Role Of Pairs Research Articles

Role of pairing on transitional nuclei of the astrophysical interest

Role of pairing on transitional nuclei of the astrophysical interest

Subradiance in dilute atomic ensembles: Role of pairs and multiple scattering

We study numerically the slow (subradiant) decay of the fluorescence of motionless atoms after a weak pulsed excitation. We show that, in the linear-optics regime and for an excitation detuned by several natural linewidths, the slow decay rate can be dominated by close pairs of atoms (dimers) forming superradiant and subradiant states. However, for a large-enough resonant optical depth and at later time, the dynamics is dominated by collective many-body effects. In this regime, we study the polarization and the spectrum of the emitted light, as well as the spatial distribution of excitation inside the sample, as a function of time during the decay dynamics. The behavior of these observables is consistent with what would be expected for radiation trapping of nearly resonant light. This finding sheds light on subradiance in dilute samples by providing an interpretation based on the light behavior of the system (multiple scattering) which is complementary to the more commonly used picture of the collective atomic Dicke state.

Possible dual bubble-like structure predicted by the relativistic Hartree–Bogoliubov model

Experimental observation of [Formula: see text]Si as a proton bubble nuclei has heated up the interest in the study of exotic bubble shaped nuclei. In this work, some of the potential doubly bubble-like (for proton as well as neutron both simultaneously) cases have been explored using relativistic Hartree–Bogoliubov (RHB) in light mass region, specially around N or [Formula: see text]. Further, the role of pairing and the evolution of new shell gaps around [Formula: see text] or [Formula: see text] and 34 have been investigated, as one moves toward drip lines. This study suggests that the occupancies/vacancies of neutron/proton orbitals for lower angular momentum state plays major role in nuclear structure to create bubble-like structure and [Formula: see text]O[Formula: see text], [Formula: see text]Mg8 and [Formula: see text]Si[Formula: see text] may have dual bubble-like structures.

The Association of SYCP3 T657C Polymorphism with Early Pregnancy Loss in Russian Women

Background. Aneuploidy is a consequence of the chromosome nondisjunction. Majority of aneuploid embryos die in utero between the 6th and 10th week, resulting in early pregnancy loss of approximately 15% of all clinically recognized pregnancies. SYCP3 plays an important role in pairing and recombination of homologous chromosomes in meiosis I, and it has been shown that the lack of this gene leads to sterility in male and subfertility in female mice due to chromosome nondisjunction. So SYCP3 is a candidate gene to evaluate the hypothesis of fetal aneuploidy arisen from meiosis gene mutations as a cause for human early pregnancy loss. Methods. In our study, the SYCP3 T657C polymorphism in 100 Russian women with early pregnancy loss (EPL) that were classified into 2 subgroups: with sporadic pregnancy loss (SPL, n=50) and recurrent pregnancy loss (RPL, n=50), as well as 56 normal fertile women (control), was examined to determine whether there is an association between the polymorphism and early pregnancy loss in Russian population. Genomic DNA was extracted from peripheral blood samples using the standard procedure of a commercially available kit. Genotyping of SYCP3 gene was determined by allele-specific polymerase chain reaction method. Data were analyzed using SPSS statistical software version 22. The chi-square test and Fisher’s exact test were used to compare genotype and allele frequencies between analyzed groups. The odds ratio (OR) and 95% confidence intervals (CI) were used for risk estimation. Results. Frequency of the heterozygous genotype (CT) was significantly higher in the group of women with early pregnancy loss as well as in women with sporadic pregnancy loss (p<0.05). In women with RPL, we found that the frequency of this genotype tended to increase but could not make a significant difference when compared with the control group. Conclusion. Our findings postulate that the T657C polymorphism of the SYCP3 gene is possibly associated with a sporadic early pregnancy loss. Актуальность. Анеуплоидия возникает вследствие нарушения расхождения хромосом, и большинство анеуплоидных эмбрионов погибают до 10 недели гестации, что приводит к потере на ранних сроках приблизительно 15% клинически диагностированных беременностей. Белок SYCP3 играет важную роль в конъюгации и рекомбинации гомологичных хромосом в первом мейотическом делении. Было показано, что отсутствие гена данного белка у мышей приводит к стерильности самцов и снижению фертильности самок вследствие нарушения расхождения хромосом. В этой связи SYCP3 можно рассматривать в качестве кандидатного гена для оценки гипотезы о фетальной анеуплоидии, возникающей в результате мутаций генов, продукты которых участвуют в мейозе, и ведущей к ранним репродуктивным потерям. Методы. В представленной работе был исследован полиморфизм Т657С гена SYCP3 у 100 женщин русской национальности с ранними репродуктивными потерями, подразделенных на две подгруппы: со спорадической потерей беременности (n=50) и привычным невынашиванием (n=50), а также у 56 фертильных женщин (контроль). Целью работы явилось изучение наличия ассоциации между данным полиморфизмом и ранними репродуктивными потерями в русской популяции. Геномная ДНК была выделена из периферической крови, генотипирование выполнялось с использованием аллель-специфической полимеразной цепной реакции. Для сравнения частот генов и генотипов в изучаемых группах применялись критерий Хи-квадрат и точный тест Фишера, для определения которых использовалось программное обеспечение SPSS Statistics, версия 22. Оно также было использовано для расчета отношения шансов (OR) и 95% доверительного интервала. Результаты. Частота гетерозиготного генотипа СТ была достоверно выше в группе женщин с ранними репродуктивными потерями и, в частности, в подгруппе со спорадической потерей беременности (р<0,05). Несмотря на тенденцию к увеличению частоты данного генотипа у женщин с привычным невынашиванием, статистически значимых отличий от контроля обнаружено не было. Заключение. Полученные результаты позволяют предполагать наличие ассоциации между полиморфизмом Т657С гена SYCP3 и спорадической потерей беременности на ранних сроках.

Pairing from dynamically screened Coulomb repulsion in bismuth

Recently, Prakash et. al. have discovered bulk superconductivity in single crystals of bismuth, which is a semi metal with extremely low carrier density. At such low density, we argue that conventional electron-phonon coupling is too weak to be responsible for the binding of electrons into Cooper pairs. We study a dynamically screened Coulomb interaction with effective attraction generated on the scale of the collective plasma modes. We model the electronic states in bismuth to include three Dirac pockets with high velocity and one hole pocket with a significantly smaller velocity. We find a weak coupling instability, which is greatly enhanced by the presence of the hole pocket. Therefore, we argue that bismuth is the first material to exhibit superconductivity driven by retardation effects of Coulomb repulsion alone. By using realistic parameters for bismuth we find that the acoustic plasma mode does not play the central role in pairing. We also discuss a matrix element effect, resulting from the Dirac nature of the conduction band, which may affect $T_c$ in the $s$-wave channel without breaking time-reversal symmetry.

A phase I study of mFOLFOX6 and ADI-PEG-20 in patients (pts) with advanced hepatocellular carcinoma (HCC) and other gastrointestinal (GI) malignancies.

384 Background: ADI-PEG-20 (pegylated arginine deiminase), an arginine degrading enzyme, and FOLFOX each exhibit clinical activity in a HCC pt subset. Preclinical data indicate that arginine depletion interferes with folate and pyrimidine metabolism as well as DNA damage repair pathways, suggesting a role for pairing AGI-PEG-20 with cytotoxic chemotherapy. Methods: This is a single center phase 1 trial of mFOLFOX-6 and ADI-PEG-20 in treatment-refractory advanced GI tumors to assess safety and tolerability, and to identify the recommended phase 2 dose (R2PD). mFOLFOX6 was administered intravenously biweekly at standard fixed doses and ADI-PEG-20 intramuscularly weekly at 18 or 36 mg/m2. Toxicity was assessed by CTCAE v4.03 and efficacy by RECIST v1.1. A HCC RP2D expansion was completed to explore efficacy. Serum arginine, citrulline, and anti-ADI-PEG-20 antibodies were monitored every other week. Results: 17 pts were treated—7 pts with GI tumors in dose escalation and 10 HCC pts in RP2D dose expansion. Histologies included HCC (13), pancreatic (3) and fibrolamellar carcinoma (1). All HCC pts had Child-Pugh A liver function and had progressed on sorafenib. Treatment-related grade ≥ 3 laboratory adverse events (AEs) occurred in 47% of pts, including neutropenia (4), thrombocytopenia (3), anemia (2), lymphocytopenia (2) and hyponatremia (1). Treatment-related grade ≥ 3 clinical AEs occurred in 2 pts, notably grade 3 fatigue and a grade 3 cardiac event not otherwise specified. No dose limiting toxicities, treatment-related deaths, or cases of hepatic failure were observed. Efficacy data for the 13 HCC pts revealed 3 (23%) PR, 6 (46%) SD, 3 PD and 1 NE. Arginine levels were depleted with therapy (mean ± SEM: baseline 85.3 ± 13.0 uM, 8 wks 4 ± 3.0 uM, 16 wk 1.1 ± 0.8uM). Anti-ADI-PEG-20 antibodies were not detected at 8 weeks (mean ± SEM: baseline 0.7 ± 0.5, 8 wks 1.5 ± 1). Conclusions: Concurrent mFOLFOX6 plus ADI-PEG-20 intramuscularly at 36 mg/m2 weekly shows an acceptable safety profile with rapid and durable reduction in serum arginine. Further evaluation of this combination is warranted in advanced HCC pts. Clinical trial information: NCT02102022.

Systematic nuclear structure studies using relativistic mean field theory in mass region A ∼ 130

Nuclear structure studies for even–even nuclei in the mass region , have been performed, with a special focus around N or Z = 64. On the onset of deformation and lying between two closed shell, these nuclei have attracted attention in a number of studies. A revisit to these experimentally accessible nuclei has been made via the relativistic mean field. The role of pairing and density depletion in the interior has been specially investigated. Qualitative analysis between two versions of relativistic mean field suggests that there is no significant difference between the two approaches. Moreover, the role of the filling orbital in density depletion towards the centre has been found to be consistent with our earlier work on the subject Shukla and Åberg (2014 Phys. Rev. C 89 014329).

Solitonic excitations in collisions of superfluid nuclei a qualitatively new phenomenon distinct from the Josephson effect

Recently, we have reported a novel role of pairing in low-energy heavy ion reactions at energies above the Coulomb barrier, which may have a detectable impact on reaction outcomes, such as the kinetic energy of fragments and the fusion cross section [arXiv:1611.10261, arXiv:1702.00069]. The phenomenon mimics the one studied experimentally with ultracold atomic gases, where two clouds of fermionic superfluids with different phases of the pairing fields are forced to merge, inducing various excitation modes of the pairing field. Although it originates from the phase difference of the pairing fields, the physics behind it is markedly different from the so-called Josephson effect. In this short contribution, we will briefly outline the results discussed in our recent papers and explain relations with the field of ultracold atomic gases.

Effects of pair bonding on dopamine D1 receptors in monogamous male titi monkeys (Callicebus cupreus).

Pair bonding leads to increases in dopamine D1 receptor (D1R) binding in the nucleus accumbens of monogamous prairie voles. In the current study, we hypothesized that there is similar up-regulation of D1R in a monogamous primate, the titi monkey (Callicebus cupreus). Receptor binding of the D1R antagonist [11 C]-SCH23390 was measured in male titi monkeys using PET scans before and after pairing with a female. We found that within-subject analyses of pairing show significant increases in D1R binding in the lateral septum, but not the nucleus accumbens, caudate, putamen, or ventral pallidum. The lateral septum is involved in a number of processes that may contribute to social behavior, including motivation, affect, reward, and reinforcement. This region also plays a role in pair bonding and paternal behavior in voles. Our observations of changes in D1R in the lateral septum, but not the nucleus accumbens, suggest that there may be broadly similar dopaminergic mechanisms underlying pair bonding across mammalian species, but that the specific changes to neural circuitry differ. This study is the first research to demonstrate neuroplasticity of the dopamine system following pair bonding in a non-human primate; however, substantial variability in the response to pairing suggests the utility of further research on the topic.

Memory response to oxytocin predicts relationship dissolution over 18 months

BackgroundOxytocin is known for its role in pair bonding in non-human animals. To examine the role of oxytocin in human romantic bonding, we examined its effect on recall of memories of past and current romantic experiences as predictors of relationship dissolution. MethodIn a placebo-controlled, within-subject, randomized experiment, 48 participants (24♀; 16 single) self-administered intranasal oxytocin and completed an autobiographical memory test. Participants in a current romantic relationship reported on their relationship status 18 months later. ResultsParticipants in a relationship recalled fewer memories of past romantic partners following oxytocin administration relative to placebo. Participants who responded to oxytocin by recalling more conflict memories of their current romantic partner, relative to placebo, were more likely to have ended their relationship over 18 months than those who did not show this response. ConclusionThese results suggest that the memory response to an intranasal oxytocin challenge may represent an index of relationship outcome over time.

The T657C polymorphism on the SYCP3 gene is associated with recurrent pregnancy loss.

SYCP3 (Sinaptonemal complex protein 3) plays a critical role in pairing and recombination of homologous chromosomes in meiosis 1. It has been shown that lack of this gene leads to infertility in male and weakened fertility in female mice. In a case-control study, we investigated the SYCP3T657C polymorphism in the genome of 100 Iranian women with recurrent pregnancy losses of unknown causes as well as 100 control samples of normal fertile women having at least one healthy child. The general aim of our study was to determine whether there is a relationship between genetic changes in the SYCP3 gene and recurrent pregnancy loss in human or not. Frequency of the heterozygous genotype and mutated allele C were significantly higher in women with recurrent pregnancy losses (P-value < 0.005). Our findings suggest that the T657C polymorphism of the SYCP3 gene is possibly associated with recurrent pregnancy loss of unknown cause in human.

Role of pairing in the description of giant monopole resonances

We compare the results obtained in the framework of the quasiparticle random phase approximation (QRPA) on top of a Hartree-Fock-Bogoliubov (HFB) with the most recent experiments on giant monopole resonances in Pb, Sn, Zr, Sm, Mo and Cd. Our calculations are fully self consistent and the density dependence of pairing interactions is, for the first time in this framework, properly taken into account. In the particle-hole (ph) channel we employ different Skyrme functionals (SLy5, SkM* and Skxs20) while in the particle-particle (pp) channel we make use of density dependent contact interactions. We introduce in the pp channel the recently proposed contact interactions which take into account the neutron-proton asymmetry. We find that no single parametrization is able to reproduce with sufficient accuracy all the nuclei. Since about two-thirds of the nuclei under investigation are better explained with a soft parametrization, this tends to suggest that the currently accepted picture for the incompressibility might require modifications.

Quantitative Analysis of Cohesin Complex Stoichiometry and SMC3 Modification-Dependent Protein Interactions

Cohesin is a protein complex that plays an essential role in pairing replicated sister chromatids during cell division. The vertebrate cohesin complex consists of four core components including structure maintenance of chromosomes proteins SMC1 and SMC3, RAD21, and SA2/SA1. Extensive research suggests that cohesin traps the sister chromatids by a V-shaped SMC1/SMC3 heterodimer bound to the RAD21 protein that closes the ring. Accordingly, the single "ring" model proposes that two sister chromatids are trapped in a single ring that is composed of one molecule each of the 4 subunits. However, evidence also exists for alternative models. The hand-cuff model suggests that each sister chromatid is trapped individually by two rings that are joined through the shared SA1/SA2 subunit. We report here the determination of cohesin subunit stoichiometry of endogenous cohesin complex by quantitative mass spectrometry. Using qConCAT-based isotope labeling, we show that the cohesin core complex contains equimolar of the 4 core components, suggesting that each cohesin ring is closed by one SA1/SA2 molecule. Furthermore, we applied this strategy to quantify post-translational modification-dependent cohesin interactions. We demonstrate that quantitative mass spectrometry is a powerful tool for measuring stoichiometry of endogenous protein core complex.

The Role of Pair and Group Work in Language Teaching

The Role of Pair and Group Work in Language Teaching

In vitro and in vivo evaluation of small interference RNA‐mediated gynaecophoral canal protein silencing in Schistosoma japonicum

BackgroundSchistosomiasis causes liver and intestinal damage and can be very debilitating. The pairing of a male worm with a female worm residing in the gynaecophoral canal of male plays a critical role in the development of female parasite. Because the male specific gynaecophoral canal protein of Schistosoma japonicum (SjGCP) is found in significant quantities in the adult female worm after pairing, it could play an important role in parasite pairing.MethodsIn the present study, three small interfering (si)RNA duplexes targeting the SjGCP gene were designed, synthesized and the silencing effects were evaluated in vitro as well as in mice infected with S. japonicum in vivo.Results In vitro studies using semi‐quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) and real‐time RT‐PCR revealed the reduction of SjGCP at the transcript level. Similarly, western blotting and immunofluorescence studies showed its reduction at the protein level after treatment of parasites with siRNAs. At a concentration of 200 nm, two siRNAs totally abolished the parasite pairing. To evaluate such a pairing inhibitory effect in vivo, mice infected with S. japonicum were treated with siRNA and both parasite pairing and burden were evaluated. In vivo tests confirmed the in vitro silencing effect of SjGCP siRNA and revealed that the systemic delivery of siRNA significantly inhibited early parasite pairing and the associated burden.ConclusionsOur preliminary results demonstrated that the SjGCP plays an important role in pairing and subsequent development in S. japonicum, and its silencing might have potential as a therapeutic approach for controlling schistosomiasis. Copyright © 2009 John Wiley & Sons, Ltd.

Vertical structure of hyper-accreting disks and consequences for gamma-ray burst outflows

We discuss the physics of the power source for gamma-ray bursts (GRBs). There is a great variety of stellar systems proposed as progenitors of long and short GRBs, but any current model for the engine ultimately involves the formation of a hyper-accreting disk around a newly-formed black hole of a few solar masses. The study of such disks can shed light onto the burst composition and energy content. We present preliminary results from disk vertical structure calculations. These include neutrino transport, a height-dependent determination of the nuclear composition, and a simplified treatment of turbulent mixing. We find that vertical mixing is rapid enough to largely erase compositional gradients, and as a consequence the upper layers of the disk reflect the neutron-rich composition of the midplane close to the black hole. We review the implications of this for the nuclear composition of outflows in GRBs. Our models suggest an increasing role for pairs in the upper regions of the disk, and we speculate that a pair-driven wind could be a significant source of cooling.

Electron–phonon interaction in the strongly correlated Hubbard model

We study numerically the renormalization of the on-site electron–phonon interaction or vertex as a function of temperature and hole doping density in the two-dimensional strongly correlated Hubbard model. In the underdoped region, we find that the forward scattering process increases monotonically with lowering temperature, whereas the backward scattering process shows little temperature dependence. With decreasing hole doping density, the electron–phonon vertex increases at small phonon momentum transfer, but decreases at large phonon momentum transfer, leading to a pronounced forward scattering peak in the small doping region. Our findings indicate that the electron–phonon interaction is strong in the high- T c superconductors and may play an important role in pairing and low-energy renormalization of quasiparticles.

Dopamine and monogamy

Social attachments play a central role in human society. In fact, such attachments are so important that deficits in the ability to form meaningful social bonds are associated with a variety of psychological disorders. Although mother–infant bonding has been studied for many years, we only recently have begun to examine the processes that underlie social bonds between adults. Over the past decade, central dopamine has become a focus of such research, especially its role in pair bonding between mates in species that display monogamous life strategies. Neuroanatomical and pharmacological studies in rodents have firmly established central dopamine systems, especially the mesocorticolimbic dopamine circuitry, in the formation, expression, and maintenance of monogamous pair bonds. As this research has progressed, it has become apparent that there is considerable overlap between the processes that underlie pair bonding and those that mediate responses to abused substances. This suggests that social bonding and substance abuse each may affect the other. Herein we review the current state of knowledge of central dopamine involvement in pair bond formation, expression, and maintenance. We first describe the neuroanatomical substrate within which dopamine exerts its effects on social bonding. We then describe dopamine receptor subtype-specific influences on pair bonding and how dopamine receptor activation may interact with activation of other neurochemical systems. Finally, we describe possible interactions between social bonding and substance abuse.

Neutron drip line in odd and even mass calcium and nickel nuclei

Neutron-rich Ca and Ni nuclei have been studied in a spherical relativistic mean-field formalism in coordinate space. A \ensuremath{\delta} interaction has been adopted to treat the pairing correlations for the neutrons. Odd nuclei have been treated in the blocking approximation. The effect of the positive-energy continuum and the role of pairing in the stability of nuclei have been investigated by use of the resonant-BCS approach. In Ca isotopes, $N=50$ is no longer a magic number, whereas in Ni nuclei, a new magic number emerges at $N=70$. There is a remarkable difference in the relative positions of the drip lines for odd and even isotopes. In Ca isotopes, the last bound even and odd nuclei are found to be $^{72}\mathrm{Ca}$ and $^{59}\mathrm{Ca}$, respectively. In Ni isotopes, the corresponding nuclei are $^{98}\mathrm{Ni}$ and $^{97}\mathrm{Ni}$, respectively. The origin of this difference in relative positions of the drip line in even and odd isotopes in the two chains is traced to the difference in the single-particle level structures and consequent modification in the magic numbers in the two elements. Pairing interaction is seen to play a major role. The effect of the width of the resonance states on pairing has also been investigated.

Efficient Calculation of Many Stacking and Pairing Free Energies in DNA from a Few Molecular Dynamics Simulations

Through the use of the one-step perturbation approach, 130 free energies of base stacking and 1024 free energies of base pairing in DNA have been calculated from only five simulations of a nonphysical reference state. From analysis of a diverse set of 23 natural and unnatural bases, it appears that stacking free energies and stacking conformations play an important role in pairing of DNA nucleotides. On the one hand, favourable pairing free energies were found for bases that do not have the possibility to form canonical hydrogen bonds, while on the other hand, good hydrogen-bonding possibilities do not guarantee a favourable pairing free energy if the stacking of the bases dictates an unfavourable conformation. In this application, the one-step perturbation approach yields a wealth of both energetic and structural information at minimal computational cost.