Quantum Magnetism of Spin-Ladder Compounds with Trapped-Ion Crystals

The quest for experimental platforms that allow for the exploration, and even control, of the interplay of low dimensionality and frustration is a fundamental challenge in several fields of quantum many-body physics, such as quantum magnetism. Here, we propose the use of cold crystals of trapped ions to study a variety of frustrated quantum spin ladders. By optimizing the trap geometry, we show how to tailor the low dimensionality of the models by changing the number of legs of the ladders. Combined with a method for selectively hiding of ions provided by laser addressing, it becomes possible to synthesize stripes of both triangular and Kagome lattices. Besides, the degree of frustration of the phonon-mediated spin interactions can be controlled by shaping the trap frequencies. We support our theoretical considerations by initial experiments with planar ion crystals, where a high and tunable anisotropy of the radial trap frequencies is demonstrated. We take into account an extensive list of possible error sources under typical experimental conditions, and describe explicit regimes that guarantee the validity of our scheme

Dynamic morphology of sutureless cataract wounds--effect of incision angle and location.

ObjectiveSutureless cataract surgery has been growing in popularity over the last decade. These clear corneal incisions allow for rapid visual recovery after phacoemulsification, but may be associated with an increased risk of endophthalmitis. The purpose of this study was to evaluate the effect of intraocular pressure (IOP), location, and angle of cataract incisions on wound apposition and sealing in postmortem globes.MethodsThis was an ex vivo laboratory investigation of 20 rabbit eyes and 14 human eyes. Self-sealing clear corneal, limbal, and scleral incisions were created and IOP was controlled with an infusion cannula. Incisions were made at a variety of angles. Optical coherence tomography was used to image the incisions in real time as the IOP was varied by raising and lowering the infusion bottle, so as to simulate the variation in IOP occurring with blinking or squeezing of the eye.ResultsWith each type of incision, optical coherence tomography demonstrated the dynamic nature of cataract wound morphology as IOP was varied. Higher IOPs, in general, were associated with more tightly sealed wounds than lower IOPs, but this varied according to the location and angle of the incisions. More perpendicular incisions, relative to the surface tangent, sealed less well than incisions created at smaller angles at higher levels of IOP; At lower IOPs, the reverse relationship was observed such that more perpendicular incisions sealed less well than smaller incision angles.ConclusionChanges in IOP may result in variable and sometime poor wound apposition in sutureless cataract incisions. The type of incision and angle of the incision may affect the likelihood of inoculation of the aqueous humor with potentially pathogenic bacteria. For each type of incision, there may be a critical angle at which the incision is better able to withstand fluctuations in IOP

Dynamic morphology of sutureless cataract wounds--effect of incision angle and location.

ObjectiveSutureless cataract surgery has been growing in popularity over the last decade. These clear corneal incisions allow for rapid visual recovery after phacoemulsification, but may be associated with an increased risk of endophthalmitis. The purpose of this study was to evaluate the effect of intraocular pressure (IOP), location, and angle of cataract incisions on wound apposition and sealing in postmortem globes.MethodsThis was an ex vivo laboratory investigation of 20 rabbit eyes and 14 human eyes. Self-sealing clear corneal, limbal, and scleral incisions were created and IOP was controlled with an infusion cannula. Incisions were made at a variety of angles. Optical coherence tomography was used to image the incisions in real time as the IOP was varied by raising and lowering the infusion bottle, so as to simulate the variation in IOP occurring with blinking or squeezing of the eye.ResultsWith each type of incision, optical coherence tomography demonstrated the dynamic nature of cataract wound morphology as IOP was varied. Higher IOPs, in general, were associated with more tightly sealed wounds than lower IOPs, but this varied according to the location and angle of the incisions. More perpendicular incisions, relative to the surface tangent, sealed less well than incisions created at smaller angles at higher levels of IOP; At lower IOPs, the reverse relationship was observed such that more perpendicular incisions sealed less well than smaller incision angles.ConclusionChanges in IOP may result in variable and sometime poor wound apposition in sutureless cataract incisions. The type of incision and angle of the incision may affect the likelihood of inoculation of the aqueous humor with potentially pathogenic bacteria. For each type of incision, there may be a critical angle at which the incision is better able to withstand fluctuations in IOP

Phenotypic manifestations of inflammatory bowel disease differ between Hispanics and non-Hispanic whites: results of a large cohort study

Hispanics are the fastest growing minority in the United States, yet few studies have examined the phenotypes of inflammatory bowel disease (IBD) in this population. No studies compare IBD presentation between foreign and US-born Hispanics. Our aim was to compare phenotypic characteristics of IBD between Hispanics and non-Hispanic Whites (NHWs), as well as between US-born and foreign-born Hispanics. We retrospectively identified cohorts of adult IBD patients from 1998 to 2009 and compared ethnic variation in phenotype, including disease type (Crohn's disease or ulcerative colitis (UC)), extra-intestinal manifestations (EIMs), Montreal classification, surgeries, hospitalizations, and medication prescription. A total of 325 patients were included; 208 were Hispanics. Foreign-born Hispanics, accounting for 68% of the total, were diagnosed at an older age than US-born Hispanics and NHWs (45 vs. 25 and 27, respectively, P<0.05). Foreign-born Hispanics manifested more UC than US-born Hispanics or NHWs (59.9% vs. 41% and 28.2%, respectively, P<0.05). No difference was noted in the prevalence of EIMs between Hispanics and NHWs. More upper gastrointestinal tract Crohn's was observed in NHWs (12.5% vs. 3.9%, P<0.05). The incidence density rate of IBD-related surgeries in NHWs was higher than in Hispanics (22.9 vs. 7.3 surgeries/100 person-years, P<0.01, hazard ratio: 0.3, 95% confidence interval: 0.14-0.5). Hispanic patients had fewer prescriptions for biologics and immunomodulators than NHWs (22.2% vs. 55.6%, P<0.01 and 35.7% vs. 53.8%, P<0.01, respectively). This study demonstrates differences in IBD presentation among NHW, US-born Hispanic, and foreign-born Hispanic groups. Further investigation to identify environmental and genetic differences between ethnic groups affected by IBD is warranted

Flow diversion for the treatment of posterior inferior cerebellar artery aneurysms: a novel classification and strategies

BACKGROUND: The pipeline embolization device (PED) is frequently used in the treatment of anterior circulation aneurysms, especially around the carotid siphon, with generally excellent results. However, treatment of posterior inferior cerebellar artery (PICA) aneurysms with flow diversion (FD) has not been specifically described or discussed. While there are reports of treating PICA aneurysms using placement of FD stents in the vertebral artery, there are no reports of treating these lesions by placement of flow diverting stents in the PICA vessel itself. Due to the unique anatomy and morphology of these aneurysms, it requires special attention. We assessed our multi-institutional experience treating these lesions, including the first reported cases of the PED placed within the PICA. METHODS: Institutional databases of neuroendovascular procedures were reviewed for cases of intracranial aneurysms treated with the PED. Patient and aneurysm data as well as angiographic imaging were reviewed for all cases of PICA aneurysms treated with the PED. PICA aneurysms were defined as aneurysms that involved the PICA. Vertebral aneurysms without disease in the PICA were excluded from the study. RESULTS: 10 PICA aneurysms were treated during the study period. These were classified based on their morphology and location into two main types and five total subtypes for consideration of treatment with flow diversion. All aneurysms were successfully treated, with 8/10 completely obliterated and 2 with a partial reduction in size. Three patients had the PED placed entirely in the PICA and no patient suffered from a medullary or cerebellar stroke. All PEDs were patent and all patients were independent at the last follow-up. CONCLUSIONS: The PED may be used successfully to treat select aneurysms of the PICA. We present the first described cases of successful PED treatment of PICA aneurysms with direct placement of the PED in the PICA vessel itself. The proposed classification system aids in that selection