Our data suggest that interactions between biomarkers in AD result in a 2-phase phenomenon of pathological cortical thickening associated with low CSF Aβ, followed by atrophy once CSF p-tau becomes abnormal. These interactions should be considered in clinical trials in preclinical AD, both when selecting patients and when using MRI as a surrogate marker of efficacy.

Extratesticular lesions are common incidental findings at ultrasonography (US) among men and boys. Most lesions originate from or depend on the tunica vaginalis, a mesothelium-lined sac with a visceral layer and a parietal layer. The tunica vaginalis is formed when the superior portion of the processus vaginalis closes during embryologic development. Abnormal closure of the processus vaginalis leads to congenital anomalies of the tunica vaginalis, such as complete or partial patency of the processus vaginalis, spermatic cord hydrocele, and inguinoscrotal hernia. The proximity of the visceral layer to the testis explains the reactive involvement seen in epididymo-orchitis, with resultant pyocele or abscess formation. The tunica vaginalis also may be affected by inflammatory and traumatic disorders such as scrotal calculi, fibrous pseudotumor, or hematocele. These lesions manifest as solid or heterogeneous tumorlike masses. Lesions of mesothelial origin, such as adenomatoid tumor, tunica cyst, and mesothelioma, may involve the tunica vaginalis. Entrapped mesenchymal cells can lead to lipoma, leiomyoma, or sarcoma, although these tumors are uncommon in the tunica vaginalis. US is not useful for differentiating between benign and malignant tumors; however, some characteristic findings may help in planning the best surgical approach. Knowledge of the embryologic development, anatomic relationships, and pathologic disorders of the tunica vaginalis is essential to narrow the differential diagnosis of an extratesticular lesion. In most cases, US findings in combination with clinical assessment can indicate whether nonsurgical management or testis-sparing surgery is warranted.

The geometric topology of the generic intersection of two homogeneous coaxial quadrics in R n was studied in [LdM1] where it was shown that its intersection with the unit sphere is in most cases diffeomorphic to a triple product of spheres or to the connected sum of sphere products. The proof involved a geometric description of the group actions on them and of their polytope quotients as well as a splitting of the homology groups of those manifolds. It also relied heavily on a normal form for them and many related computations. The part about group actions, polytopes and homology splitting was equally valid for the intersection of any number of such quadrics, but the obstacle to extending the main result for more than two turned out to be the hopeless-looking problem of finding their normal forms, close to that of classifying all simple polytopes. 1) Whether they can always be built up from spheres by repeatedly taking products or connected sums: they produced new examples for any k which are so, but also showed how to construct many cases which are not. Many interesting questions arose, including a specific conjecture.2) The transition between different topological types when the generic condition is broken at some point of a deformation (wall-crossing).3) A product rule of their cohomology ring (in the spirit of the description of the homology of Z given in [LdM1]) and its applications to question 1).Meanwhile, and independently, in [D-J] essentially the same manifolds were constructed in a more abstract way, where the main objective was to study the algebraic topology of some important quotients of them called initially toric manifolds and now quasitoric manifolds. This article originated an important development through the work of many authors, and there is a vast and deep literature along those lines for which the reader is referred to [B-P]. Yet for a long time no interchange occurred between the two lines of research involving the same objects, until small connections appeared in the final version of [B-M] and in [D-S]. In particular, it turned out that examples relevant to question 1) above were known to these authors (see [B2]), and in [B1] Baskakov had a product rule for the cohomology ring, similar but dual to that of [B-M] mentioned in 3) above. All those examples were independent and more or less simultaneous, yet both product rules followed from an earlier computation by Buchstaber and Panov of the cohomology ring 1 .One recent expression of the line of research derived from [D-J] is the article [B-B-C-G] where a far-reaching generalization is made and a general geometric splitting formula is derived that is, in particular, a very good tool for understanding the relations among the homology groups of different spaces. This understanding turned out to be fundamental for us in tracing a way through the abstract situation of the intersection of k > 2 quadrics, thus combining efficiently both approaches to the subject as expressed in [LdM1] and [B-B-C-G] to obtain the results in the present article. ...

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Sonography is useful in the diagnostic workup for MP. The characteristic sonographic features of MP (well-defined mass, homogeneous hyperechogenicity of the mass, nondeviated vessels within the mass, and displaced bowel loops) correlate well with CT findings.