Scale Invariance and the AdS/CFT Correspondence

Using the AdS/CFT correspondence, we show that the Anti-de Sitter (AdS) rotating (Kerr) black holes in five and seven dimensions provide us with examples of non-trivial field theories which are scale, but not conformally invariant. This is demonstrated by our computation of the actions and the stress-energy tensors of the four and six dimensional field theories residing on the boundary of these Kerr-AdS black holes spacetimes.Comment: 3 pages. LaTeX, IJMP style. Contribution to proceedings of DPF 2000, held at Ohio State

Measurements of interactions between acoustic fields and nonuniform mean flow

Two problems crucial to the stability of longitudinal acoustic waves in solid rocket motors are examined experimentally. The first is the dissipation of energy associated with an average flow inward at the lateral boundary. Measurements reported here, though subject to considerable experimental error, show that the actual losses are much larger than predicted by the approximate one dimensional analysis. The second problem is the attenuation of waves accompanying reflection by the nonuniform flow in a choked exhaust nozzle. Empahsis in this work has been on technique, to provide data relatively easily and inexpensively. It appears that good results can be obtained in a routine manner using small supersonic wind tunnel operated as an open cycle. At least for Mach numbers up to 0.04 at the nozzle entrance, difficulties with signal/noise are satisfactorily overcome with a tracking filter

Intestinal epithelial responses to Salmonella enterica serovar Enteritidis: Effects on intestinal permeability and ion transport

Salmonella infection of chickens that leads to potential human foodborne salmonellosis continues to be a major concern. Chickens serve as carriers but, in contrast to humans, rarely show any clinical signs including diarrhea. The present investigations aimed to elucidate whether the absence of diarrhea during acute Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) infection may be linked to specific changes in the electrophysiological properties of the chicken gut. Immediately after slaughter, intestinal pieces of the mid-jejunum and cecum of either commercial broiler or specific pathogen-free (SPF) chickens were mounted in Ussing chambers in 2 separate experimental series. Living Salmonella Enteritidis (3 × 109) or Salmonella Enteritidis endotoxin (20 mg/L), or both, were added to the mucosal side for 1 h. In both experimental series, the Salmonella infection decreased the trans-epithelial ion conductance Gt (P < 0.05). In the jejunum of SPF chickens, there was also a marked decrease in net charge transfer across the epithelium, evidenced by decreased short-circuit current (Isc, P < 0.05). Interestingly, the mucosal application of Salmonella endotoxin to the epithelial preparations from jejunum and cecum of SPF chicken had an effect similar to living bacteria. However, the endotoxin had no additional effect on the intestinal function in the presence of bacteria. The decreasing effect of Salmonella and or its endotoxin on Gt could be partly reversed by serosal addition of histamine. To our knowledge, this is the first study to address the functional response of native intestinal epithelium of chicken to an in vitro Salmonella infection. For the first time, it can be reported that intestinal ion permeability of chicken decreases acutely by the presence of Salmonella. This type of response could counteract ion and fluid secretion and may thus, at least in part, explain why chickens do not develop overt diarrhea after Salmonella infection

Implications of AI Chatbots in Education: Challenges and Solution

AI Chatbots are commonly used nowadays in different sectors such as real estate, marketing, healthcare, as well as education, in which both students and educators use these intelligent systems to gain personalized support and guidance to perform their tasks. Usage varies from solving assignments or setting the assignment questions, similarly, matters arising on whether these uses are acceptable, salutary, or ethical. In this research, a review of AI chatbots, and their ethical implications are presented, and a framework for better use of AI Chatbots in Educational Institutions is proposed in order to control the unethical use of it

Exosuit-induced improvements in walking after stroke: comprehensive analysis on gait energetics and biomechanics

Outstanding Poster Presentation Finalis

Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke

Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance—walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint powers, and metabolic power. Compared to walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R2= 0.83, P= 0.004) and nonparetic (R2= 0.73, P= 0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in nonparetic limb COM power (R2= 0.80, P= 0.007), not paretic limb COM power (P> 0.05). These findings provide a fundamental understanding of how individuals poststroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking.Accepted manuscript2019-03-0

Campylobacter jejuni colonization promotes the translocation of Escherichia coli to extra-intestinal organs and disturbs the short-chain fatty acids profiles in the chicken gut

For a long time Campylobacter was only considered as a commensal microorganism in avian hosts restricted to the ceca, without any pathogenic features. The precise reasons for the symptomless chicken carriers are still unknown, but investigations of the gastrointestinal ecology of broiler chickens may improve our understanding of the microbial interactions with the host. Therefore, the current studies were conducted to investigate the effects of Campylobacter jejuni colonization on Escherichia coli translocation and on the metabolic end products (short-chain fatty acids, SCFAs). Following oral infection of 14 day old broiler chickens with 1 × 108 CFU of Campylobacter jejuni NCTC 12744 in two independent animal trials, it was found that C. jejuni heavily colonized the intestine and disseminate to extra-intestinal organs. Moreover, in both animal trials, the findings revealed that C. jejuni promoted the translocation of E. coli with a higher number encountered in the spleen and liver at 14 days post infection (dpi). In addition, Campylobacter affected the microbial fermentation in the gastrointestinal tract of broilers by reducing the amount of propionate, isovalerate, and isobutyrate in the cecal digesta of the infected birds at 2 dpi and, at 7 and 14 dpi, butyrate, isobutyrate, and isovalerate were also decreased. However, in the jejunum, the C. jejuni infection lowered only butyrate concentrations at 14 dpi. These data indicated that C. jejuni may utilize SCFAs as carbon sources to promote its colonization in the chicken gut, suggesting that Campylobacter cannot only alter gut colonization dynamics but might also influence physiological processes due to altered microbial metabolite profiles. Finally, the results demonstrated that C. jejuni can cross the intestinal epithelial barrier and facilitates the translocation of Campylobacter itself as well as of other enteric microorganisms such as E. coli to extra-intestinal organs of infected birds. Altogether, our findings suggest that the Campylobacter carrier state in chicken is characterised by multiple changes in the intestinal barrier function, which supports multiplication and survival within the host

Scale without Conformal Invariance at Three Loops

We carry out a three-loop computation that establishes the existence of scale without conformal invariance in dimensional regularization with the MS scheme in d=4-epsilon spacetime dimensions. We also comment on the effects of scheme changes in theories with many couplings, as well as in theories that live on non-conformal scale-invariant renormalization group trajectories. Stability properties of such trajectories are analyzed, revealing both attractive and repulsive directions in a specific example. We explain how our results are in accord with those of Jack & Osborn on a c-theorem in d=4 (and d=4-epsilon) dimensions. Finally, we point out that limit cycles with turning points are unlike limit cycles with continuous scale invariance.Comment: 21 pages, 3 figures, Erratum adde