Graphene nanoribbons grown in hBN stacks for high-performance electronics

Van der Waals encapsulation of two-dimensional materials in hexagonal boron nitride (hBN) stacks is a promising way to create ultrahigh-performance electronic devices1-4. However, contemporary approaches for achieving van der Waals encapsulation, which involve artificial layer stacking using mechanical transfer techniques, are difficult to control, prone to contamination and unscalable. Here we report the transfer-free direct growth of high-quality graphene nanoribbons (GNRs) in hBN stacks. The as-grown embedded GNRs exhibit highly desirable features being ultralong (up to 0.25 mm), ultranarrow (<5 nm) and homochiral with zigzag edges. Our atomistic simulations show that the mechanism underlying the embedded growth involves ultralow GNR friction when sliding between AA'-stacked hBN layers. Using the grown structures, we demonstrate the transfer-free fabrication of embedded GNR field-effect devices that exhibit excellent performance at room temperature with mobilities of up to 4,600 cm2 V-1 s-1 and on-off ratios of up to 106. This paves the way for the bottom-up fabrication of high-performance electronic devices based on embedded layered materials.

Theory of sigma bond resonance in flat boron materials

In chemistry, theory of aromaticity or π bond resonance plays a central role in intuitively understanding the stability and properties of organic molecules. Here we present an analogue theory for σ bond resonance in flat boron materials, which allows us to determine the distribution of two-center two-electron and three-center two-electron bonds without quantum calculations. Based on this theory, three rules are proposed to draw the Kekulé-like bonding configurations for flat boron materials and to explore their properties intuitively. As an application of the theory, a simple explanation of why neutral borophene with ~1/9 hole has the highest stability and the effect of charge doping on borophene's optimal hole concentration is provided with the assumption of σ and π orbital occupation balance. Like the aromaticity theory for carbon materials, this theory greatly deepens our understanding on boron materials and paves the way for the rational design of various boron-based materials.

Catalytic Growth of Ultralong Graphene Nanoribbons on Insulating Substrates

Graphene nanoribbons (GNRs) with widths of a few nanometers are promising candidates for future nanoelectronic applications due to their structurally tunable bandgaps, ultrahigh carrier mobilities, and exceptional stability. However, the direct growth of micrometer-long GNRs on insulating substrates, which is essential for the fabrication of nanoelectronic devices, remains an immense challenge. Here, the epitaxial growth of GNRs on an insulating hexagonal boron nitride (h-BN) substrate through nanoparticle-catalyzed chemical vapor deposition is reported. Ultranarrow GNRs with lengths of up to 10 µm are synthesized. Remarkably, the as-grown GNRs are crystallographically aligned with the h-BN substrate, forming 1D moiré superlattices. Scanning tunneling microscopy reveals an average width of 2 nm and a typical bandgap of ≈1 eV for similar GNRs grown on conducting graphite substrates. Fully atomistic computational simulations support the experimental results and reveal a competition between the formation of GNRs and carbon nanotubes during the nucleation stage, and van der Waals sliding of the GNRs on the h-BN substrate throughout the growth stage. This study provides a scalable, single-step method for growing micrometer-long narrow GNRs on insulating substrates, thus opening a route to explore the performance of high-quality GNR devices and the fundamental physics of 1D moiré superlattices.

High Temperature Accelerated Stone-Wales Transformation and the Threshold Temperature of IPR-C60 Formation

The Stone-Wales bond rotation isomerization of nonicosahedral C₆₀ (C_2v-C₆₀) into isolated-pentagon rule following icosahedral C₆₀ (I_h-C₆₀ or IPR-C₆₀) is a limiting step in the synthesis of I_h-C₆₀. However, extensive previous studies indicate that the potential energy barrier of the Stone-Wales bond rotation is between 6 and 8 eV, extremely high to allow for bond rotation at the temperatures used to produce fullerenes conventionally. This is also despite data indicating a possible fullerene road mechanism that necessitates low-temperature annealing. However, these previous investigations often have limiting factors, such as using the harmonic approximation to determine free energies at high temperatures or considering only the reverse I_h-C₆₀ to C_2v-C₆₀ transition as a basis. Indeed, when the difference in energy between I_h-C₆₀ and C_2v-C₆₀ is accounted for, this barrier is generally reduced by ∼1.5 eV. Thus, utilizing the recently developed density functional tight binding metadynamics (DFTB-MTD) interface, the effects of temperature on the bond rotation in the conversion of C_2v-C₆₀ to I_h-C₆₀ have been investigated. We found that Stone-Wales bond rotations are complex processes with both in-plane and out-of-plane transition states, and which transition path dominates depends on temperature. Our results clearly show that at temperatures of 2000 K, the free energy for a C_2v-C₆₀ to I_h-C₆₀ transition is only ∼4.21 eV and further reduces to ∼3.77 eV at 3000 K. This translates to transition times of ∼971 μs at 2000 K and ∼34 ns at 3000 K, indicating that defect healing is a fast process at temperatures typical of arc jet or laser ablation experiments. Conversely, below ∼2000 K, bond rotation becomes prohibitively slow, putting a lower threshold limit on the temperature of fullerene formation and subsequent annealing.

Nonfuel Antineutrino Contributions in the High Flux Isotope Reactor

Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of ν ¯ e is important when making theoretical predictions. One source of ν ¯ e that is often neglected arises from the irradiation of the nonfuel materials in reactors. The ν ¯ e rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible ν ¯ e sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the ν ¯ e source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel ν ¯ e contributions from HFIR to PROSPECT amount to 1% above the inverse beta decay threshold with a maximum contribution of 9% in the 1.8-2.0 MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel ν ¯ e contribution.

Borophene with Large Holes

In two-dimensional (2D) borophene, the structural transition from triangular lattice to hexagonal lattice with an increase in vacancy concentration is a basic principle of constructing various borophene isomers. Here, by performing an extensive structural search of 4239 borophene isomers with both hexagonal holes (HHs) and large holes (LHs), we show that the structural transformation from triangular lattice to borophene with large holes is energetically more favorable. Borophene isomers with LHs are more stable than those with only HHs at high vacancy concentrations (>20%) and are just slightly less stable than those with only HHs at low vacancy concentrations. This discovery greatly expands the family of 2D borophene and opens a route for synthesizing new borophene isomers.

DFTB+, a software package for efficient approximate density functional theory based atomistic simulations

DFTB+ is a versatile community developed open source software package offering fast and efficient methods for carrying out atomistic quantum mechanical simulations. By implementing various methods approximating density functional theory (DFT), such as the density functional based tight binding (DFTB) and the extended tight binding method, it enables simulations of large systems and long timescales with reasonable accuracy while being considerably faster for typical simulations than the respective ab initio methods. Based on the DFTB framework, it additionally offers approximated versions of various DFT extensions including hybrid functionals, time dependent formalism for treating excited systems, electron transport using non-equilibrium Green's functions, and many more. DFTB+ can be used as a user-friendly standalone application in addition to being embedded into other software packages as a library or acting as a calculation-server accessed by socket communication. We give an overview of the recently developed capabilities of the DFTB+ code, demonstrating with a few use case examples, discuss the strengths and weaknesses of the various features, and also discuss on-going developments and possible future perspectives.

Extraction of the ^{235}U and ^{239}Pu Antineutrino Spectra at Daya Bay

This Letter reports the first extraction of individual antineutrino spectra from ^{235}U and ^{239}Pu fission and an improved measurement of the prompt energy spectrum of reactor antineutrinos at Daya Bay. The analysis uses 3.5×10^{6} inverse beta-decay candidates in four near antineutrino detectors in 1958 days. The individual antineutrino spectra of the two dominant isotopes, ^{235}U and ^{239}Pu, are extracted using the evolution of the prompt spectrum as a function of the isotope fission fractions. In the energy window of 4-6 MeV, a 7% (9%) excess of events is observed for the ^{235}U (^{239}Pu) spectrum compared with the normalized Huber-Mueller model prediction. The significance of discrepancy is 4.0σ for ^{235}U spectral shape compared with the Huber-Mueller model prediction. The shape of the measured inverse beta-decay prompt energy spectrum disagrees with the prediction of the Huber-Mueller model at 5.3σ. In the energy range of 4-6 MeV, a maximal local discrepancy of 6.3σ is observed.

Measurement of the Electron Antineutrino Oscillation with 1958 Days of Operation at Daya Bay

We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor ν[over ¯]_{e} inverse β decay candidates observed over 1958 days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative ν[over ¯]_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3}  eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3}  eV^{2} assuming the inverted hierarchy.

Inducing regioselective chemical reactivity in graphene with alkali metal intercalation

First principles calculations demonstrate that alkali metal atoms, intercalated between metal substrates and adsorbed graphene monolayers, induce localised regions of increased reactivity. The extent of this localisation is proportional to the size of the alkali atom and the strength of the graphene-substrate interaction. Thus, larger alkali atoms are more effective (e.g. K > Na > Li), as are stronger-interacting substrates (e.g. Ni > Cu). Despite the electropositivity of these alkali metal adsorbates, analysis of charge transfer between the alkali metal, the substrate and the adsorbed graphene layer indicates that charge transfer does not give rise to the observed regioselective reactivity. Instead, the increased reactivity induced in the graphene structure is shown to arise from the geometrical distortion of the graphene layer imposed by the intercalated adsorbed atom. We show that this strategy can be used with arbitrary adsorbates and substrate defects, provided such structures are stable, towards controlling the mesoscale patterning and chemical functionalisation of graphene structures.

Hormone Synthesis by Primary Breast Carcinomas and Prognosis in Human Breast Cancer

The ability of human breast carcinomas to convert pregnenolone to progesterone and dehydroepiandrosterone to Δ4-androstene-3,17-dione (Δ4) was investigated as a potential aid for prognosis, and the following observations were recorded. 1. Neither the amounts of progesterone or Δ4 synthesized nor Δ4/progesterone ratios correlated with tumour size or lymph node involvement. 2. Δ4 synthesis was lower in carcinomas from patients who had recurrences within 2 years of mastectomy than in carcinomas from those who remained free of metastases. 3. Life table analysis of the results indicated that these parameters appeared unlikely to be useful aids for prognosis.

Effects of Opiates and Naloxone on Certain Enzymes of Carbohydrate Metabolism in Human Breast Carcinomas

The effects of administration of opiates and naloxone on the activities of PFK, 6PGDH and α-GPDH and α-GPDH/6PGDH ratios in human breast carcinomas were investigated in patients awaiting mastectomy. Injection of naloxone or fentanyl into an antecubital vein resulted in a statistically significant reduction in the activity of α-GPDH. Fentanyl was also effective in reducing the activity of 6PGDH. Injection of morphine into a branch of the internal mammary artery during mastectomy failed to induce changes in the activities of any of the enzymes but injection of naloxone resulted in a significant rise in the activity of 6PGDH. It is postulated that these alterations in the activities might not be associated with the binding of these drugs to opiate receptor proteins in the carcinoma. Furthermore opiate agonists or antagonists might not produce the required changes in the activities of any of the enzymes.

Catalytic CVD synthesis of boron nitride and carbon nanomaterials - synergies between experiment and theory

Low-dimensional carbon and boron nitride nanomaterials - hexagonal boron nitride, graphene, boron nitride nanotubes and carbon nanotubes - remain at the forefront of advanced materials research. Catalytic chemical vapour deposition has become an invaluable technique for reliably and cost-effectively synthesising these materials. In this review, we will emphasise how a synergy between experimental and theoretical methods has enhanced the understanding and optimisation of this synthetic technique. This review examines recent advances in the application of CVD to synthesising boron nitride and carbon nanomaterials and highlights where, in many cases, molecular simulations and quantum chemistry have provided key insights complementary to experimental investigation. This synergy is particularly prominent in the field of carbon nanotube and graphene CVD synthesis, and we propose here it will be the key to future advances in optimisation of CVD synthesis of boron nitride nanomaterials, boron nitride - carbon composite materials, and other nanomaterials generally.

Does anyone ever expect to die?

Patients who come to the intensive care unit are amongst the sickest patients in our hospitals. Patients can be admitted to the intensive care unit unexpectedly (following accidents or sudden onset of illness) or as unplanned but not necessarily truly 'unexpected' admissions. These patients often have significant underlying chronic health issues, including metastatic cancer, advanced cardiac, respiratory, renal, or hepatic failure, or frailty, with a high likelihood of death in the ensuing months. Using the Australian and New Zealand Intensive Care Society Clinical Trials Group Point Prevalence Program, a prospective single-day observational study across 46 Australian hospitals in 2014 and 2015, we found that less than 9% of intensive care unit patients (51/577) had an advance directive available. From these results, we provide two suggestions to increase intensive care's understanding of patients' end-of-life wishes. First, systematically target 'high risk of dying' patient groups for goals of care conversations in the outpatient setting. Such groups include those where one would not be 'surprised' if they died within a year. Second, as a society, more conversations about end-of-life wishes are needed.

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW_{th} reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective ^{239}Pu fission fractions F_{239} from 0.25 to 0.35, Daya Bay measures an average IBD yield σ[over ¯]_{f} of (5.90±0.13)×10^{-43}  cm^{2}/fission and a fuel-dependent variation in the IBD yield, dσ_{f}/dF_{239}, of (-1.86±0.18)×10^{-43}  cm^{2}/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the ^{239}Pu fission fraction at 10 standard deviations. The variation in IBD yield is found to be energy dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1σ. This discrepancy indicates that an overall deficit in the measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes ^{235}U, ^{239}Pu, ^{238}U, and ^{241}Pu. Based on measured IBD yield variations, yields of (6.17±0.17) and (4.27±0.26)×10^{-43}  cm^{2}/fission have been determined for the two dominant fission parent isotopes ^{235}U and ^{239}Pu. A 7.8% discrepancy between the observed and predicted ^{235}U yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.

Limits on Active to Sterile Neutrino Oscillations from Disappearance Searches in the MINOS, Daya Bay, and Bugey-3 Experiments

Searches for a light sterile neutrino have been performed independently by the MINOS and the Daya Bay experiments using the muon (anti)neutrino and electron antineutrino disappearance channels, respectively. In this Letter, results from both experiments are combined with those from the Bugey-3 reactor neutrino experiment to constrain oscillations into light sterile neutrinos. The three experiments are sensitive to complementary regions of parameter space, enabling the combined analysis to probe regions allowed by the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE experiments in a minimally extended four-neutrino flavor framework. Stringent limits on sin^{2}2θ_{μe} are set over 6 orders of magnitude in the sterile mass-squared splitting Δm_{41}^{2}. The sterile-neutrino mixing phase space allowed by the LSND and MiniBooNE experiments is excluded for Δm_{41}^{2}<0.8  eV^{2} at 95%  CL_{s}.

Improved Search for a Light Sterile Neutrino with the Full Configuration of the Daya Bay Experiment

This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the 2×10^{-4}≲|Δm_{41}^{2}|≲0.3  eV^{2} mass range. The resulting limits on sin^{2}2θ_{14} are improved by approx imately a factor of 2 over previous results and constitute the most stringent constraints to date in the |Δm_{41}^{2}|≲0.2  eV^{2} region.

Comparison of First- and Second-Season Palivizumab Prophylaxis in Patients with Chronic Lung Disease (CLD) in the ‘Caress’ Database (2005-2014)

BACKGROUND: Respiratory syncytial virus (RSV) related hospitaliza-tion (RSVH) rates are 10-fold higher in infants with CLD compared with healthy term infants until 24 months of age. Current pediatric advisory guidelines recommend RSV prophylaxis for CLD infants &lt; 2 years of age based on oxygen requirement for at least 28 days after birth during the first RSV season and those who continue to require chronic medical therapy for the management of CLD during the second season.

OBJECTIVES: This study compared RSVH rates in CLD infants who received palivizumab during the first RSV season (FS) versus the second season (SS) in the Canadian Registry of Palivizumab (CARESS) database.

DESIGN/METHODS: CARESS is a prospective registry of infants who received palivizumab at one of 32 sites across Canada during the 2005-2014 RSV seasons. Demographic data were collected at enrollment and respiratory-illness related hospitalization events were recorded monthly. Infants aged &lt; 24 months with CLD were enrolled.

RESULTS: 797 (55%) and 647 (45%) of 1444 CLD infants were prophy-laxed during FS and SS respectively (average age: 6.9 [FS] versus 13.6 [SS] months). SS infants had a lower gestational age [29.7 versus 31.3 weeks, F(1, 1440) = 29.9, p=&lt;0.0005] and birth weight [1447 versus 1762 grams, F(1, 1436) = 29.3, p=&lt;0.0005]. Infants prophylaxed in the SS also experienced more complicated neonatal courses with: prolonged respiratory support [63.4 versus 50.0 days, F(1, 1089) = 16.9, p=&lt;0.0005], oxygen therapy [135.7 versus 74.8 days, F(1, 1155) = 97.4, p=&lt;0.0005], and longer hospital stays [102.0 versus 72.0 days, F(1, 1369) = 62.1, p=&lt;0.0005]. RSVH rates were 2.23% (FS) and 2.66% (SS). Cox regression adjusted for daycare attendance, multiple births, gestational age, birth weight and neonatal complications found no significant differences in the time to first RSVH between FS and SS infants (Hazard ratio: 0.96, 95% CI 0.37–2.52, p=0.94).

CONCLUSION: SS infants who received RSV prophylaxis for CLD had a similar hazard of RSVH to those who only received palivizumab in the first year of life. The findings imply that FS and SS infants are correctly selected for RSV prophylaxis based on the stipulated criteria and their severity of illness and that SS infants are equally at risk for RSVH compared to FS infants.

Comparing First- and Second-Season Palivizumab Prophylaxis in Patients with Hemodynamically Significant Congenital Heart Disease (HSCHD) in the ‘Caress’ Database (2005-2014)

BACKGROUND: Compared with normal children, RSV-related hospi-talization (RSVH) rates in children with HSCHD are 2-4 fold higher even up to 2 years of age with an overall weighted mean mortality rate of 5.2%. Pediatric advisory guidelines recommend prophylaxis against respiratory syncytial virus (RSV) for infants with HSCHD. However, current recommendations cast doubt as to whether prophylaxis is beneficial beyond 1 year of age.

OBJECTIVES: To determine whether there are differences in RSVH in HSCHD infants receiving palivizumab during the first versus second RSV season in the Canadian Registry of palivizumab (CARESS).

DESIGN/METHODS: CARESS is a prospective registry of infants who received ≥1 dose of palivizumab at one of 32 sites across Canada during the 2005-2014 RSV seasons. Demographic data were collected at enrollment and respiratory-illness-related hospitalization events recorded monthly. In the event of a hospitalization, the relevant hospital records were reviewed by the site’s research nurse for detailed information on criteria for hospital-ization, length of stay (regular ward vs. ICU), days on respiratory support and/or intubation, and RSV test type and diagnosis. Infants aged &lt;24 months with cyanotic or acyanotic HSCHD were recruited.

RESULTS: 1306 (64.9%) of 2013 infants received prophylaxis only for the first season. 707 (35.1%) were prophylaxed during the second season (average age in months: 4.7 [first season] vs 14.7 [second season]). Baseline demographics for both seasons were similar. However, infants aged &gt;1year had a more complicated neonatal course, with significantly longer neonatal length of stay (46.7 versus 25.6 days). Infants received: 4.5±1.4 injections; 90.5% of their expected injections and 88.2% of their injections within the appropriate time intervals. 26 infants in the first year (RSVH rate: 2.26%) and 11 infants in the second year (RSVH rate: 2.09%) were hospitalized. Cox regression analysis showed no significant differences in hazards between infants in their first or second year of prophylaxis in the time to first RSVH (Hazard ratio: 1.4, 95%CI 0.5-4.0, p=0.52)

CONCLUSION: Infants enrolled in the CARESS database in the second RSV season had a similar hazard of RSVH as those in the first year of life. These findings suggest that infants aged &gt;1 year with HSCHD who remain unstable, are equally at risk for RSVH and merit palivizumab prophylaxis.

Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay

This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18)  cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43)  cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ∼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.

New measurement of antineutrino oscillation with the full detector configuration at Daya Bay

We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th}  ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3}  eV^{2} in the three-neutrino framework.

Search for a light sterile neutrino at Daya Bay

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.

Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Evaluation of movement and physiological demands of rugby league referees using global positioning systems tracking

The use of global positioning systems (GPS) technology within referees of any sport is limited. Therefore, the purpose of the current study was to evaluate the movement and physiological demands of professional rugby league referees using GPS tracking analysis. Time-motion analysis was undertaken on 8 referees using 5-Hz GPS devices and heart rate monitors throughout a series of Super League matches. 44 data sets were obtained with results identifying similar total distance covered between first and second half periods with a significant (P=0.004) reduction in the number of high velocity efforts performed between 5.51-7.0 m.s-1 (1st=21±8, 2nd=18±8). Mean distance covered from greatest to least distance, was 3 717±432 m, 3 009±402 m, 1 411±231 m, 395±133 m and 120±97 m for the following 5 absolute velocity classifications, respectively; 0.51-2.0 m.s-1; 2.1-4.0 m.s-1: 4.01-5.5 m.s-1; 5.51-7.0 m.s-1; <7.01 m.s-1. Heart rate was significantly (P<0.001) greater in the first (85.5±3.4% maxHR) compared to the second (82.9±3.8% maxHR) half. This highlights the intermittent nature of rugby league refereeing, consisting of low velocity activity interspersed with high velocity efforts and frequent changes of velocity. Training should incorporate interval training interspersing high velocity efforts of varying distances with low velocity activity while trying to achieve average heart rates of ~ 84% maxHR to replicate the physiological demands.

A comparative study of respiratory syncytial virus (RSV) prophylaxis in premature infants within the Canadian Registry of Palivizumab (CARESS)

We examined the dosing regimens, compliance, and outcomes of premature infants who received palivizumab within the Canadian Registry of Palivizumab (CARESS). Infants receiving ≥1 dose of palivizumab during the 2006-2011 respiratory syncytial virus (RSV) seasons were recruited across 30 sites. Respiratory illness events were captured monthly. Infants ≤32 completed weeks gestational age (GA) (Group 1) were compared to 33-35 completed weeks GA infants (Group 2) following prophylaxis. In total, 6,654 patients were analyzed (Group 1, n = 5,183; Group 2, n = 1,471). The mean GA was 29.9 ± 2.9 versus 34.2 ± 2.2 weeks for Groups 1 and 2, respectively. Group differences were significant (all p-values <0.05) for the following: proportion of males, Caucasians, siblings, multiple births, maternal smoking, smoking during pregnancy, household smokers, >5 household individuals, birth weight, and enrolment age. Overall, infants received 92.6 % of expected injections. Group 1 received significantly more injections, but a greater proportion of Group 2 received injections within recommended intervals. The hospitalization rates were similar for Groups 1 and 2 for respiratory illness (4.7 % vs. 3.7 %, p = 0.1) and RSV (1.5 % vs. 1.4 %, p = 0.3). Neither the time to first respiratory illness [hazard ratio = 0.9, 95 % confidence interval (CI) 0.7-1.2, p = 0.5] nor to first RSV hospitalization (hazard ratio = 1.3, 95 % CI 0.8-2.2, p = 0.3) were different. Compliance with RSV prophylaxis is high. Despite the higher number of palivizumab doses in infants ≤32 completed weeks GA, the two groups' respiratory illness and RSV-positive hospitalization rates were similar.