27,218 research outputs found
The Nelson-Seiberg theorem revised
The well-accepted Nelson-Seiberg theorem relates R-symmetries to
supersymmetry (SUSY) breaking vacua, and provides a guideline for SUSY model
building which is the most promising physics beyond the Standard Model. In the
case of Wess-Zumino models with perturbative superpotentials, we revise the
theorem to a combined necessary and sufficient condition for SUSY breaking
which can be easily checked before solving the vacuum. The revised theorem
provides a powerful tool to construct either SUSY breaking or SUSY vacua, and
offers many practicable applications in low energy SUSY model building and
string phenomenology.Comment: 5 pages; v2: abstract and introduction revised; v3: condition of
perturbative superpotentials added, JHEP published versio
Non-adiabatic holonomic quantum computation in linear system-bath coupling
Non-adiabatic holonomic quantum computation in decoherence-free subspaces
protects quantum information from control imprecisions and decoherence. For the
non-collective decoherence that each qubit has its own bath, we show the
implementations of two non-commutable holonomic single-qubit gates and one
holonomic nontrivial two-qubit gate that compose a universal set of
non-adiabatic holonomic quantum gates in decoherence-free-subspaces of the
decoupling group, with an encoding rate of . The proposed scheme
is robust against control imprecisions and the non-collective decoherence, and
its non-adiabatic property ensures less operation time. We demonstrate that our
proposed scheme can be realized by utilizing only two-qubit interactions rather
than many-qubit interactions. Our results reduce the complexity of practical
implementation of holonomic quantum computation in experiments. We also discuss
the physical implementation of our scheme in coupled microcavities.Comment: 2 figures; accepted by Sci. Re
Mechanical rolling formation of interpenetrated lithium metal/lithium tin alloy foil for ultrahigh-rate battery anode
To achieve good rate capability of lithium metal anodes for high-energy-density batteries, one fundamental challenge is the slow lithium diffusion at the interface. Here we report an interpenetrated, three-dimensional lithium metal/lithium tin alloy nanocomposite foil realized by a simple calendering and folding process of lithium and tin foils, and spontaneous alloying reactions. The strong affinity between the metallic lithium and lithium tin alloy as mixed electronic and ionic conducting networks, and their abundant interfaces enable ultrafast charger diffusion across the entire electrode. We demonstrate that a lithium/lithium tin alloy foil electrode sustains stable lithium stripping/plating under 30mAcm(-2) and 5mAhcm(-2) with a very low overpotential of 20mV for 200 cycles in a commercial carbonate electrolyte. Cycled under 6C (6.6mAcm(-2)), a 1.0mAhcm(-2) LiNi0.6Co0.2Mn0.2O2 electrode maintains a substantial 74% of its capacity by pairing with such anode
μ-Oxalato-bis[bis(2,2′-bipyridine)manganese(II)] bis(perchlorate) 2,2′-bipyridine solvate
The unit cell of the title compound, [Mn2(C2O4)(C10H8N2)4](ClO4)2·C10H8N2, consists of a binuclear cation, two perchlorate anions, and one solvent 2,2′-bipyridine (bpy) molecule. In the complex cation [Mn2(C2O4)(C10N2H8)4]2+, two MnII atoms are bridged by a bis(bidentate) oxalate ligand, each MnII atom being further coordinated by two bpy ligands in a distorted octahedral geometry. The distance between the two six-coordinated metal atoms is 5.583 (1) Å. π–π stacking interactions [interplanar distances between bpy rings = 3.739 (1) Å] are essential to the supramolecular assembly. There are extensive interionic C—H⋯O interactions between the cations and between the cation and anion. Three of the four perchlorate O atoms are disordered over two sets of sites with occupancy ratios of 0.852 (6):0.148 (6)
Circulating tissue factor-positive procoagulant microparticles in patients with type 1 diabetes
Aim: To investigate the count of circulating tissue factor-positive (TF+) procoagulant microparticles (MPs) in patients with type 1 diabetes mellitus (T1DM). Methods: This case-control study included patients with T1DM and age and sex-matched healthy volunteers. The counts of phosphatidylserine-positive (PS+) MPs and TF(+)PS(+)MPs and the subgroups derived from different cell types were measured in the peripheral blood sample of the two groups using multicolor flow cytometric assay. We compared the counts of each MP between groups as well as the ratio of the TF(+)PS(+)MPs and PS(+)MPs (TF(+)PS(+)MPs/PS(+)MPs). Results: We recruited 36 patients with T1DM and 36 matched healthy controls. Compared with healthy volunteers, PS(+)MPs, TF(+)PS(+)MPs and TF(+)PS(+)MPs/PS(+)MPs were elevated in patients with T1DM (PS(+)MPs: 1078.5 +/- 158.08 vs 686.84 +/- 122.04/mu L, P <0.001; TF(+)PS(+)MPs: 202.10 +/- 47.47 vs 108.33 +/- 29.42/mu L, P <0.001; and TF(+)PS(+)MPs/PS(+)MPs: 0.16 +/- 0.04 vs 0.19 +/- 0.05, P = 0.004), mostly derived from platelet, lymphocytes and endothelial cells. In the subgroup analysis, the counts of total and platelet TF(+)PS(+)MPs were increased in patients with diabetic retinopathy (DR) and with higher HbA1c, respectively. Conclusion: Circulating TF(+)PS(+)MPs and those derived from platelet, lymphocytes and endothelial cells were elevated in patients with T1DM.De tre första författarna delar förstaförfattarskapet.</p
Hexaaquacobalt(II) 3,3′-dicarboxybiphenyl-4,4′-dicarboxylate
In the crystal structure of the title compound, [Co(H2O)6](C16H8O8), both the cation and anion are centrosymmetric. The Co cation displays a CoO6 octahedral geometry formed by six water molecules. In the anion, the two carboxyl groups are oriented at dihedral angles of 4.8 (5) and 10.4 (7)° with respect to the benzene ring. Very strong O—H⋯O hydrogen bonds between the protonated and deprotonated carboxylate groups occur. Neighbouring cations and anions are connected through O—H⋯O hydrogen bonds into a three-dimensional supramolecular structure
Damaged DNA-binding protein 2 (DDB2) protects against UV irradiation in human cells and Drosophila
<p>Abstract</p> <p>Background</p> <p>We observed previously that cisplatin-resistant HeLa cells were cross-resistant to UV light due to accumulation of DDB2, a protein implicated in DNA repair. More recently, we found that cFLIP, which represents an anti-apoptotic protein whose level is induced by DDB2, was implicated in preventing apoptosis induced by death-receptor signaling. In the present study, we investigated whether DDB2 has a protective role against UV irradiation and whether cFLIP is also involved in this process.</p> <p>Methods</p> <p>We explored the role of DDB2 in mediating UV resistance in both human cells and Drosophila. To do so, DDB2 was overexpressed by using a full-length open reading frame cDNA. Conversely, DDB2 and cFLIP were suppressed by using antisense oligonucleotides. Cell survival was measured using a colony forming assay. Apoptosis was monitored by examination of nuclear morphology, as well as by flow cytometry and Western blot analyses. A transcription reporter assay was also used to assess transcription of cFLIP.</p> <p>Results</p> <p>We first observed that the cFLIP protein was upregulated in UV-resistant HeLa cells. In addition, the cFLIP protein could be induced by stable expression of DDB2 in these cells. Notably, the anti-apoptotic effect of DDB2 against UV irradiation was largely attenuated by knockdown of cFLIP with antisense oligonucleotides in HeLa cells. Moreover, overexpression of DDB2 did not protect against UV in VA13 and XP-A cell lines which both lack cFLIP. Interestingly, ectopic expression of human DDB2 in <it>Drosophila </it>dramatically inhibited UV-induced fly death compared to control GFP expression. On the other hand, expression of DDB2 failed to rescue a different type of apoptosis induced by the genes <it>Reaper </it>or <it>eiger</it>.</p> <p>Conclusion</p> <p>Our results show that DDB2 protects against UV stress in a cFLIP-dependent manner. In addition, the protective role of DDB2 against UV irradiation was found to be conserved in divergent living organisms such as human and <it>Drosophila</it>. In addition, UV irradiation may activate a cFLIP-regulated apoptotic pathway in certain cells.</p
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Transient flow analysis in a Roots blower: Experimental and numerical investigations
It is widely acknowledged that rotary positive displacement machines exhibit highly unsteady flow fields that affect their performance. The presence of the operational clearances impacts this unsteady flow field and further affects the performance. However, the exact nature of these unsteady flow mechanisms remains largely unknown that necessitates both detailed experimental investigations and computational modelling. Thus, the present study employs both optical visualization and unsteady Reynolds-Averaged Navier Stokes (URANS) computational modelling methods while focussing on investigating the transient flow field inside a Roots blower, a general type of the rotary positive displacement machine. Straight lobes in a Roots blower provide convenient optical access to experimentally analyse internal flow and compare it with the predictions obtained by standard computational models. In the first part of this paper, this study covers the low-speed experimental investigations using i) High-Speed Camera (HC), ii) the continuous High-Speed Particle Image Velocimetry (CPIV) and, iii) the instantaneous PIV (IPIV) obtained with a double pulse laser and a double shutter camera. Relative merits from these techniques are discussed with respect to the Roots blower unsteady flow mechanisms. In addition, computational analyses are performed using a combination of in-house and commercial modelling methods and the results are compared against the experiments. The results confirm the existence of highly three-dimensional and unsteady flow field where certain distinct flow mechanisms originating from the operational clearances impact the performance of the Roots blower. The study also highlights challenges of the experimental and computational methods used for evaluation of positive displacement machines that impact the accuracy of results
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