Improved Measurement of the Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

Reactor neutrino experiments play a crucial role in advancing our knowledge of neutrinos. In this Letter, the evolution of the flux and spectrum as a function of the reactor isotopic content is reported in terms of the inverse-beta-decay yield at Daya Bay with 1958 days of data and improved systematic uncertainties. These measurements are compared with two signature model predictions: the Huber-Mueller model based on the conversion method and the SM2018 model based on the summation method. The measured average flux and spectrum, as well as the flux evolution with the ^{239}Pu isotopic fraction, are inconsistent with the predictions of the Huber-Mueller model. In contrast, the SM2018 model is shown to agree with the average flux and its evolution but fails to describe the energy spectrum. Altering the predicted inverse-beta-decay spectrum from ^{239}Pu fission does not improve the agreement with the measurement for either model. The models can be brought into better agreement with the measurements if either the predicted spectrum due to ^{235}U fission is changed or the predicted ^{235}U, ^{238}U, ^{239}Pu, and ^{241}Pu spectra are changed in equal measure.

Precision Measurement of Reactor Antineutrino Oscillation at Kilometer-Scale Baselines by Daya Bay

We present a new determination of the smallest neutrino mixing angle θ_{13} and the mass-squared difference Δm_{32}^{2} using a final sample of 5.55×10^{6} inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are sin^{2}2θ_{13}=0.0851±0.0024, Δm_{32}^{2}=(2.466±0.060)×10^{-3}  eV^{2} for the normal mass ordering or Δm_{32}^{2}=-(2.571±0.060)×10^{-3}  eV^{2} for the inverted mass ordering.

First Measurement of High-Energy Reactor Antineutrinos at Daya Bay

This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8-12 MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10 MeV is rejected with a significance of 6.2 standard deviations. A 29% antineutrino flux deficit in the prompt energy region of 8-11 MeV is observed compared to a recent model prediction. We provide the unfolded antineutrino spectrum above 7 MeV as a data-based reference for other experiments. This result provides the first direct observation of the production of antineutrinos from several high-Q_{β} isotopes in commercial reactors.

Joint Determination of Reactor Antineutrino Spectra from ^{235}U and ^{239}Pu Fission by Daya Bay and PROSPECT

A joint determination of the reactor antineutrino spectra resulting from the fission of ^{235}U and ^{239}Pu has been carried out by the Daya Bay and PROSPECT Collaborations. This Letter reports the level of consistency of ^{235}U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant ^{235}U and ^{239}Pu isotopes and improves the uncertainty of the ^{235}U spectral shape to about 3%. The ^{235}U and ^{239}Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the ^{235}U and ^{239}Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.

Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments

Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{μe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Δm_{41}^{2}, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL_{s} for Δm_{41}^{2}<13  eV^{2}. Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL_{s} for Δm_{41}^{2}<1.6 eV^{2}.

Post-glacial habitat release and incipient speciation in the genus Delphinus

The role of ecological and changing environmental factors in the radiation of species diversity is a fundamental question in evolutionary biology. Of particular interest is the potential for these factors to determine the boundary between what we would consider differentiation among populations and incipient speciation. Dolphins in the genus Delphinus provide a useful test case, exhibiting morphological variation in beak length, coloration and body size across their wide geographic distribution, and in particular among coastal and more pelagic habitats. Two species have been proposed, D. delphis and D. capensis, but morphologically similar allopatric populations are not monophyletic, indicating that the mostly coastal 'long-beaked' D. capensis form is not a single globally distributed species. However, the sympatric populations in the Eastern North Pacific currently designated as these two species are both morphologically and genetically differentiated. Here we use microsatellite DNA and mitochondrial DNA markers to investigate the evolutionary mechanisms that led to this incipient speciation event. We used coalescent and assignment methods to investigate the timing and extent of reproductive isolation. Our data indicate that although there is some level of on-going gene flow, the putative species found in the Eastern North Pacific are reciprocally monophyletic. The timing of isolation appears to be associated with regional changes in paleoceanographic conditions within the Holocene timeframe.

Phylogenetic relationships within the eared seals (Otariidae: Carnivora): implications for the historical biogeography of the family

Phylogenetic relationships within the family Otariidae were investigated using two regions of the mitochondrial genome. A 360-bp region of the cytochrome b gene was employed for the primary phylogenetic analysis, while a 356-bp segment of the control region was used to enhance resolution of the terminal nodes. Traditional classification of the family into the subfamilies Arctocephalinae (fur seals) and Otariinae (sea lions) is not supported, with the fur seal Callorhinus ursinus having a basal relationship relative to the rest of the family. This is consistent with the fossil record which suggests that this genus diverged from the line leading to the remaining fur seals and sea lions about 6 million years ago (mya). There is also little evidence to support or refute the monophyly of sea lions. Four sea lion clades and five fur seal clades were observed, but relationships among these clades are unclear. Similar genetic divergences between the sea lion clades (D(a) = 0.054-0.078), as well as between the major Arctocephalus fur seal clades (D(a) = 0.040-0.069) suggest that these groups underwent periods of rapid radiation at about the time they diverged from each other. Rapid radiations of this type make the resolution of relationships between the resulting species difficult and indicate the requirement for additional molecular data from both nuclear and mitochondrial genes. The phylogenetic relationships within the family and the genetic distances among some taxa highlight inconsistencies in the current taxonomic classification of the family.

Bidirectional cavopulmonary shunt in patients with multiple risk factors

BACKGROUND

Twenty-five patients in whom a modified Fontan operation was deferred because of multiple risk factors underwent a bidirectional cavopulmonary shunt. Two or more of the following risk factors were present in all: age less than 1 year, severe pulmonary artery distortion, impaired left ventricular function, subaortic obstruction, anomalous systemic-pulmonary venous connection, atrioventricular valve incompetence, and increased mean pulmonary artery pressure.

METHODS

Additional procedures included take-down of systemic-pulmonary artery shunt, atrial septectomy, pulmonary artery reconstruction, bulboventricular foramen enlargement, and atrioventricular valve repair.

RESULTS

There were three hospital deaths (12%). Mean follow-up is 21 months. There was no late mortality. Mean oxygen saturation increased from 71% to 83%. Results obtained from pulmonary artery reconstruction, enlargement of bulboventricular foramen, and atrioventricular valve repair were satisfactory for the patients in whom these risk factors were present preoperatively. Ventricular function also improved in the survivors in whom it was previously deteriorated, this being related to the suppression of the sources of ventricular volume overload.

CONCLUSIONS

In this risk group of patients for a modified Fontan operation, a bidirectional cavopulmonary shunt provided adequate palliation at reasonable low risk. Early bidirectional cavopulmonary shunt would minimize complications originating from systemic-pulmonary shunts such as pulmonary artery distortion and the potential harm of chronic ventricular volume overload.

Infective endocarditis in children: clinical analyses and evaluation of two diagnostic criteria

A new diagnostic schema for infective endocarditis (IE), the Duke criteria, has been compared with the previously published criteria of von Reyn in adult patients. This study was designed to analyze the clinical characteristics of a group of pediatric patients with IE and to compare the diagnostic efficiency of both sets of criteria. We reviewed retrospectively the clinical records of 38 patients, 22 with predisposing heart disease (Subgroup A) and 16 with no known cardiologic abnormality (Subgroup B). Ventricular septal defect was the most frequent preexisting heart disease (31.8%) and central venous catheters were the most frequent predisposing factor (68.7%). Comparison of the clinical features between subgroups (A vs. B) showed differences only for the presence of a new regurgitant murmur (9% vs. 44%, P < 0.05) and a hemoglobin value < or = 10 g/dl (50% vs. 94%, P < 0.05). The most frequent microorganisms isolated were viridans streptococci (36%) in Subgroup A and Staphylococcus aureus (50%) in Subgroup B. Of the 6 pathologically confirmed cases all would have been classified as clinically definite by the Duke criteria, as compared with 2 of 6 being defined as probable and one being rejected by von Reyn criteria. Of the 32 cases clinically defined 19 (59%) were classified as definite by the Duke criteria, and 11 (34%) were probable by the von Reyn criteria (difference 25%, P < 0.01). Although no case of IE was rejected by Duke criteria, 8 (25%) were rejected by von Reyn criteria (difference 25%, P < 0.01), with all 8 classified as possible by Duke criteria. We conclude that the Duke criteria were superior to the von Reyn criteria for the diagnosis of pediatric IE, including more cases as definite and significantly fewer cases as rejected.

The antineoplastic effect of vitamin D in transgenic mice with retinoblastoma

Vitamin D has been shown to inhibit growth of human retinoblastoma in tissue culture and nude mouse heterografts. We have described a heritable transgenic mouse model of retinoblastoma. The in vivo efficacy of 1,25-dihydroxycholecalciferol (vitamin D3) was examined by administering this agent to transgenic mice with retinoblastoma. Forty-six 8-10-week-old transgene-bearing mice were injected intraperitoneally for 5 wk. Experimental animals received 0.05 microgram (15 animals) or 0.025 microgram (15 animals) of vitamin D. Sixteen control animals received only a mineral oil vehicle. Eyes were enucleated at 5 mo and were examined histologically by two investigators in a masked fashion. All control animals demonstrated bilateral involvement of retinoblastoma. Four eyes in the low-dose group and six eyes in the high-dose group had no evidence of retinoblastoma. Eyes treated with vitamin D3 showed less extensive involvement of the retina by retinoblastoma. Vitamin D-treated animals demonstrated tumors confined to the retina, whereas control animals demonstrated larger tumors, more often invading the vitreous, anterior chamber, and choroid. Thus, Vitamin D inhibited the growth and local extension in a dose-dependent fashion.

Interpleural bupivacaine for postoperative analgesia following cholecystectomy: a randomized prospective study

The effect of interpleural analgesia on postoperative hospital course was analyzed ina prospective randomized study of patients undergoing cholecystectomy. Control patients were treated in the standard manner with systemic narcotics alone; catheter patients had an interpleural catheter placed at the end of surgery and, in addition, could receive systemic narcotics if necessary. The catheter group received interpleural 0.5% bupivacaine with epinephrine every six hours for a total of four injections. Thirteen patients were in each group. Pain score, pulmonary function and narcotic requirement were measured over the first postoperative day. Catheter patients had a lower average pain score (visual analog scale (VAS), 3.6 versus 5.2), decreased narcotic requirement in the recovery room and improved oxygen saturation (96% versus 93%). However, there was no statistical difference in amount of morphine (catheter, 25 +/- 14 mg; control, 31 +/- 15 mg), number of narcotic injections (catheter, 3.8 +/- 1.5; control, 3.5 +/- 1.5), forced vital capacity (catheter, 44% preoperative control, 41% preoperative), recovery room time (catheter, 129 +/- 54 minutes, control, 117 +/- 39 minutes) or total hospital stay (catheter, 4.1 +/- 0.9 days; control, 3.7 +/- 0.8 days). Analysis of hourly VAS scores following a bolus indicated that the analgesia disappeared within approximately four hours. The mean time to a request for narcotic following a bolus was 4.2 hours (excluding 17 of a potential total of 52 instances when narcotic was not requested at all). Therefore, the duration of pain relief for subcostal incisions using interpleural 0.5% bupivacaine is approximately four hours.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of regional intravenous guanethidine and reserpine in reflex sympathetic dystrophy. A controlled, randomized, double-blind crossover study

Both regional intravenous guanethidine and reserpine have been reported as effective in the treatment of reflex sympathetic dystrophy. Reserpine depletes storage of norepinephrine, and guanethidine interferes with transport of norepinephrine while depleting storage in the sympathetic nerve terminal. The purpose of this study was to compare drug efficacy in double-blind fashion. Twelve patients, 10 of whom had previous stellate or lumbar sympathetic blocks, were entered into this double-blind cross-over study. Each patient successively received 20 mg guanethidine in 50 ml 0.5% lidocaine, 1.25 mg reserpine in 50 ml 0.5% lidocaine, and 50 ml 0.5% lidocaine with a 1-week interval between medications. At the end of the study and before the code was broken, each patient had the option of continuing treatment with any of the three drugs: the patient merely asked for the first, second, or third drug. Pain assessment used verbal ordinal, numeric, and visual analog scales. Follow-up lasted for a minimum of 6 months. Changes in pain intensity for the first 3 days did not differ significantly among guanethidine, reserpine, and control groups. Pain relief from 2 to 14 months was achieved in two patients receiving reserpine, one receiving guanethidine, and none receiving lidocaine. None of the patients experienced permanent relief. No difference was found between reserpine and guanethidine.