Weak Measurements in Nano-optics

Background: Weak measurement involves weak coupling between the system and the measuring device (pointer) enables large amplification and high precision measurement of small physical parameters. The outcome of this special measurement procedure involving nearly mutually orthogonal pre- and post-selection of states in such weakly interacting systems leads to weak value that can become exceedingly large and lie outside the eigenvalue spectrum of the measured observable. This unprecedented ability of weak value amplification of small physical parameters has been successfully exploited for various metrological applications in the optical domain and beyond. Even though it is a quantum mechanical concept, it can be understood using the classical electromagnetic theory of light and thus can be realized in classical optics. Objective: Here, we briefly review the basic concepts of weak measurement and weak value amplification, provide illustrative examples of its implementation in various optical domains. The applications involve measuring ultra-sensitive beam deflections, high precision measurements of angular rotation, phase shift, temporal shift, frequency shift and so forth, and expand this extraordinary concept in the domain of nano-optics and plasmonics. Methods: In order to perform weak value amplification, we have used Gaussian beam and spectral response as the pointer subsequently. The polarization state associated with the pointer is used as pre and post-selection device. Results: We reveal the weak value amplification of sub-wavelength optical effects namely the Goos-Hänchen shift and the spin hall shift. Further, we demonstrate weak measurements using spectral line shape of resonance as a natural pointer, enabling weak value amplification beyond the conventional limit, demonstrating natural weak value amplification in plasmonic Fano resonances and so forth. The discussed concepts could have useful implications in various nano-optical systems to amplify tiny signals or effects. Conclusion: The emerging prospects of weak value amplification towards the development of novel optical weak measurement devices for metrological applications are extensively discussed. </jats:sec

Overview of Corneal Transplantation for the Nonophthalmologist

Corneal transplant is a procedure that aims to replace dysfunctional corneal tissue with a transparent graft and is one of the most widely performed transplant surgeries, but its public and professional awareness is low outside of ophthalmology. Corneal tissue consists of 5 major layers that serve to maintain its structural integrity and refractive shape: the epithelium, Bowman’s layer, the stroma, Descemet’s membrane, and the endothelium. Failure or irreversible damage to any layer of the cornea may be an indication for corneal transplant, and variants of this procedure may be full thickness or selectively lamellar. Complications related to corneal transplantation may occur anywhere from during surgery to years afterward, including rejection, dehiscence, cataract, and glaucoma. Complications should be managed by an ophthalmologist, but other physicians should be aware of prophylactic medications. Topical immunosuppressants and steroids are effective for preventing and treating rejection episodes, whereas there is little evidence to support the use of systemic immunosuppression. Eye protection is recommended for any corneal transplant recipient. Physicians should counsel patients on corneal donation, especially if outside the United States, where donor tissue is in short supply

Effect of Arthrodesis of the First-Metatarsophalangeal Joint on the Alignment and Stability of the First-Tarsometatarsal Joint: A Large Sample-Sized Radiographic Study

Category: Midfoot/Forefoot; Bunion Introduction/Purpose: The hallux metatarsophalangeal (MTP) joint plays an important role in maintaining mobility of the first ray and arthrodesis of this joint is used to treat a variety of deformities. Intuitively, fusion of a joint may cause instability of an adjacent joint, however, recent studies have shown that hallux MTP arthrodesis in patients with hallux valgus can improve the stability of the first-tarsometatarsal (TMT) joint. The goal of this study was to investigate the impacts of hallux MTP arthrodesis on the alignment of the first TMT joint in a large sample-sized cohort. Methods: This was a retrospective study that included one group of patients without hallux valgus (Control Group ) and one group with hallux valgus deformity. Pre-operative and six-month post-operative weight-bearing radiographs were used to evaluate the alignment of the hallux and the first TMT joint. The parameters included the hallux valgus angle (HVA), 1-2 intermetatarsal angle (IMA), first metatarsal–medial cuneiform angle (1MCA), medial cuneiform–first metatarsal angle (MC1A), relative cuneiform slope (RCS), and distal medial cuneiform angle (DMCA). A paired t-test was used to study the impact of first MTP arthrodesis on the above parameters, and an independent t-test was used to compare the difference of the surgical effect on those parameters between the two groups. Possible linear regression relationship was analyzed among those variants. Results: There were 32 patients in the control group (age 57.93 ±9.07) and 62 patients in hallux valgus group (age 65.26± 12.84). In control group, except for HVA, there was no change in any of the above parameters between the pre and post surgical images; while in hallux rigidus group, the HVA, IMA, 1MCA, MC1A, and RCS were significantly reduced after surgery (p < 0.05). The RCS increased slightly in control group, but decreased significantly in hallux rigidus group (p < 0.05). Between the two groups, there was a significant difference in the impact of surgery on HVA, IMA, MC1A and RCS. In hallux rigidus group, correlation detected between pre-post operative IMA with HVA and MC1A, HVA with 1MCA, 1MCA with RCS and DMCA, MC1A with RCS, RCS with DMCA. Conclusion: Hallux MTP arthrodesis improved the alignment of the first-TMT joint in patients with hallux valgus, but this change had no correlation with either the pre and postoperative IMA or HVA changes. There was no significant improvement nor worsening of the TMT alignment in patients without hallux valgus

The Effects of Obesity and Bariatric Surgery on Rates of Upper Extremity Compression Neuropathies

Objectives:. To estimate the effects of obesity on all types of upper extremity compression neuropathies (UECN) (carpal tunnel syndrome and other median nerve, radial nerve, and ulnar nerve compression neuropathies) and to assess whether bariatric surgery modifies these effects. Background:. UECN are increasingly prevalent and decrease the quality of life of affected individuals. Studies suggest obesity as a risk factor for carpal tunnel syndrome, the most common type of UECN. Methods:. A retrospective cohort study was conducted using the PearlDiver Mariner Database, an all-payor claims database containing claims for over 53 million patients from 2010 to 2019 in all 50 US states. Rates and odds of all types of UECN were compared between 1:1:1 exact matched cohorts of obese patients who were medically managed, obese patients who underwent bariatric surgery, and nonobese patients (111,967 patients in each cohort). Results:. Compared with nonobese patients, patients with obesity were significantly more likely to develop any UECN (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.09–1.18), carpal tunnel syndrome (OR, 1.15; 95% CI, 1.10–1.30), and 2 or more UECN (OR, 1.34; 95% CI, 1.20–1.48). Compared with obese patients who were managed medically, obese patients who underwent bariatric surgery were significantly less likely to develop any UECN (OR, 0.87; 95% CI, 0.84–0.91) and carpal tunnel syndrome (OR, 0.85; 95% CI, 0.81–0.89). Conclusions:. Obese patients have higher odds of both single and concomitant UECN, specifically carpal tunnel syndrome, compared with nonobese patients. Bariatric surgery decreases the odds of developing UECN compared with obese patients not undergoing surgical intervention

Differential expression of cytochrome P450 omega-hydroxylase isoforms and their association with clinicopathological features in pancreatic ductal adenocarcinoma.

BACKGROUND: The cytochrome P450 (CYP) superfamily consists of enzymes that catalyze the oxidation of lipids, steroids, and drugs. In particular, the CYP4 family plays an essential role in lipid metabolism by the ω-hydroxylation of terminal ends of fatty acids. Disturbance of this system has been associated with increased angiogenesis, proliferation, and metastasis of several cancers. This study aimed to detect the expression of CYP4 isoforms (CYP4A11, CYP4F2, CYP4F3) in pancreatic ductal adenocarcinoma (PDA) and their association with clinicopathological features. METHODS: Pancreatic specimens were collected from 73 patients who underwent surgical resection at the Thomas Jefferson University Hospital. Quantitative polymerase chain reaction was used to examine the cytochrome P450 isoforms in PDA (n = 62), adjacent-normal (n = 30), and benign tissues (n = 11). Logistic regression models were used to analyze gene expression among tissue types. Spearman rank correlations were calculated for isoform expression and for age. Differences in expression by gender were assessed via t test. Other clinicopathological variables (diabetes, smoking, obesity, T stage, perineural invasion, nodal status) were analyzed by Wilcoxon rank sum. RESULTS: CYP4 expression for isoforms was significantly higher in PDA tissues versus matched-adjacent tissues (p \u3c 0.01). PDA tumors expressed significantly higher levels of CYP4F2 and CYP4F3 when compared to benign lesions (p \u3c 0.01). Significant associations were found between low levels of CYP4F2 and CYP4F3 and increased age of PDA patients. Interestingly, all isoforms were expressed at higher levels in male patients. CONCLUSIONS: Transcriptional upregulation of cytochrome P450 ω-hydroxylase suggests that these enzymes have the potential to be used as distinguishing markers in pancreatic pathology