Abstract In recent years, as a new type of gob-side entry retaining method, roadway automatically formed by roof cutting and pressure releasing (RAFRCPR) has been widely used in China. Under the condition deep mining, deformation gangue rib is difficult to control, it for traditional I-shaped steel provide needed support. To effectively control rib, U-shaped retractable prevention structure (UR...

Conjectural search queries (is python case sensitive, is millennium stadium heated) embody attempts by Web users to verify whether a particular property (soluble in water?, case sensitive?, heated?) does or does not apply to a particular instance (iodine, python, millennium stadium). This paper considers such queries to be a data source of attributes of open-domain classes. Conjectural attribut...

a module m is called epi-retractable if every submodule of m is a homomorphic image of m. dually, a module m is called co-epi-retractable if it contains a copy of each of its factor modules. in special case, a ring r is called co-pli (resp. co-pri) if rr (resp. rr) is co-epi-retractable. it is proved that if r is a left principal right duo ring, then every left ideal of r is an epi-retractable ...

We call a module  essentially retractable if HomR for all essential submodules N of M. For a right FBN ring R, it is shown that: (i)  A non-zero module  is retractable (in the sense that HomR for all non-zero ) if and only if certain factor modules of M are essentially retractable nonsingular modules over R modulo their annihilators. (ii)  A non-zero module  is essentially retractable if and on...

A new versatile transbronchial needle, the modified type 2B retractable needle, was used for the staging and diagnosis of bronchogenic carcinoma. It combines the advantages of its predecessors, the fixed type 1A needle and the retractable type 2A needle, such as convenience of usage and the added ability to sample peripheral as well as central lesions. The new modified type 2B retractable needl...