For two positive integers k and d such that k ≥ 2d, Gkd is the graph with vertex set {0,1, ...,k-1} in which ij is an edge if and only if d ≤ |i-j| ≤ k-d. Clearly, Gk1 is a complete graph of k vertices and we alway...For two positive integers k and d such that k ≥ 2d, Gkd is the graph with vertex set {0,1, ...,k-1} in which ij is an edge if and only if d ≤ |i-j| ≤ k-d. Clearly, Gk1 is a complete graph of k vertices and we always assume d ≥ 2 in the following. It is easy to see (also [1]) that a graph G is (k, d)-colorable if and only if there exists a homomorphism from G to Gkd.展开更多
Schwannomas are peripheral nerve tumors that are typically solitary and benign.Their diagnosis is largely based on surgically resected specimens.Recently,a number of case reports have indicated that retroperitoneal sc...Schwannomas are peripheral nerve tumors that are typically solitary and benign.Their diagnosis is largely based on surgically resected specimens.Recently,a number of case reports have indicated that retroperitoneal schwannomas could be diagnosed with endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA).We report the diagnosis of three cases of schwannoma using EUS-FNA.Subjects were two males and one female,ages 22,40,and 46 years,respectively,all of whom were symptom-free.Imaging findings showed well-circumscribed round tumors.However,as the tumors could not be diagnosed using these findings alone,EUS-FNA was performed.Hematoxylin-eosin staining of the resulting tissue fragments revealed bland spindle cells with nuclear palisading.There was no disparity in nuclear sizes.Immunostaining revealed S-100 protein positivity and all cases were diagnosed as schwannomas.Ki-67 indexes were 3%-15%,2%-3%,and 3%,respectively.No case showed any signs of malignancy.As most schwannomas are benign tumors and seldom become malignant,we observed these patients without therapy.All tumors demonstrated no enlargement and no change in characteristics.Schwannomas are almost always benign and can be observed following diagnosis by EUS-FNA.展开更多
基金NSFC(No.60172003) Natural Science Foundation of Shandong Province(No.Z2000A02).
文摘For two positive integers k and d such that k ≥ 2d, Gkd is the graph with vertex set {0,1, ...,k-1} in which ij is an edge if and only if d ≤ |i-j| ≤ k-d. Clearly, Gk1 is a complete graph of k vertices and we always assume d ≥ 2 in the following. It is easy to see (also [1]) that a graph G is (k, d)-colorable if and only if there exists a homomorphism from G to Gkd.
文摘Schwannomas are peripheral nerve tumors that are typically solitary and benign.Their diagnosis is largely based on surgically resected specimens.Recently,a number of case reports have indicated that retroperitoneal schwannomas could be diagnosed with endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA).We report the diagnosis of three cases of schwannoma using EUS-FNA.Subjects were two males and one female,ages 22,40,and 46 years,respectively,all of whom were symptom-free.Imaging findings showed well-circumscribed round tumors.However,as the tumors could not be diagnosed using these findings alone,EUS-FNA was performed.Hematoxylin-eosin staining of the resulting tissue fragments revealed bland spindle cells with nuclear palisading.There was no disparity in nuclear sizes.Immunostaining revealed S-100 protein positivity and all cases were diagnosed as schwannomas.Ki-67 indexes were 3%-15%,2%-3%,and 3%,respectively.No case showed any signs of malignancy.As most schwannomas are benign tumors and seldom become malignant,we observed these patients without therapy.All tumors demonstrated no enlargement and no change in characteristics.Schwannomas are almost always benign and can be observed following diagnosis by EUS-FNA.
