Non-resonant direct p- and d-wave neutron capture by 12C

Discrete gamma-rays from the neutron capture state of 13C to its low-lying bound states have been measured using pulsed neutrons at En = 550 keV. The partial capture cross sections have been determined to be 1.7+/-0.5, 24.2+/-1.0, 2.0+/-0.4 and 1.0+/-0.4 microb for the ground (1/2-), first (1/2+), second (3/2-) and third (5/2+) excited states, respectively. From a comparison with theoretical predictions based on the non-resonant direct radiative capture mechanism, we could determine the spectroscopic factor for the 1/2+ state to be 0.80 +/- 0.04, free from neutron-nucleus interaction ambiguities in the continuum. In addition we have detected the contribution of the non-resonant d-wave capture component in the partial cross sections for transitions leading to the 1/2- and 3/2- states. While the s-wave capture dominates at En < 100 keV, the d-wave component turns out to be very important at higher energies. From the present investigation the 12C(n,gamma)13C reaction rate is obtained for temperatures in the range 10E+7 - 10E+10 K.Comment: Accepted for publication in Phys. Rev. C. - 16 pages + 8 figure

p63 is an alternative p53 repressor in melanoma that confers chemoresistance and a poor prognosis.

The role of apoptosis in melanoma pathogenesis and chemoresistance is poorly characterized. Mutations in TP53 occur infrequently, yet the TP53 apoptotic pathway is often abrogated. This may result from alterations in TP53 family members, including the TP53 homologue TP63. Here we demonstrate that TP63 has an antiapoptotic role in melanoma and is responsible for mediating chemoresistance. Although p63 was not expressed in primary melanocytes, up-regulation of p63 mRNA and protein was observed in melanoma cell lines and clinical samples, providing the first evidence of significant p63 expression in this lineage. Upon genotoxic stress, endogenous p63 isoforms were stabilized in both nuclear and mitochondrial subcellular compartments. Our data provide evidence of a physiological interaction between p63 with p53 whereby translocation of p63 to the mitochondria occurred through a codependent process with p53, whereas accumulation of p53 in the nucleus was prevented by p63. Using RNA interference technology, both isoforms of p63 (TA and ΔNp63) were demonstrated to confer chemoresistance, revealing a novel oncogenic role for p63 in melanoma cells. Furthermore, expression of p63 in both primary and metastatic melanoma clinical samples significantly correlated with melanoma-specific deaths in these patients. Ultimately, these observations provide a possible explanation for abrogation of the p53-mediated apoptotic pathway in melanoma, implicating novel approaches aimed at sensitizing melanoma to therapeutic agents

Regeneration versus scarring in vertebrate appendages and heart

Injuries to complex human organs, such as the limbs and the heart, result in pathological conditions, for which we often lack adequate treatments. While modern regenerative approaches are based on the transplantation of stem cell-derived cells, natural regeneration in lower vertebrates, such as zebrafish and newts, relies predominantly on the intrinsic plasticity of mature tissues. This property involves local activation of the remaining material at the site of injury to promote cell division, cell migration and complete reproduction of the missing structure. It remains an unresolved question why adult mammals are not equally competent to reactivate morphogenetic programmes. Although organ regeneration depends strongly on the proliferative properties of cells in the injured tissue, it is apparent that various organismic factors, such as innervation, vascularization, hormones, metabolism and the immune system, can affect this process. Here, we focus on a correlation between the regenerative capacity and cellular specialization in the context of functional demands, as illustrated by appendages and heart in diverse vertebrates. Elucidation of the differences between homologous regenerative and non-regenerative tissues from various animal models is essential for understanding the applicability of lessons learned from the study of regenerative biology to clinical strategies for the treatment of injured human organs

A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

Coordinated generation of multiple ocular-like cell lineages and fabrication of functional corneal epithelial cell sheets from human iPS cells

We describe a protocol for the generation of a functional and transplantable corneal epithelium derived from human induced pluripotent stem (iPS) cells. When this protocol is followed, a proportion of iPS cells spontaneously form circular colonies, each of which is composed of four concentric zones. Cells in these zones have different morphologies and immunostaining characteristics, resembling neuroectoderm, neural crest, ocular-surface ectoderm, or surface ectoderm. We have named this 2D colony a 'SEAM' (self-formed ectodermal autonomous multizone), and previously demonstrated that cells within the SEAM have the potential to give rise to anlages of different ocular lineages, including retinal cells, lens cells, and ocular-surface ectoderm. To investigate the translational potential of the SEAM, cells within it that resemble ocular-surface epithelia can be isolated by pipetting and FACS sorting into a population of corneal epithelial-like progenitor cells. These can be expanded and differentiated to form an epithelial layer expressing K12 and PAX6, and able to recover function in an animal model of corneal epithelial dysfunction after surgical transplantation. The whole protocol, encompassing human iPS cell preparation, autonomous differentiation, purification, and subsequent differentiation, takes between 100 and 120 d, and is of potential use to researchers with an interest in eye development and/or ocular-surface regeneration. Experience with human iPS cell culture and sorting via FACS will be of benefit for researchers performing this protocol

Ytterbium nuclear-spin qubits in an optical tweezer array

We report on the realization of a fast, scalable, and high-fidelity qubit architecture, based on $^{171}$Yb atoms in an optical tweezer array. We demonstrate several attractive properties of this atom for its use as a building block of a quantum information processing platform. Its nuclear spin of 1/2 serves as a long-lived and coherent two-level system, while its rich, alkaline-earth-like electronic structure allows for low-entropy preparation, fast qubit control, and high-fidelity readout. We present a near-deterministic loading protocol, which allows us to fill a 10$\times$10 tweezer array with 92.73(8)% efficiency and a single tweezer with 96.0(1.4)% efficiency. In the future, this loading protocol will enable efficient and uniform loading of target arrays with high probability, an essential step in quantum simulation and information applications. Employing a robust optical approach, we perform submicrosecond qubit rotations and characterize their fidelity through randomized benchmarking, yielding 5.2(5)$\times 10^{-3}$ error per Clifford gate. For quantum memory applications, we measure the coherence of our qubits with $T_2^*$=3.7(4) s and $T_2$=7.9(4) s, many orders of magnitude longer than our qubit rotation pulses. We measure spin depolarization times on the order of tens of seconds and find that this can be increased to the 100 s scale through the application of a several-gauss magnetic field. Finally, we use 3D Raman-sideband cooling to bring the atoms near their motional ground state, which will be central to future implementations of two-qubit gates that benefit from low motional entropy.Comment: Fixed typos, refined scattering model, adds T1 dat

Passive maternal antibody transfer to eggs and larvae of tiger grouper (Epinephelus fuscoguttatus)

The immune response of Tiger grouper (E. fuscoguttatus) broodstocks and its passive transfer of maternal antibodies to eggs and larvae were evaluated following vaccination with an inactivated V.harveyi. Tiger grouper broodstock (mean BW 8.66 ± 0.09 kg, n=19) were vaccinated intraperitoneally (IP) and followed by a booster two weeks post vaccination, while Controlled Non-vaccinated (CG) broodstock were IP injected with PBS. The serum antibody level against V.harveyi was monitored for two weeks on post-vaccination and monthly up to 5 months post-vaccination. This study showed that the Vaccinated Group (VG) broodstock induced significantly (P<0.05) higher in specific IgM antibody level against V.harveyi as compared to the CG, which in turn induced a marked increased (P<0.05) in specific IgM in eggs and larvae produced from VG broodstock at 14 weeks post vaccination. The findings from this study suggested that inactivated V.harveyi vaccines were able to stimulate the immune response in broodstock and passively transferred the maternal antibody to their eggs and larvae

Bifurcation of internally heated flow in a vertical pipe

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The development of fluid motion in an infinitely long circular pipe with homogeneously distributed internal heat source is examined numerically. The pipe is placed vertically in the gravity field with the pipe wall temperature being kept constant. The motion of the fluid is driven upward by the buoyancy force as well as downward by an applied pressure gradient along the pipe axis. Thus, the basic velocity profile can become inflectional and we may anticipate that the flow may become unstable in contrast to the isothermal pipe flow which is known to be linearly stable for any Reynolds number. We find that the linear instabilities always occur within the region where the basic velocity profile is inflectional but not totally reverse. Our nonlinear analysis indicates that there are two types of nonlinear solutions, referred to as spirals and ribbons. They bifurcate simultaneously from the same point on the neutral curve. Furthermore, the branch of the ribbon extends far inside the region where the basic state is linearly stable and reaches the isothermal limit, creating a nonlinear solution in ’pure’ pipe flow for the case with Pr = 0. For the case with Pr = 7 nonlinear interactions between spirals with different azimuthal wavenumbers are observed.dc201

Role of Hepatic Stellate Cells in the Early Phase of Liver Regeneration in Rat: Formation of Tight Adhesion to Parenchymal Cells

We investigated activation mechanisms of hepatic stellate cells (HSCs) that are known to play pivotal roles in the regeneration process after 70% partial hepatectomy (PHx). Parenchymal liver cells (PLCs) and non-parenchymal cells (NPLCs) were isolated and purified from the regenerating livers at 1, 3, 7, 14 days after PHx. Each liver cell fraction was stained by immunocytochemistry using an anti-desmin antibody as a marker for HSCs, anti-alpha-smooth muscle actin (alpha-SMA) as a marker for activated HSCs, and 5-bromo-2'-deoxyuridine (BrdU) for detection of proliferating cells. Tissue sections from regenerating livers were also analyzed by immunohistochemistry and compared with the results obtained for isolated cell fractions. One and 3 days after PHx, PLC-enriched fraction contained HSCs adhered to PLCs. The HSCs adhered to PLCs were double positive for BrdU and alpha-SMA, and formed clusters suggesting that these HSCs were activated. However, HSC-enriched fraction contained HSCs not adhered PLCs showed positive staining for anti-desmin antibody but negative for anti-alpha-SMA antibody. These results suggest that HSCs are activated by adhering to PLCs during the early phase of hepatic regeneration