An acoustic guidance method for pedicle screw placement during spine fixation surgery was recently investigated, with a view toward preventing complications such as injury to the spinal cord, thecal sac, and spinal nerve roots due to screw misplacement. The method relies upon the change in the ultrasound amplitude reflected at different sites—from the outer posterior cortex, through the pedicle, and towards the distal ventral cortex. The amplitude change was empirically observed through in vitro measurement of ultrasound amplitude at the different sites by inserting a 2.5-MHz single element transducer into a vertebral body through insertion pathway created by an advancing screw. This paper provides a theoretical and experimental rationale behind these empirical findings and distance-dependent correlation coefficients between amplitude and bone mineral density within the vertebral body, which approached 97%. 相似文献
We prove that for any bounded type irrational number 0θ1,the boundary of the Siegel disk of fα(z)=e2πiθsin(z)+αsin3(z),α∈C,which centered at the origin,is a quasicircle passing through 2,4 or 6 critical points of fαcounted with multiplicity. 相似文献
For a hyperbolic knot in the -sphere, at most finitely many Dehn surgeries yield non-hyperbolic -manifolds. As a typical case of such an exceptional surgery, a toroidal surgery is one that yields a closed -manifold containing an incompressible torus. The slope corresponding to a toroidal surgery, called a toroidal slope, is known to be integral or half-integral. We show that the distance between two integral toroidal slopes for a hyperbolic knot, except the figure-eight knot, is at most four.
Sarcoidosis can affect the larynx as a manifestation of systemic disease or as isolated laryngeal involvement. Classically, laryngeal involvement affects the supraglottis, and less commonly the subglottis, and true vocal fold involvement is rare. The clinical course is often highlighted by frequent exacerbations and remissions that, when associated with vague complaints and constitutional symptoms, are probably the greatest contributor to delayed presentation and diagnosis. We describe an unusual case of sarcoidosis that presented after a long and protracted clinical course as an isolated submucosal vocal fold mass requiring deep biopsy for diagnosis. A review of the literature with emphasis on diagnosis, appropriate airway management, and treatment is presented. 相似文献
Hepatectomy is one of the main treatments for hepatocellular carcinoma (HCC). However, because microscopic tumor residues are often present after surgery, the recurrence rate of HCC remains extremely high. A multimodality imaging‐guided multifunctional nanoparticle, indocyanine‐green–gadolinium–copper sulfide@bovine‐serum‐albumin–epithelial‐cell‐adhesion molecule (EpCAM), is developed for HCC treatment based on a novel theranostic strategy. After intravenous injection of these nanoparticles into HCC‐bearing mice, remarkably selective accumulation and highly efficient retention of the nanoparticles in tumor sites are observed. This is due to the EpCAM's specific targeting ability, which also results in enhanced HCC contrast in a tri‐modal visualization, which unites magnetic resonance, photoacoustic, and fluorescence imaging. Moreover, nanoparticle uptake into the HCC allows photothermal therapy (PTT) as an interoperative adjuvant strategy for further eliminating possible microscopic residues and boosting HCC surgery outcomes. This theranostic strategy not only helps with precise diagnosis of HCC but enables intraoperatively imaging guidance for accurate tumor resection. Moreover, postoperation longitudinal observation demonstrates that intraoperative imaging‐guided resection alongside a PTT‐integrated treatment strategy can result in a significant improvement of overall survival rate. These multifunctional EpCAM‐targeting nanoparticles may respresent a novel theranostic strategy to improve postsurgical HCC treatment. 相似文献
A standard convexity condition on the boundary of a symplectic manifold involves an induced positive contact form (and contact structure) on the boundary; the corresponding concavity condition involves an induced negative contact form. We present two methods of symplectically attaching -handles to convex boundaries of symplectic -manifolds along links transverse to the induced contact structures. One method results in concave boundaries and depends on a fibration of the link complement over ; in this case the handles can be attached with any framing larger than a lower bound determined by the fibration. The other method results in a weaker convexity condition on the new boundary (sufficient to imply tightness of the new contact structure), and in this case the handles can be attached with any framing less than a certain upper bound. These methods supplement methods developed by Weinstein and Eliashberg for attaching symplectic -handles along Legendrian knots.
Let be a finite group and let be a degree 1, -framed map such that and are simply connected, closed, oriented, smooth manifolds of dimension and such that the dimension of the singular set of the -space is at most . In the previous article, assuming is -connected, we defined the -equivariant surgery obstruction in a certain abelian group. There it was shown that if then is -framed cobordant to a homotopy equivalence . In the present article, we prove that the obstruction is a -framed cobordism invariant. Consequently, the -surgery obstruction is uniquely associated to above even if it is not -connected.
We generalize a theorem of Finkelstein and Moriah and show that if a link has a -plat projection satisfying certain conditions, then its complement contains some closed essential surfaces. In most cases these surfaces remain essential after any totally nontrivial surgery on .
On a Riemannian manifold X, we consider aK+s, where a is a nonnegative constant, K is the sectional curvature and s is the scalar curvature. It is shown that if X admits a metric with aK+s > 0, then so does any manifold obtained from X by surgeries of codimension 3. This implies the existence of such metrics on certain compact simply connected manifolds of dimension 5 by using the cobordism argument. We also study the corresponding minimal volume problem. As a corollary, we derive that every compact simply connected manifold of dimension 5 and every compact complex surface of Kodaira dimension 1 whose minimal model is not of Class VII collapse with aK+s bounded below. 相似文献