L; 95% CI: 0.004, 0.04 mmol/L; p-trend = 0.016), FBG: (ß = 0.09 mmol/L; 95% CI: 0.01, 0.16 mmol/L; p-trend = 0.021) SBP (ß = 1.2 mm/Hg; 95% CI: 0.1, 2.3 mm/Hg; p-trend = 0.032); DBP: (ß = 0.9 mm/Hg; 95% CI: 0.2, 1.5 mm/Hg; p-trend = 0.013). The 'cereal-savoury' and 'fruit-vegetable-sweets-snacks' patterns showed no association with any parameter except for a positive association with diastolic blood pressure for high intake of 'fruits-vegetables-sweets-snacks' pattern. CONCLUSION: Our results indicate positive associations of the 'animal food' pattern with cardio-metabolic risk factors in India. Further longitudinal assessments of dietary patterns in India are required to validate the findings.

Evolution of the Fermi surface of Weyl semimetals in the transition metal pnictide family.

Topological Weyl semimetals (TWSs) represent a novel state of topological quantum matter which not only possesses Weyl fermions (massless chiral particles that can be viewed as magnetic monopoles in momentum space) in the bulk and unique Fermi arcs generated by topological surface states, but also exhibits appealing physical properties such as extremely large magnetoresistance and ultra-high carrier mobility. Here, by performing angle-resolved photoemission spectroscopy (ARPES) on NbP and TaP, we directly observed their band structures with characteristic Fermi arcs of TWSs. Furthermore, by systematically investigating NbP, TaP and TaAs from the same transition metal monopnictide family, we discovered their Fermiology evolution with spin-orbit coupling (SOC) strength. Our experimental findings not only reveal the mechanism to realize and fine-tune the electronic structures of TWSs, but also provide a rich material base for exploring many exotic physical phenomena (for example, chiral magnetic effects, negative magnetoresistance, and the quantum anomalous Hall effect) and novel future applications.

Quasiparticle Breakdown and Spin Hamiltonian of the Frustrated Quantum Pyrochlore Yb_{2}Ti_{2}O_{7} in a Magnetic Field.

The frustrated pyrochlore magnet Yb_{2}Ti_{2}O_{7} has the remarkable property that it orders magnetically but has no propagating magnons over wide regions of the Brillouin zone. Here we use inelastic neutron scattering to follow how the spectrum evolves in cubic-axis magnetic fields. At high fields we observe, in addition to dispersive magnons, a two-magnon continuum, which grows in intensity upon reducing the field and overlaps with the one-magnon states at intermediate fields leading to strong renormalization of the dispersion relations, and magnon decays. Using heat capacity measurements we find that the low- and high-field regions are smoothly connected with no sharp phase transition, with the spin gap increasing monotonically in field. Through fits to an extensive data set of dispersion relations combined with magnetization measurements, we reevaluate the spin Hamiltonian, finding dominant quantum exchange terms, which we propose are responsible for the anomalously strong fluctuations and quasiparticle breakdown effects observed at low fields.

Doping Dependence of Collective Spin and Orbital Excitations in the Spin-1 Quantum Antiferromagnet La_{2-x}Sr_{x}NiO_{4} Observed by X Rays.

We report the first empirical demonstration that resonant inelastic x-ray scattering (RIXS) is sensitive to collective magnetic excitations in S=1 systems by probing the Ni L_{3} edge of La_{2-x}Sr_{x}NiO_{4} (x=0, 0.33, 0.45). The magnetic excitation peak is asymmetric, indicating the presence of single and multi-spin-flip excitations. As the hole doping level is increased, the zone boundary magnon energy is suppressed at a much larger rate than that in hole doped cuprates. Based on the analysis of the orbital and charge excitations observed by RIXS, we argue that this difference is related to the orbital character of the doped holes in these two families. This work establishes RIXS as a probe of fundamental magnetic interactions in nickelates opening the way towards studies of heterostructures and ultrafast pump-probe experiments.

Conversion of gestational diabetes mellitus to future Type 2 diabetes mellitus and the predictive value of HbA1c in an Indian cohort.

AIM: To investigate the distribution of and risk factors for dysglycaemia (Type 2 diabetes and prediabetes) in women with previous gestational diabetes mellitus in India. METHODS: All women (n = 989) from two obstetric units in New Delhi and Hyderabad with a history of gestational diabetes were invited to participate, of whom 366 (37%) agreed. Sociodemographic, medical and anthropometric data were collected and 75-g oral glucose tolerance test were carried out. RESULTS: Within 5 years (median 14 months) of the pregnancy in which they were diagnosed with gestational diabetes, 263 (72%) women were dysglycaemic, including 119 (32%) and 144 (40%) with Type 2 diabetes and prediabetes, respectively. A higher BMI [odds ratio 1.16 per 1-kg/m2 greater BMI (95% CI 1.10, 1.28)], presence of acanthosis nigricans [odds ratio 3.10, 95% CI (1.64, 5.87)], postpartum screening interval [odds ratio 1.02 per 1 month greater screening interval 95% CI (1.01, 1.04)] and age [odds ratio 1.10 per 1-year older age 95% CI (1.04, 1.16)] had a higher likelihood of having dysglycaemia. The American Diabetes Association-recommended threshold HbA1c value of ≥ 48 mmol/mol (6.5%) had a sensitivity and specificity of 81.4 and 90.7%, respectively, for determining the presence of Type 2 diabetes postpartum. CONCLUSION: The high post-pregnancy conversion rates of gestational diabetes to diabetes reported in the present study reinforce the need for mandatory postpartum screening and identification of strategies for preventing progression to Type 2 diabetes. Use of the American Diabetes Association-recommended HbA1c threshold for diabetes may lead to significant under-diagnosis.

An hour-glass magnetic spectrum in an insulating, hole-doped antiferromagnet.

Superconductivity in layered copper oxide compounds emerges when charge carriers are added to antiferromagnetically ordered CuO(2) layers. The carriers destroy the antiferromagnetic order, but strong spin fluctuations persist throughout the superconducting phase and are intimately linked to superconductivity. Neutron scattering measurements of spin fluctuations in hole-doped copper oxides have revealed an unusual 'hour-glass' feature in the momentum-resolved magnetic spectrum that is present in a wide range of superconducting and non-superconducting materials. There is no widely accepted explanation for this feature. One possibility is that it derives from a pattern of alternating spin and charge stripes, and this idea is supported by measurements on stripe-ordered La(1.875)Ba(0.125)CuO(4) (ref. 15). Many copper oxides without stripe order, however, also exhibit an hour-glass spectrum. Here we report the observation of an hour-glass magnetic spectrum in a hole-doped antiferromagnet from outside the family of superconducting copper oxides. Our system has stripe correlations and is an insulator, which means that its magnetic dynamics can conclusively be ascribed to stripes. The results provide compelling evidence that the hour-glass spectrum in the copper oxide superconductors arises from fluctuating stripes.

All-in-all-Out Magnetic Order and Propagating Spin Waves in Sm_{2}Ir_{2}O_{7}.

Using resonant magnetic x-ray scattering we address the unresolved nature of the magnetic ground state and the low-energy effective Hamiltonian of Sm_{2}Ir_{2}O_{7}, a prototypical pyrochlore iridate with a finite temperature metal-insulator transition. Through a combination of elastic and inelastic measurements, we show that the magnetic ground state is an all-in-all-out (AIAO) antiferromagnet. The magnon dispersion indicates significant electronic correlations and can be well described by a minimal Hamiltonian that includes Heisenberg exchange [J=27.3(6) meV] and Dzyaloshinskii-Moriya interactions [D=4.9(3) meV], which provides a consistent description of the magnetic order and excitations. In establishing that Sm_{2}Ir_{2}O_{7} has the requisite inversion symmetry preserving AIAO magnetic ground state, our results support the notion that pyrochlore iridates may host correlated Weyl semimetals.

Maternal antecedents of adiposity and studying the transgenerational role of hyperglycemia and insulin (MAASTHI): a prospective cohort study : Protocol of birth cohort at Bangalore, India.

BACKGROUND: India is experiencing an epidemic of obesity-hyperglycaemia, which coincides with child bearing age for women. The epidemic can be sustained and augmented through transgenerational transmission of adiposity and glucose intolerance in women. This presents an opportunity for exploring a clear strategy for the control of this epidemic in India. We conducted a study between November 2013 and May 2015 to inform the design of a large pregnancy cohort study. Based on the findings of this pilot, we developed the protocol for the proposed birth cohort of 5000 women, the recruitment for which will start in April 2016. The protocol of the study documents the processes which aim at advancing the available knowledge, linking several steps in the evolution of obesity led hyperglycemia. METHODS: Maternal Antecedents of Adiposity and Studying the Transgenerational role of Hyperglycemia and Insulin (MAASTHI) is a cohort study in the public health facilities in Bangalore, India. The objective of MAASTHI is to prospectively assess the effects of glucose levels in pregnancy on the risk of adverse infant outcomes, especially in predicting the possible risk markers of later chronic diseases. The primary objective of the proposed study is to investigate the effect of glucose levels in pregnancy on skinfold thickness (adiposity) in infancy as a marker of future obesity and diabetes in offspring. The secondary objective is to assess the association between psychosocial environment of mothers and adverse neonatal outcomes including adiposity. The study aims to recruit 5000 pregnant women and follow them and their offspring for a period of 4 years. The institutional review board at The Indian Institute of Public Health (IIPH)-H, Bangalore, Public Health Foundation of India has approved the protocol. All participants are required to provide written informed consent. DISCUSSION: The findings from this study may help to address important questions on screening and management of high blood sugar in pregnancy. It may provide critical information on the specific determinants driving the underweight-obesity-T2DM epidemic in India. The study can inform the policy regarding the potential impact of screening and management protocols in public healthcare facilities. The public health implications include prioritising issues of maternal glycemic control and weight management and better understanding of the lifecourse determinants in the development of T2DM.

Vacancy defects and monopole dynamics in oxygen-deficient pyrochlores.

The idea of magnetic monopoles in spin ice has enjoyed much success at intermediate temperatures, but at low temperatures a description in terms of monopole dynamics alone is insufficient. Recently, numerical simulations were used to argue that magnetic impurities account for this discrepancy by introducing a magnetic equivalent of residual resistance in the system. Here we propose that oxygen deficiency is the leading cause of magnetic impurities in as-grown samples, and we determine the defect structure and magnetism in Y2Ti2O7-δ using diffuse neutron scattering and magnetization measurements. These defects are eliminated by oxygen annealing. The introduction of oxygen vacancies causes Ti(4+) to transform to magnetic Ti(3+) with quenched orbital magnetism, but the concentration is anomalously low. In the spin-ice material Dy2Ti2O7 we find that the same oxygen-vacancy defects suppress moments on neighbouring rare-earth sites, and that these magnetic distortions markedly slow down the long-time monopole dynamics at sub-Kelvin temperatures.

A stable three-dimensional topological Dirac semimetal Cd3As2.

Three-dimensional (3D) topological Dirac semimetals (TDSs) are a recently proposed state of quantum matter that have attracted increasing attention in physics and materials science. A 3D TDS is not only a bulk analogue of graphene; it also exhibits non-trivial topology in its electronic structure that shares similarities with topological insulators. Moreover, a TDS can potentially be driven into other exotic phases (such as Weyl semimetals, axion insulators and topological superconductors), making it a unique parent compound for the study of these states and the phase transitions between them. Here, by performing angle-resolved photoemission spectroscopy, we directly observe a pair of 3D Dirac fermions in Cd3As2, proving that it is a model 3D TDS. Compared with other 3D TDSs, for example, ß-cristobalite BiO2 (ref. 3) and Na3Bi (refs 4, 5), Cd3As2 is stable and has much higher Fermi velocities. Furthermore, by in situ doping we have been able to tune its Fermi energy, making it a flexible platform for exploring exotic physical phenomena.

Anisotropic local modification of crystal field levels in Pr-based pyrochlores: a muon-induced effect modeled using density functional theory.

Although muon spin relaxation is commonly used to probe local magnetic order, spin freezing, and spin dynamics, we identify an experimental situation in which the measured response is dominated by an effect resulting from the muon-induced local distortion rather than the intrinsic behavior of the host compound. We demonstrate this effect in some quantum spin ice candidate materials Pr(2)B(2)O(7) (B=Sn, Zr, Hf), where we detect a static distribution of magnetic moments that appears to grow on cooling. Using density functional theory we show how this effect can be explained via a hyperfine enhancement arising from a splitting of the non-Kramers doublet ground states on Pr ions close to the muon, which itself causes a highly anisotropic distortion field. We provide a quantitative relationship between this effect and the measured temperature dependence of the muon relaxation and discuss the relevance of these observations to muon experiments in other magnetic materials.

Linear magnetoresistance caused by mobility fluctuations in n-doped Cd(3)As(2).

Cd(3)As(2) is a candidate three-dimensional Dirac semimetal which has exceedingly high mobility and nonsaturating linear magnetoresistance that may be relevant for future practical applications. We report magnetotransport and tunnel diode oscillation measurements on Cd(3)As(2), in magnetic fields up to 65 T and temperatures between 1.5 and 300 K. We find that the nonsaturating linear magnetoresistance persists up to 65 T and it is likely caused by disorder effects, as it scales with the high mobility rather than directly linked to Fermi surface changes even when approaching the quantum limit. From the observed quantum oscillations, we determine the bulk three-dimensional Fermi surface having signatures of Dirac behavior with a nontrivial Berry phase shift, very light effective quasiparticle masses, and clear deviations from the band-structure predictions. In very high fields we also detect signatures of large Zeeman spin splitting (g∼16).

Measurement of the charge and current of magnetic monopoles in spin ice.

The transport of electrically charged quasiparticles (based on electrons or ions) plays a pivotal role in modern technology as well as in determining the essential functions of biological organisms. In contrast, the transport of magnetic charges has barely been explored experimentally, mainly because magnetic charges, in contrast to electric ones, are generally considered at best to be convenient macroscopic parameters, rather than well-defined quasiparticles. However, it was recently proposed that magnetic charges can exist in certain materials in the form of emergent excitations that manifest like point charges, or magnetic monopoles. Here we address the question of whether such magnetic charges and their associated currents-'magnetricity'-can be measured directly in experiment, without recourse to any material-specific theory. By mapping the problem onto Onsager's theory of electrolytes, we show that this is indeed possible, and devise an appropriate method for the measurement of magnetic charges and their dynamics. Using muon spin rotation as a suitable local probe, we apply the method to a real material, the 'spin ice' Dy(2)Ti(2)O(7) (refs 5-8). Our experimental measurements prove that magnetic charges exist in this material, interact via a Coulomb potential, and have measurable currents. We further characterize deviations from Ohm's law, and determine the elementary unit of magnetic charge to be 5 mu(B) A(-1), which is equal to that recently predicted using the microscopic theory of spin ice. Our measurement of magnetic charge and magnetic current establishes an instance of a perfect symmetry between electricity and magnetism.