Laser-heated capillary discharge plasma waveguides for electron acceleration to 8 GeV

A plasma channel created by the combination of a capillary discharge and inverse Bremsstrahlung laser heating enabled the generation of electron bunches with energy up to 7.8 GeV in a laser-driven plasma accelerator. The capillary discharge created an initial plasma channel and was used to tune the plasma temperature, which optimized laser heating. Although optimized colder initial plasma temperatures reduced the ionization degree, subsequent ionization from the heater pulse created a fully ionized plasma on-axis. The heater pulse duration was chosen to be longer than the hydrodynamic timescale of ≈ 1 ns, such that later temporal slices were more efficiently guided by the channel created by the front of the pulse. Simulations are presented which show that this thermal self-guiding of the heater pulse enabled channel formation over 20 cm. The post-heated channel had lower on-axis density and increased focusing strength compared to relying on the discharge alone, which allowed for guiding of relativistically intense laser pulses with a peak power of 0.85 PW and wakefield acceleration over 15 diffraction lengths. Electrons were injected into the wake in multiple buckets and times, leading to several electron bunches with different peak energies. To create single electron bunches with low energy spread, experiments using localized ionization injection inside a capillary discharge waveguide were performed. A single injected bunch with energy 1.6 GeV, charge 38 pC, divergence 1 mrad, and relative energy spread below 2% full-width half-maximum was produced in a 3.3 cm-long capillary discharge waveguide. This development shows promise for mitigation of energy spread and future high efficiency staged acceleration experiments

Real-time correlators in warped AdS/CFT correspondence

We study real-time correlators in the warped AdS/CFT correspondence. We apply the prescription used in the usual AdS/CFT correspondence and obtain the retarded Green's functions for the scalar and vector fields in the spacelike warped and the null warped black hole backgrounds. We find that the retarded Green's functions and the cross sections are well consistent with the predictions from dual CFT. Our results not only support strongly the conjectured warped AdS/CFT correspondence, but also show that the usual relativistic AdS/CFT prescription of obtaining the real-time correlators remain effective in more general backgrounds with anisotropic conformal infinity.Comment: 27 page

Dipole Coupling Effect of Holographic Fermion in the Background of Charged Gauss-Bonnet AdS Black Hole

We investigate the holographic fermions in the charged Gauss-Bonnet $AdS_{d}$ black hole background with the dipole coupling between fermion and gauge field in the bulk. We show that in addition to the strength of the dipole coupling, the spacetime dimension and the higher curvature correction in the gravity background also influence the onset of the Fermi gap and the gap distance. We find that the higher curvature effect modifies the fermion spectral density and influences the value of the Fermi momentum for the appearance of the Fermi surface. There are richer physics in the boundary fermion system due to the modification in the bulk gravity.Comment: 16 pages, accepted for publication in JHE

Holographic Correlation Functions for Open Strings and Branes

In this paper, we compute holographically the two-point and three-point functions of giant gravitons with open strings. We consider the maximal giant graviton in $S^5$ and the string configurations corresponding to the ground states of Z=0 and Y=0 open spin chain, and the spinning string in AdS$_5$ corresponding to the derivative type impurities in Y=0 or Z=0 open spin chain as well. We treat the D-brane and open string contribution separately and find the corresponding D3-brane and string configurations in bulk which connect the composite operators at the AdS$_5$ boundary. We apply a new prescription to treat the string state contribution and find agreements for the two-point functions. For the three-point functions of two giant gravitons with open strings and one certain half-BPS chiral primary operator, we find that the D-brane contributions to structure constant are always vanishing and the open string contribution for the Y=0 ground state is in perfect match with the prediction in the free field limit.Comment: 25 page

Analytical study on holographic superconductors in external magnetic field

We investigate the holographic superconductors immersed in an external magnetic field by using the analytical approach. We obtain the spatially dependent condensate solutions in the presence of the magnetism and find analytically that the upper critical magnetic field satisfies the relation given in the Ginzburg-Landau theory. We observe analytically the reminiscent of the Meissner effect where the magnetic field expels the condensate. Extending to the D-dimensional Gauss-Bonnet AdS black holes, we examine the influence given by the Gauss-Bonnet coupling on the condensation. Different from the positive coupling, we find that the negative Gauss-Bonnet coupling enhances the condensation when the external magnetism is not strong enough.Comment: revised version, to appear in JHE

Aesthetic Procedures and Psychological Wellbeing in Saudi College Students: An In-Depth Exploration

Nouf F Bin Rubaian,1 Abdelaziz M Elfaki,2 Serene R Almuhaidib,3 Fajar A Aldulijan,4 Raghda S Qasim,3 Khalid Nabil Nagshabandi,5 Heba Yousef Al-Ojail,6 Shayma S Alsubaie7 1Department of Dermatology, King Fahad University Hospital, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia; 2Healing Icon Center, Al Khobar, Saudi Arabia; 3Department of Dermatology, Dammam Medical Complex, Dammam, Saudi Arabia; 4Department of Family Medicine, Johns Hopkins Aramco Healthcare, Dhahran, Eastern Province, Saudi Arabia; 5Department of Dermatology, College of Medicine, King Saud University Medical City (KSUMC), Riyadh, Saudi Arabia; 6Department of Dermatology, King Faisal University, Al Ahsa, Saudi Arabia; 7King Fahad University of Petroleum and Mineral, Interdisciplinary Research Center for Finance and Digital Economy, Dhahran, Saudi ArabiaCorrespondence: Serene R Almuhaidib, Department of Dermatology, Dammam Medical Complex, Dammam, Saudi Arabia, Email [email protected]: Minimally invasive aesthetic procedures are widely popular among the youth. Despite their prevalence, there is a significant gap in the research concerning the relationship between these procedures and psychological wellbeing, as well as an insufficient exploration of the barriers and motivators influencing their adoption, this study aims to address these gaps.Methods: This cross-sectional study has utilized a secure online survey directed at Saudi university students as the target population. The survey was consisting of 18-item electronic questionnaire including of 4 parts (demographical data, history of psychological illness and screening of current psychological wellbeing using WHO-5 well-being tool, history of doing cosmetic procedure, or willingness to do in the future, barriers and motivators to do cosmetic procedures), and it was distributed across multiple social media platforms.Results: A total of 8443 college students completed the study questionnaire. Exactly 1096 (13%) of the students underwent a cosmetic procedure. The most reported procedures were laser hair removal (9.1%), filler (5.3%), skin boosters (2.8%), and Botulinum toxin A injections (Botox) (2.6%). The most ranked motivators were being painless, with no side effects (8.8 out of 10), followed by being free (8.0 out of 10) and enhancing self-confidence (7.4 out of 10).Conclusion: No significant difference recorded at the overall psychological well-being score between who underwent cosmetic procedures and who did not.Keywords: aesthetic procedures, cosmetic dermatology, cosmetic dermatologic procedures, psychological wellbeing, mental health, college students, Saudi Arabi

Analytical study on holographic superconductors with backreactions

We employ the variational method for the Sturm-Liouville eigenvalue problem to analytically investigate the properties of the holographic superconductors. We find that the analytic method is still powerful when the backreaction is turned on. Reducing step size in the iterative procedure, we observe that the consistency of results between the analytic and numerical computations can be further improved. The obtained analytic result can be used to back up the numerical computations in the holographic superconductor in the fully backreacted spacetime.Comment: 10 pages, accepted by JHE

Genetic Basis of Growth Adaptation of Escherichia coli after Deletion of pgi, a Major Metabolic Gene

Bacterial survival requires adaptation to different environmental perturbations such as exposure to antibiotics, changes in temperature or oxygen levels, DNA damage, and alternative nutrient sources. During adaptation, bacteria often develop beneficial mutations that confer increased fitness in the new environment. Adaptation to the loss of a major non-essential gene product that cripples growth, however, has not been studied at the whole-genome level. We investigated the ability of Escherichia coli K-12 MG1655 to overcome the loss of phosphoglucose isomerase (pgi) by adaptively evolving ten replicates of E. coli lacking pgi for 50 days in glucose M9 minimal medium and by characterizing endpoint clones through whole-genome re-sequencing and phenotype profiling. We found that 1) the growth rates for all ten endpoint clones increased approximately 3-fold over the 50-day period; 2) two to five mutations arose during adaptation, most frequently in the NADH/NADPH transhydrogenases udhA and pntAB and in the stress-associated sigma factor rpoS; and 3) despite similar growth rates, at least three distinct endpoint phenotypes developed as defined by different rates of acetate and formate secretion. These results demonstrate that E. coli can adapt to the loss of a major metabolic gene product with only a handful of mutations and that adaptation can result in multiple, alternative phenotypes