Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 97
Filter
Add more filters

Country/Region as subject
Publication year range
1.
Phys Rev Lett ; 133(7): 072502, 2024 Aug 16.
Article in English | MEDLINE | ID: mdl-39213578

ABSTRACT

Excited states in ^{10}B were populated with the ^{10}B(p,p^{'}γ)^{10}B^{*} reaction at 8.5 MeV and their γ decay was investigated via coincidence γ-ray spectroscopy. The emitted γ rays were measured using large-volume LaBr_{3}:Ce and CeBr_{3} detectors placed in anti-Compton shields. This allowed the observation of weak γ-ray transitions, such as the M3 transition between the J^{π},T=0^{+},1 isobaric analog state (IAS) and the J^{π},T=3^{+},0 ground state and the E2 transition between the J^{π},T=2_{1}^{+},0 state and the IAS, i.e., performing measurements of branching ratios at the level of λ≥10^{-4}. For the first time in ^{10}B, the competing M1 and M3 transitions from the decay of the IAS have been observed in a γ spectroscopy experiment. The experimental results are compared with ab initio no-core shell model calculation using the newest version of the local position-space chiral N^{3}LO nucleon-nucleon interaction. The calculations reproduce correctly the ordering of the bound states in ^{10}B, and are in reasonable agreement with the observed branching ratios and reduced transition probabilities.

2.
Phys Rev Lett ; 133(4): 042501, 2024 Jul 26.
Article in English | MEDLINE | ID: mdl-39121400

ABSTRACT

We investigated decays of ^{51,52,53}K at the ISOLDE Decay Station at CERN in order to understand the mechanism of the ß-delayed neutron-emission (ßn) process. The experiment quantified neutron and γ-ray emission paths for each precursor. We used this information to test the hypothesis, first formulated by Bohr in 1939, that neutrons in the ßn process originate from the structureless "compound nucleus." The data are consistent with this postulate for most of the observed decay paths. The agreement, however, is surprising because the compound-nucleus stage should not be achieved in the studied ß decay due to insufficient excitation energy and level densities in the neutron emitter. In the ^{53}K ßn decay, we found a preferential population of the first excited state in ^{52}Ca that contradicted Bohr's hypothesis. The latter was interpreted as evidence for direct neutron emission sensitive to the structure of the neutron-unbound state. We propose that the observed nonstatistical neutron emission proceeds through the coupling with nearby doorway states that have large neutron-emission probabilities. The appearance of "compound-nucleus" decay is caused by the aggregated small contributions of multiple doorway states at higher excitation energy.

3.
Phys Rev Lett ; 131(2): 022501, 2023 Jul 14.
Article in English | MEDLINE | ID: mdl-37505957

ABSTRACT

The ß decays from both the ground state and a long-lived isomer of ^{133}In were studied at the ISOLDE Decay Station (IDS). With a hybrid detection system sensitive to ß, γ, and neutron spectroscopy, the comparative partial half-lives (logft) have been measured for all their dominant ß-decay channels for the first time, including a low-energy Gamow-Teller transition and several first-forbidden (FF) transitions. Uniquely for such a heavy neutron-rich nucleus, their ß decays selectively populate only a few isolated neutron unbound states in ^{133}Sn. Precise energy and branching-ratio measurements of those resonances allow us to benchmark ß-decay theories at an unprecedented level in this region of the nuclear chart. The results show good agreement with the newly developed large-scale shell model (LSSM) calculations. The experimental findings establish an archetype for the ß decay of neutron-rich nuclei southeast of ^{132}Sn and will serve as a guide for future theoretical development aiming to describe accurately the key ß decays in the rapid-neutron capture (r-) process.

4.
Ecol Lett ; 25(2): 255-263, 2022 Feb.
Article in English | MEDLINE | ID: mdl-34854211

ABSTRACT

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.


Subject(s)
Conservation of Natural Resources , Ecosystem , Biodiversity , Fresh Water
5.
Dig Surg ; 39(1): 6-16, 2022.
Article in English | MEDLINE | ID: mdl-34875657

ABSTRACT

INTRODUCTION: Most hepato-pancreato-biliary (HPB) procedures are still performed through open approach. Incisional hernia (IH) is one of the most common complications after open surgery. To date, published data on IH after HPB surgery are scarce; therefore, the aim of this study was to assess the current evidence regarding incidence, risk factors, and prevention. METHODS: Medline/PubMed (1946-2020), EMBASE (1947-2020), and the Cochrane library (1995-2020) were searched for studies on IH in open HPB surgery. Animal studies, editorials, letters, reviews, comments, short case series and liver transplant, laparoscopic, or robotic procedures were excluded. The protocol was registered with PROSPERO (CRD42020163296). RESULTS: A total of 5,079 articles were retrieved. Eight studies were finally included for the analysis. The incidence of IH after HPB surgery ranges from 7.7% to 38.8%. The identified risk factors were body mass index, surgical site infection, ascites, Mercedes or reversed T incisions, and previous IH. Prophylactic mesh might be safe and effective. CONCLUSIONS: IH after open HPB surgery is still an important matter. Some of the risk factors are specific for the HPB operations and the incision type should be carefully considered. Randomized controlled trials are required to confirm the role of prophylactic mesh after HPB operations.


Subject(s)
Biliary Tract Surgical Procedures , Incisional Hernia , Laparoscopy , Liver Transplantation , Biliary Tract Surgical Procedures/adverse effects , Humans , Incisional Hernia/etiology , Incisional Hernia/prevention & control , Laparoscopy/methods , Liver Transplantation/adverse effects , Surgical Wound Infection/etiology
6.
Lifetime Data Anal ; 28(1): 23-39, 2022 01.
Article in English | MEDLINE | ID: mdl-35018550

ABSTRACT

We propose a nonparametric estimate of the scale-change parameter for characterizing the difference between two survival functions under the accelerated failure time model using an estimating equation based on restricted means. Advantages of our restricted means based approach compared to current nonparametric procedures is the strictly monotone nature of the estimating equation as a function of the scale-change parameter, leading to a unique root, as well as the availability of a direct standard error estimate, avoiding the need for hazard function estimation or re-sampling to conduct inference. We derive the asymptotic properties of the proposed estimator for fixed and for random point of restriction. In a simulation study, we compare the performance of the proposed estimator with parametric and nonparametric competitors in terms of bias, efficiency, and accuracy of coverage probabilities. The restricted means based approach provides unbiased estimates and accurate confidence interval coverage rates with efficiency ranging from 81% to 95% relative to fitting the correct parametric model. An example from a randomized clinical trial in head and neck cancer is provided to illustrate an application of the methodology in practice.


Subject(s)
Survival Analysis , Computer Simulation , Humans , Probability
7.
Hepatology ; 72(4): 1267-1282, 2020 10.
Article in English | MEDLINE | ID: mdl-31961955

ABSTRACT

BACKGROUND AND AIMS: Despite the availability of new-generation drugs, hepatocellular carcinoma (HCC) is still the third most frequent cause of cancer-related deaths worldwide. Cerium oxide nanoparticles (CeO2 NPs) have emerged as an antioxidant agent in experimental liver disease because of their antioxidant, anti-inflammatory, and antisteatotic properties. In the present study, we aimed to elucidate the potential of CeO2 NPs as therapeutic agents in HCC. APPROACH AND RESULTS: HCC was induced in 110 Wistar rats by intraperitoneal administration of diethylnitrosamine for 16 weeks. Animals were treated with vehicle or CeO2 NPs at weeks 16 and 17. At the eighteenth week, nanoceria biodistribution was assessed by mass spectrometry (MS). The effect of CeO2 NPs on tumor progression and animal survival was investigated. Hepatic tissue MS-based phosphoproteomics as well as analysis of principal lipid components were performed. The intracellular uptake of CeO2 NPs by human ex vivo perfused livers and human hepatocytes was analyzed. Nanoceria was mainly accumulated in the liver, where it reduced macrophage infiltration and inflammatory gene expression. Nanoceria treatment increased liver apoptotic activity, while proliferation was attenuated. Phosphoproteomic analysis revealed that CeO2 NPs affected the phosphorylation of proteins mainly related to cell adhesion and RNA splicing. CeO2 NPs decreased phosphatidylcholine-derived arachidonic acid and reverted the HCC-induced increase of linoleic acid in several lipid components. Furthermore, CeO2 NPs reduced serum alpha-protein levels and improved the survival of HCC rats. Nanoceria uptake by ex vivo perfused human livers and in vitro human hepatocytes was also demonstrated. CONCLUSIONS: These data indicate that CeO2 NPs partially revert the cellular mechanisms involved in tumor progression and significantly increase survival in HCC rats, suggesting that they could be effective in patients with HCC.


Subject(s)
Carcinoma, Hepatocellular/drug therapy , Cerium/therapeutic use , Liver Neoplasms, Experimental/drug therapy , Nanoparticles/therapeutic use , Animals , Apoptosis/drug effects , Cerium/pharmacokinetics , Humans , Lipid Metabolism/drug effects , Liver/metabolism , Liver Neoplasms, Experimental/mortality , Liver Neoplasms, Experimental/pathology , Male , Rats , Rats, Wistar , Signal Transduction/drug effects , alpha-Fetoproteins/analysis
8.
Surg Endosc ; 35(9): 5024-5033, 2021 09.
Article in English | MEDLINE | ID: mdl-32968916

ABSTRACT

BACKGROUND: Concomitant gallstones and common bile duct stones (CBDS) is a relatively frequent presentation. The optimal treatment remains controversial and the debate persists between two strategies. The one-stage approach: laparoscopic cholecystectomy with laparoscopic common bile duct exploration (LCBDE) has been shown to be equally safe and more cost-effective than the more traditional two-stage approach: endoscopic retrograde cholangiography followed by laparoscopic cholecystectomy (ERCP + LC). However, many surgeons worldwide still prefer the two-stage procedure. This survey evaluated contemporary management of CBDS in Spain and assessed the impact of surgeon and hospital factors on provision of LCBDE. METHODS: A 25-item, web-based anonymous survey was sent to general surgeons members of the Spanish Surgeons Association. Descriptive statistics were applied to summarize results. RESULTS: Responses from 305 surgeons across 173 Spanish hospitals were analyzed. ERCP is the initial approach for preoperatively suspected CBDS for 86% of surgeons. LCBDE is the preferred method for only 11% of surgeons and only 11% treat more than 10 cases per year. For CBDS discovered intraoperatively, 59% of respondents attempt extraction while 32% defer to a postoperative ERCP. The main reasons cited for not performing LCBDE were lack of equipment, training and timely availability of an ERCP proceduralist. Despite these barriers, most surgeons (84%) responded that LCBDE should be implemented in their departments. CONCLUSIONS: ERCP was the preferred approach for CBDS for the majority of respondents. There remains limited use of LCBDE despite many surgeons indicating it should be implemented. Focused planning and resourcing of both training and operational demands are required to facilitate adoption of LCBDE as option for patients.


Subject(s)
Cholecystectomy, Laparoscopic , Choledocholithiasis , Gallstones , Surgeons , Cholangiopancreatography, Endoscopic Retrograde , Choledocholithiasis/surgery , Common Bile Duct , Gallstones/complications , Gallstones/diagnostic imaging , Gallstones/surgery , Humans , Surveys and Questionnaires
9.
Phys Rev Lett ; 125(9): 092501, 2020 Aug 28.
Article in English | MEDLINE | ID: mdl-32915599

ABSTRACT

The size of a ΔK=0 M1 excitation strength has been determined for the first time in a predominantly axially deformed even-even nucleus. It has been obtained from the observation of a rare K-mixing situation between two close-lying J^{π}=1^{+} states of the nucleus ^{164}Dy with components characterized by intrinsic projection quantum numbers K=0 and K=1. Nuclear resonance fluorescence induced by quasimonochromatic linearly polarized γ-ray beams provided evidence for K mixing of the 1^{+} states at 3159.1(3) and 3173.6(3) keV in excitation energy from their γ-decay branching ratios into the ground-state band. The ΔK=0 transition strength of B(M1;0_{1}^{+}→1_{K=0}^{+})=0.008(1)µ_{N}^{2} was inferred from a mixing analysis of their M1 transition rates into the ground-state band. It is in agreement with predictions from the quasiparticle phonon nuclear model. This determination represents first experimental information on the M1 excitation strength of a nuclear quantum state with a negative R-symmetry quantum number.

10.
Phys Rev Lett ; 125(19): 192501, 2020 Nov 06.
Article in English | MEDLINE | ID: mdl-33216605

ABSTRACT

The ß decay of ^{208}Hg into the one-proton hole, one neutron-particle _{81}^{208}Tl_{127} nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z<82 quadrant of neutron-rich nuclei. While both negative and positive parity states with spin 0 and 1 are expected within the Q_{ß} window, only three negative parity states are populated directly in the ß decay. The data provide a unique test of the competition between allowed Gamow-Teller and Fermi, and first-forbidden ß decays, essential for the understanding of the nucleosynthesis of heavy nuclei in the rapid neutron capture process. Furthermore, the observation of the parity changing 0^{+}→0^{-}ß decay where the daughter state is core excited is unique, and can provide information on mesonic corrections of effective operators.

12.
Phys Rev Lett ; 121(14): 142701, 2018 Oct 05.
Article in English | MEDLINE | ID: mdl-30339438

ABSTRACT

The ^{12}C(α,γ)^{16}O reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced α width, γ_{11}, of the bound 1^{-} level in ^{16}O is particularly important to determine the cross section. The magnitude of γ_{11} is determined via sub-Coulomb α-transfer reactions or the ß-delayed α decay of ^{16}N, but the latter approach is presently hampered by the lack of sufficiently precise data on the ß-decay branching ratios. Here we report improved branching ratios for the bound 1^{-} level [b_{ß,11}=(5.02±0.10)×10^{-2}] and for ß-delayed α emission [b_{ßα}=(1.59±0.06)×10^{-5}]. Our value for b_{ßα} is 33% larger than previously held, leading to a substantial increase in γ_{11}. Our revised value for γ_{11} is in good agreement with the value obtained in α-transfer studies and the weighted average of the two gives a robust and precise determination of γ_{11}, which provides significantly improved constraints on the ^{12}C(α,γ) cross section in the energy range relevant to hydrostatic He burning.

13.
Acta Haematol ; 139(2): 132-139, 2018.
Article in English | MEDLINE | ID: mdl-29444501

ABSTRACT

We reported that PIM1 kinase is expressed in the lymphocytes of patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Quercetin, a naturally occurring flavonoid, is a dietary supplement and inhibits many kinases, including PIM1, in vitro. Under an Institutional Review Board-approved protocol, we performed an open-label, single-arm pilot study to evaluate the antitumor activity of quercetin in patients with CLL/SLL. Q-ForceTM chews were administered orally, 500 mg twice daily, for 3 months. Eligible patients had failed prior therapies, had had no other standard treatment, or refused other therapies. Response was assessed based on objective change in disease parameters. Patients were included if their lymphocyte counts were rising and ≥10,000/µL but not > 100,000/µL. Three patients received quercetin treatment. There was no toxicity. Two responded with stabilization of rising lymphocyte counts (p < 0.001 for each), which remained stable during their follow-up (5 and 11 months after cessation of treatment, respectively). The CLL cells in the nonresponder harbored a TP53 mutation. Although our data from this pilot translational study are based on a small sample, further studies of quercetin as a potential therapeutic agent in selected patients with CLL/SLL appear warranted.


Subject(s)
Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Leukemia, Lymphocytic, Chronic, B-Cell/metabolism , Proto-Oncogene Proteins c-pim-1/metabolism , Quercetin/therapeutic use , Aged , Biomarkers , Dietary Supplements , Female , Humans , Immunohistochemistry , Leukemia, Lymphocytic, Chronic, B-Cell/mortality , Middle Aged , Patient Selection , Pilot Projects , Quercetin/administration & dosage , Quercetin/adverse effects , Treatment Outcome
14.
Phys Rev Lett ; 118(16): 162502, 2017 Apr 21.
Article in English | MEDLINE | ID: mdl-28474931

ABSTRACT

A search for shape isomers in the ^{66}Ni nucleus was performed, following old suggestions of various mean-field models and recent ones, based on state-of-the-art Monte Carlo shell model (MCSM), all considering ^{66}Ni as the lightest nuclear system with shape isomerism. By employing the two-neutron transfer reaction induced by an ^{18}O beam on a ^{64}Ni target, at the sub-Coulomb barrier energy of 39 MeV, all three lowest-excited 0^{+} states in ^{66}Ni were populated and their γ decay was observed by γ-coincidence technique. The 0^{+} states lifetimes were assessed with the plunger method, yielding for the 0_{2}^{+}, 0_{3}^{+}, and 0_{4}^{+} decay to the 2_{1}^{+} state the B(E2) values of 4.3, 0.1, and 0.2 Weisskopf units (W.u.), respectively. MCSM calculations correctly predict the existence of all three excited 0^{+} states, pointing to the oblate, spherical, and prolate nature of the consecutive excitations. In addition, they account for the hindrance of the E2 decay from the prolate 0_{4}^{+} to the spherical 2_{1}^{+} state, although overestimating its value. This result makes ^{66}Ni a unique nuclear system, apart from ^{236,238}U, in which a retarded γ transition from a 0^{+} deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior.

15.
Food Microbiol ; 66: 55-63, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28576373

ABSTRACT

Outbreaks of human illness caused by enteric pathogens such as Salmonella are increasingly linked to the consumption of fruits and vegetables. Knowledge on the factors affecting Salmonella proliferation on fresh produce therefore becomes increasingly important to safeguard public health. Previous experiments showed a limited impact of pre-harvest production practices on Salmonella proliferation on tomatoes, but suggested a significant effect of harvest time. We explored the data from two previously published and one unpublished experiment using regression trees, which allowed overcoming the interpretational difficulties of classical statistical models with higher order interactions. We assessed the effect of harvest time by explicitly modeling the climatic conditions at harvest time and by performing confirmatory laboratory experiments. Across all datasets, regression trees confirmed the dominant effect of harvest time on Salmonella proliferation, with humidity-related factors emerging as the most important underlying climatic factors. High relative humidity the week prior to harvest was consistently associated with lower Salmonella proliferation. A controlled lab experiment confirmed that tomatoes containing their native epimicrobiota supported significantly lower Salmonella proliferation when incubated at higher humidity prior to inoculation. The complex interactions between environmental conditions and the native microbiota of the tomato crop remain to be fully understood.


Subject(s)
Food Contamination/analysis , Fruit/microbiology , Salmonella/growth & development , Solanum lycopersicum/microbiology , Food Handling , Fruit/growth & development , Humans , Humidity , Solanum lycopersicum/growth & development , Salmonella/classification , Salmonella/genetics , Salmonella/isolation & purification , Temperature , Time Factors
16.
J Dairy Sci ; 100(6): 4513-4527, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28365114

ABSTRACT

The aim of this study was to use meta-analytical methods to estimate effects of adding exogenous fibrolytic enzymes (EFE) to dairy cow diets on their performance and to determine which factors affect the response. Fifteen studies with 17 experiments and 36 observations met the study selection criteria for inclusion in the meta-analysis. The effects were compared by using random-effect models to examine the raw mean difference (RMD) and standardized mean difference between EFE and control treatments after both were weighted with the inverse of the study variances. Heterogeneity sources evaluated by meta-regression included experimental duration, EFE type and application rate, form (liquid or solid), and method (application to the forage, concentrate, or total mixed ration). Only the cellulase-xylanase (C-X) enzymes had a substantial number of observations (n = 13 studies). Application of EFE, overall, did not affect dry matter intake, feed efficiency but tended to increase total-tract dry matter digestibility and neutral detergent fiber digestibility (NDFD) by relatively small amounts (1.36 and 2.30%, respectively, or <0.31 standard deviation units). Application of EFE increased yields of milk (0.83 kg/d), 3.5% fat-corrected milk (0.55 kg/d), milk protein (0.03 kg/d), and milk lactose (0.05 kg/d) by moderate to small amounts (<0.30 standard deviation units). Low heterogeneity (I 2 statistic <25%) was present for yields and concentrations of milk fat and protein and lactose yield. Moderate heterogeneity (I 2 = 25 to 50%) was detected for dry matter intake, milk yield, 3.5% fat-corrected milk, and feed efficiency (kg of milk/kg of dry matter intake), whereas high heterogeneity (I 2 > 50%) was detected for total-tract dry matter digestibility and NDFD. Milk production responses were higher for the C-X enzymes (RMD = 1.04 kg/d; 95% confidence interval: 0.33 to 1.74), but were still only moderate, about 0.35 standardized mean difference. A 24% numerical increase in the RMD resulting from examining only C-X enzymes instead of all enzymes (RMD = 1.04 vs. 0.83 kg/d) suggests that had more studies met the inclusion criteria, the C-X enzymes would have statistically increased the milk response relative to that for all enzymes. Increasing the EFE application rate had no effect on performance measures. Application of EFE to the total mixed ration improved only milk protein concentration, and application to the forage or concentrate had no effect. Applying EFE tended to increase dry matter digestibility and NDFD and increased milk yield by relatively small amounts, reflecting the variable response among EFE types.


Subject(s)
Animal Feed , Dietary Fiber/metabolism , Dietary Supplements , Digestion/drug effects , Enzymes/administration & dosage , Milk/metabolism , Animals , Cattle , Cellulase/administration & dosage , Dairying , Diet , Digestion/physiology , Eating/drug effects , Endo-1,4-beta Xylanases/administration & dosage , Female , Glycolipids/metabolism , Glycoproteins/drug effects , Glycoproteins/metabolism , Lactation , Lipid Droplets , Milk Proteins/metabolism
17.
Acta Endocrinol (Buchar) ; 13(1): 106-110, 2017.
Article in English | MEDLINE | ID: mdl-31149156

ABSTRACT

INTRODUCTION: The polyglandular autoimmune syndrome (PAS) type III is a rare condition defined as the coexistence of autoimmune thyroid disorder with other endocrine autoimmune diseases, including type 1 diabetes, without adrenal dysfunction. PAS may associate with other non-endocrine autoimmune diseases, overlapping with the multiple autoimmune syndromes (MAS). We present a case of PAS III/ MAS type 3, including autoimmune thyroiditis, autoimmune diabetes, vitiligo, lupus erythematosus, associated with adult-onset atopic dermatitis, a combination not reported previously. CASE REPORT: A 40 years old woman, registered as nurse working in dialysis unit, previously diagnosed with vitiligo, euthyroid autoimmune thyroiditis and disseminated granuloma annulare, with personal and familial history of atopic disorders, presented in our clinic for disseminated eczematous and lichenoid cutaneous rashes. She was tested positive for antinuclear, anti-double stranded DNA and anti-histone antibodies, with inflammatory syndrome and marginal lymphopenia and she was diagnosed with systemic lupus erythematosus (SLE). Subsequently, moderate hyperglycemia, positive anti-glutamic acid decarboxylase antibodies and low C-peptide level prompted the diagnosis of autoimmune diabetes. Recurrent flexural eczematous rashes, with negative epicutaneous tests but positive specific IgE tests for common allergens fulfilled the clinical criteria for the diagnosis of atopic dermatitis. The clinical, immunological and glycemic status were controlled with low doses of oral prednisone (<0.5 mg/kg), methotrexate (10mg/week), antimalarials, metformin, emollients and photoprotection. After changing her workplace, the immunosuppressive treatment could be discontinued, and the patient maintained normal immunological and biochemical profile at 6 months follow-up.This case brings a unique perspective on the evolution, associations spectrum and the management challenges of endocrine polyautoimmunity associated with atopic diathesis.

18.
Phys Rev Lett ; 116(18): 182501, 2016 May 06.
Article in English | MEDLINE | ID: mdl-27203316

ABSTRACT

The N=48 ^{80}Ge nucleus is studied by means of ß-delayed electron-conversion spectroscopy at ALTO. The radioactive ^{80}Ga beam is produced through the isotope separation on line photofission technique and collected on a movable tape for the measurement of γ and e^{-} emission following ß decay. An electric monopole E0 transition, which points to a 639(1) keV intruder 0_{2}^{+} state, is observed for the first time. This new state is lower than the 2_{1}^{+} level in ^{80}Ge, and provides evidence of shape coexistence close to one of the most neutron-rich doubly magic nuclei discovered so far, ^{78}Ni. This result is compared with theoretical estimates, helping to explain the role of monopole and quadrupole forces in the weakening of the N=50 gap at Z=32. The evolution of intruder 0_{2}^{+} states towards ^{78}Ni is discussed.

19.
Appl Environ Microbiol ; 81(13): 4376-87, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25911476

ABSTRACT

Irrigation water has been implicated as a likely source of produce contamination by Salmonella enterica. Therefore, the distribution of S. enterica was surveyed monthly in irrigation ponds (n = 10) located within a prime agricultural region in southern Georgia and northern Florida. All ponds and 28.2% of all samples (n = 635) were positive for Salmonella, with an overall geometric mean concentration (0.26 most probable number [MPN]/liter) that was relatively low compared to prior reports for rivers in this region. Salmonella peaks were seasonal; the levels correlated with increased temperature and rainfall (P < 0.05). The numbers and occurrence were significantly higher in water (0.32 MPN/liter and 37% of samples) than in sediment (0.22 MPN/liter and 17% of samples) but did not vary with depth. Representative isolates (n = 185) from different ponds, sample types, and seasons were examined for resistance to 15 different antibiotics; most strains were resistant to streptomycin (98.9%), while 20% were multidrug resistant (MDR) for 2 to 6 antibiotics. DiversiLab repetitive extragenic palindromic-element sequence-based PCR (rep-PCR) revealed genetic diversity and showed 43 genotypes among 191 isolates, as defined by >95% similarity. The genotypes did not partition by pond, season, or sample type. Genetic similarity to known serotypes indicated Hadar, Montevideo, and Newport as the most prevalent. All ponds achieved the current safety standards for generic Escherichia coli in agricultural water, and regression modeling showed that the E. coli level was a significant predictor for the probability of Salmonella occurrence. However, persistent populations of Salmonella were widely distributed in irrigation ponds, and the associated risks for produce contamination and subsequent human exposure are unknown, supporting continued surveillance of this pathogen in agricultural settings.


Subject(s)
Agricultural Irrigation , Ponds/microbiology , Salmonella enterica/isolation & purification , Anti-Bacterial Agents/pharmacology , Bacterial Load , Drug Resistance, Bacterial , Florida , Genetic Variation , Genotype , Georgia , Microbial Sensitivity Tests , Molecular Typing , Salmonella enterica/classification , Salmonella enterica/drug effects , Salmonella enterica/genetics , Seasons
20.
Food Microbiol ; 46: 139-144, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25475277

ABSTRACT

Raw produce is increasingly recognized as a vehicle of human gastroenteritis. Non-typhoidal Salmonella, pathogenic Escherichia coli, and other human pathogens have been isolated from fruits and vegetables in the field and in the marketplace, which led to the hypothesis that these microbes can use plants as alternate hosts. However, environmental and physiological factors that facilitate persistence of these bacteria in the crop production environment and make produce more vulnerable to post-harvest contamination have not been fully delineated. This study tested the effect of irrigation regimes on the susceptibility of peppers and tomatoes to post-harvest proliferation of Salmonella. The experiments were carried out over three experimental seasons in two locations using seven strains of Salmonella. The irrigation regime per se did not affect susceptibility of tomatoes and peppers to post-harvest proliferation of Salmonella; however, in some of the seasons, irrigation regime-dependent differences were observed. Red peppers and tomatoes were more conducive to proliferation of Salmonella than green fruit in all seasons. Inter-seasonal differences were the strongest factors affecting proliferation of Salmonella in peppers.


Subject(s)
Agricultural Irrigation/methods , Capsicum/microbiology , Salmonella enterica/growth & development , Solanum lycopersicum/microbiology , Vegetables/microbiology , Capsicum/growth & development , Food Contamination/analysis , Fruit/growth & development , Fruit/microbiology , Solanum lycopersicum/growth & development , Seasons , Vegetables/growth & development
SELECTION OF CITATIONS
SEARCH DETAIL