Angular momentum generation in nuclear fission.

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum4-12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18.

Compound-Nucleus and Doorway-State Decays of ß-Delayed Neutron Emitters

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.

Competition between Allowed and First-Forbidden ß Decay: The Case of

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.

Outcomes by sex following treatment initiation with darunavir/cobicistat in a large Spanish cohort of the CODAR study (GeSIDA 9316).

BACKGROUND: Few women have been included in darunavir/cobicistat clinical development studies, and hardly any of them were antiretroviral experienced or treated with anything other than triple-based therapies. OBJECTIVES: Our aim was to increase our knowledge about women living with HIV undergoing darunavir/cobicistat-based regimens. METHODS: A multicentre (21 hospitals), retrospective study including a centrally selected random sample of HIV-1 patients starting a darunavir/cobicistat-based regimen from June 2014 to March 2017 was planned. Baseline characteristics, 24 and 48 week viral load response (<50 copies/mL), CD4+ lymphocyte count increase, time to change darunavir/cobicistat and adverse event occurrence were all compared by sex. The study was approved by each of the 21 ethics committees, and patients signed informed consent. RESULTS: Out of 761 participants, 193 were women. Similar characteristics were found for both sexes, except that the women had a longer duration of HIV infection (P = 0.001), and were less frequently pre-treated with darunavir/cobicistat in their previous regimen (P = 0.02). The main reason for using a darunavir/cobicistat-based regimen was simplification, without differences by sex, while monotherapy seems to be more frequently prescribed in women than in men (P = 0.067). The main outcomes, HIV viral load response, CD4+ lymphocyte count increase at 24 or 48 weeks, occurrence of adverse events, main reasons for changing and time to the modify darunavir/cobicistat regimen, did not show differences between the sexes. CONCLUSIONS: No sex disparities were found in the main study outcomes. These results support the use of a darunavir/cobicistat-based regimen in long-term pre-treated women. Clinical Trial.gov No. NCT03042390.

Large Impact of the Decay of Niobium Isomers on the Reactor ν[over ¯]_{e} Summation Calculations.

Even mass neutron-rich niobium isotopes are among the principal contributors to the reactor antineutrino energy spectrum. They are also among the most challenging to measure due to the refractory nature of niobium, and because they exhibit isomeric states lying very close in energy. The ß-intensity distributions of ^{100gs,100m}Nb and ^{102gs,102m}Nb ß decays have been determined using the total absorption γ-ray spectroscopy technique. The measurements were performed at the upgraded Ion Guide Isotope Separator On-Line facility at the University of Jyväskylä. Here, the double Penning trap system JYFLTRAP was employed to disentangle the ß decay of the isomeric states. The new data obtained in this challenging measurement have a large impact in antineutrino summation calculations. For the first time the discrepancy between the summation model and the reactor antineutrino measurements in the region of the shape distortion has been reduced.

Continued propagation of the CRF19_cpx variant among HIV-positive MSM patients in Spain.

Objectives: The HIV-1 CRF19_cpx genetic form has been recently associated with greater pathogenicity. We used CoRIS, a national cohort of 31 reference hospitals in Spain, to investigate the current epidemiological situation of this variant in Spain. Patients and methods: We analysed 4734 naive HIV-1-positive patients diagnosed during the 2007-15 period with an available pol gene sequence in the CoRIS resistance database. HIV-1 CRF19_cpx was ascribed through REGA3.0 and confirmed by a phylogenetic analysis. We analysed the presence of the transmission clusters of HIV-1 CRF19_cpx by maximum likelihood [with the randomized accelerated maximum likelihood (RAxML) program] and the time to the most recent common ancestor using Bayesian inference (BEAST, v. 1.7.5). Results: Nineteen patients were infected with CRF19_cpx: all were male, they had a mean age of 42.9 years (95% CI: 36.4-52.5 years), the majority were MSM [n = 18 (95%)] and of Spanish nationality [n = 16 (84.2%)] and they had high CD4+ T cell counts (∼415 cells/mm3). Fifteen patients were grouped into four different transmission clusters: two clusters (two patients each) grouped the patients from Valencia and another cluster grouped one patient from Madrid and another from Seville. We found a larger cluster that grouped nine patients from southern Spain (Malaga and Seville), of which six presented mutation G190A. We estimated the origin of all the transmission clusters to take place between 2009 and 2010. Conclusions: We demonstrate that this variant has spread in Spain in recent years among young HIV-positive MSM and we note a recent expansion in southern Spain in patients who carry mutation G190A. We alert healthcare managers to enhance preventive measures to prevent the continuous spread of HIV-1 CRF19_cpx.

Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength.

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R^{3}B/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type ^{A}O(p,2p)^{A-1}N have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry.

Strong Neutron Pairing in core+4n Nuclei.

The emission of neutron pairs from the neutron-rich N=12 isotones ^{18}C and ^{20}O has been studied by high-energy nucleon knockout from ^{19}N and ^{21}O secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay ^{19}N(-1p)^{18}C^{*}→^{16}C+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a ^{14}C core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay ^{21}O(-1n)^{20}O^{*}→^{18}O+n+n, attributed to its formation through the knockout of a deeply bound neutron that breaks the ^{16}O core and reduces the number of pairs.

First Accurate Normalization of the ß-delayed α Decay of

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.

Pharmacokinetics of tildipirosin in pig tonsils.

The penetration of antimicrobials in pig tonsils is hardly known. The objective of the study was to quantify the tildipirosin (TD) penetration in tonsils. Animals were randomly divided into six groups (control, T1, T2 (1), T2(5), T2(10), and T2(15)) of eight animals. T1 and T2 groups received a dose of 2 and 4 mg of TD/kg bw in one shot (Zuprevo® MSD Animal Health), respectively, and the control group received 2 mL of saline solution. The animals were sacrificed by intravenous administration of pentobarbital sodium 24 h after finishing the treatment for the control, T1, and T2(1) groups, whereas animals of T2(5), T2(10), and T2(15) groups were sacrificed at 5, 10, and 15 days, post-treatment, respectively. Tonsils and blood samples were taken at necropsy to obtain plasma, and the tildipirosin concentration was determined by high-performance liquid chromatography with tandem mass spectrometry detection. The concentration in plasma was always significantly lower than in tonsil. Average TD tonsil concentrations increased significantly in a dose-dependent manner, and the tonsil TD vs. plasma TD concentration ratio was approximately 75 for the doses of 2 and 4 mg of TD/kg bw at 24 h post-treatment. Moreover, the maximum concentration of tildipirosin in tonsil was observed at 1 day postadministration, and this concentration decreased gradually from this day until 15 days postadministration for the dose of 4 mg of TD/kg bw. Finally, the ratio AUCtonsil/AUCplasma was 97.9, and the T1/2 (h) was clearly higher in tonsil than in plasma.

Expression profiling of the GBP1 gene as a candidate gene for porcine reproductive and respiratory syndrome resistance.

A genomic region in pig chromosome 4 has been previously associated with higher viraemia levels and lower weight gain following porcine reproduction and respiratory syndrome virus (PRRSV) infection. The region includes the marker WUR1000125, a G>A polymorphism next to a putative polyadenylation site in the 3'-untranslated region (3'-UTR) of the guanylate-binding protein 1, interferon-induced (GBP1) gene. The protein encoded by GBP1 is a negative regulator of T-cell responses. We show here that GBP1 expression is lower in liver and tonsils of pigs carrying the WUR1000125-G allele due to differential allele expression (allele A expression is 1.9-fold higher than for allele G). We also show that the GBP1 gene has two active polyadenylation signals 421 bp apart and that polyadenylation usage is dependent on the WUR1000125 genotype. The distal site is the most prevalently used in all samples, but the presence of the A allele favours the generation of shorter transcripts from the proximal site. This is confirmed by a differential allele expression study in AG genotype liver and tonsil samples. The interaction between WUR1000125 and other mutations identified in the 5'- and 3'-UTR regions of this gene needs to be studied. In conclusion, our study indicates that the WUR1000125 mutation is associated with changes in the expression of the negative T-cell regulator GBP1 gene. However, the chromosome 4 locus for PRRSV viraemia levels and weight gain contains a cluster of four other GBP genes that remain to be studied as candidate genes for this QTL.

Studies on a suitable antibiotic therapy for treating swine brucellosis.

The aim of this work was developing effective treatments against Brucella suis biovar 2, responsible for swine brucellosis in Europe. MICs for antibiotics used classically in brucellosis and two new macrolides (tulathromycin and tildipirosin) were determined for 33 B. suis biovar 2 field and B. suis reference strains. MIC90 values ranged from 0.01 to 0.25 µg/mL. The best candidates, given alone or combined, were then evaluated in mice. Ten groups (n = 7) of BALB/c mice were inoculated (1 × 10(5) CFU/mouse) with a virulent B. suis biovar 2 field strain. All groups, excepting untreated control, were treated for 14 days with, respectively, doxycycline, dihydrostreptomycin, tulathromycin (one or two doses), or tildipirosin (one or two doses) given alone, and doxycycline combined with dihydrostreptomycin, tulathromycin, or tildipirosin. Combined tildipirosin treatment was the most effective, then selected for pig studies. Sixteen B. suis biovar 2 naturally infected sows were treated with oxytetracycline (20 mg/kg BW/daily) for 21 days. The half of these received also tildipirosin (4 mg/kg BW) in two doses with a 10-day interval. An extensive bacteriological study conducted ten days after ceasing treatments proved the efficacy of this combined oxytetracycline/tildipirosin treatment.

First observation of the unbound nucleus 15Ne.

We report on the first observation of the unbound proton-rich nucleus 15Ne. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u 17Ne. The 15Ne ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to 13O with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2- and 1- states in 14F is observed. The 15Ne ground state is shown to have a strong configuration with two protons in the (sd) shell around 13O with a 63(5)% (1s1/2)2 component.

Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation.

Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.

Pharmacokinetic/pharmacodynamic evaluation of marbofloxacin in the treatment of Haemophilus parasuis and Actinobacillus pleuropneumoniae infections in nursery and fattener pigs using Monte Carlo simulations.

This study evaluated the theoretical clinical outcome of three marbofloxacin posology regimens in two groups of pigs (weaners and fatteners) for the treatment of Actinobacillus pleuropneumoniae (App) and Haemophilus parasuis (Hp) infection and the appearance of resistant bacteria due to the antibiotic treatment. The probability of target attainment (PTA) for pharmacokinetic/pharmacodynamics (PK/PD) ratios associated with clinical efficacy and with the appearance of antimicrobial resistance for fluoroquinolones at each minimum inhibitory concentration (MIC) or mutant prevention concentration (MPC) were calculated, respectively. The cumulative fraction of response (CFR) was calculated for the three posology regimens against App and they ranged from 91.12% to 96.37% in weaners and from 93% to 97.43% in fatteners, respectively. In the case of Hp, they ranged from 80.52% to 85.14% in weaners and from 82.01% to 88.49% in fatteners, respectively. Regarding the PTA of the PK/PD threshold associated with the appearance of antimicrobial resistance, results showed that marbofloxacin would prevent resistances in most of the animals up to the MPC value of 1 µg/mL.

[Physical rehabilitation in extensively burned patients]. / Rehabilitación física en el paciente gran quemado.

The rehabilitation of the extensively burned patient aims to prevent and minimize consequences of the own lesion this is supported by three pillars: 1) postural treatment to prevent contractures; 2) kinesiotherapy to maintain/restore joint range of movement and muscle strength; 3) functional recovery. Physical therapy is essential in the multidisciplinary team. A coordinated team assures better results and positively influences the quality of life of the patients.

Whole-genome analysis of resilience based on the stability of reproduction performance during a porcine reproductive and respiratory syndrome virus outbreak in sows.

The Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is a very prevalent viral pathogen that can induce reproductive failure in infected sows. PRRSV infection can result in smaller litters, foetal death, late-term abortions and retarded growth of infected piglets. Not all sows respond equally to the infection partly due to genetic factors. In this study, we aimed to characterise the genetic variability of pig resilience to PRRSV infection by using a stability reproductive performance (SRP) index as a proxy of resilience. By comparing reproductive data from 183 sows, we selected 48 sows with extreme SRP values, measured as the difference in piglets lost at farrowings before and during a PRRSV outbreak. Short-read DNA fragments were sequenced from selected sows using an Illumina platform. The analysis of whole-genome sequencing information identified 16 genome regions associated with the SRP classification (cut-off P-value < 10-6). Functional evaluation of the positional candidates by gene-ontology identifiers and their participation in biological pathways were used to identify genes involved in virus entry and replication (vimentin, RAC1 and OAZ2) but also in immune responses from the host (IRF1, and IL4, IL5 and IL13). Importantly, genes related to chemokines, extracellular proteins and cell-to-cell junction integrity might contribute to placental microseparations, facilitating the trafficking of viral particles from sow to foetus that takes place during the pathogenesis of transplacental PRRSV infection. However, given the small number of animals in the study, these results shall need to be validated in larger populations.

Improved limit on direct α decay of the Hoyle state.

The current evaluation of the triple-α reaction rate assumes that the α decay of the 7.65 MeV, 0+ state in 12C, commonly known as the Hoyle state, proceeds sequentially via the ground state of 8Be. This assumption is challenged by the recent identification of two direct α-decay branches with a combined branching ratio of 17(5)%. If correct, this would imply a corresponding reduction in the triple-α reaction rate with important astrophysical consequences. We have used the 11B(3He,d) reaction to populate the Hoyle state and measured the decay to three α particles in complete kinematics. We find no evidence for direct α-decay branches, and hence our data do not support a revision of the triple-α reaction rate. We obtain an upper limit of 5×10(-3) on the direct α decay of the Hoyle state at 95% C.L., which is 1 order of magnitude better than a previous upper limit.