The spines of pencil and lance urchins Heterocentrotus mammillatus and Phyllacanthus imperialis were studied as a model of light-weight material with high impact resistance.The complex and variable skeleton constructi...The spines of pencil and lance urchins Heterocentrotus mammillatus and Phyllacanthus imperialis were studied as a model of light-weight material with high impact resistance.The complex and variable skeleton construction ('stereom') of body and spines of sea urchins consists of highly porous Mg-bearing calcium carbonate.This basically brittle material with pronounced single-crystal cleavage does not fracture by spontaneous catastrophic device failure but by graceful failure over the range of tens of millimeter of bulk compression instead.This was observed in bulk compression tests and blunt indentation experiments on regular,infiltrated and latex coated sea urchin spine segments.Microstructural characterization was carried out using X-ray computer tomography,optical and scanning electron microscopy.The behavior is interpreted to result from the hierarchic structure of sea urchin spines from the rnacroscale down to the nanoscale.Guidelines derived from this study see ceramics with layered porosity as a possible biomimetic construction for appropriate applications.展开更多
Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting. Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to ha...Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting. Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to have superior fracture behavior under bulk compression compared to ceramics with uniform porosity.They fail in a cascading manner,absorbing high amounts of energy during extended compression paths.The porosity variation in an otherwise single phase material mimicks the architectural microstructure design of sea urchin spines of Heterocentrotus mammillatus,which are promising model materials for impact protection.展开更多
"Three Unities",derived from Aristotle’s unity of action,were developed to be the golden rule of drama or play creation by the classicism in the seventeenth century."Three Unities",to some extent,..."Three Unities",derived from Aristotle’s unity of action,were developed to be the golden rule of drama or play creation by the classicism in the seventeenth century."Three Unities",to some extent,provides the dramatic writing with certain law and criterion.However,the absolute standardization fetters the progress of artistic creation.Samuel Johnson,publishes the Preface to Shakespeare to propose the breakthrough of the shackles of"Three Unities"by the study of Shakespeare’s plays.This creative proposal accelerates the progress of the development of dramatic writing,thus,more excellent works writing in a more free way with a large scale appears in succession.展开更多
This paper attempts to look into some of Samuel Johnson＇s Lives of the English Poets （1925） and find out the common feature these biographical texts share. The close reading and detailed analysis demonstrate that S...This paper attempts to look into some of Samuel Johnson＇s Lives of the English Poets （1925） and find out the common feature these biographical texts share. The close reading and detailed analysis demonstrate that Samuel Johnson manages to redeem and restore the biographical subjects＇ （the poets＇） life, honor, and status in their different but similar biographies; that is, each biography is a redemptive text in its own way. In specific, the credible life story is re-presented with selected biographical materials, the poets＇ lives together with their achievements are reevaluated under Johnson＇s corrective observation, and Johnson＇s empathy with the poets reestablishes the reader＇s understanding of the poets＇ literary careers.展开更多
Though many scholars and critics have made efforts explaining its connotation and influence from philosophical,religious and historical perspective about Samuel Johnson’s statement that Shakespeare is“A Poet of Nat...Though many scholars and critics have made efforts explaining its connotation and influence from philosophical,religious and historical perspective about Samuel Johnson’s statement that Shakespeare is“A Poet of Nature”,it is still worthy of discussion.As a Neoclassical critic,Johnson revealed Shakespeare’s genuine faculties through comparison with Homer following John Dryden and Alexzander Popeto illustrate the dramatic writing process.Then Shakespeare’s genius in natural acquisition of human nature and literature tradition,adaptation and concatenation to make something novelty,and selection of original language and characters is exemplified to analyze mixed genre,irregular structure,natural dialogue and characters under the principle of general nature.展开更多
The metaphysical poetry,as a rather influential literary school,plays a momentous andpredominant part in eariy seventeenth century English literature.The marked quality ofmetaphysical poetry,as practiced by Donne and ...The metaphysical poetry,as a rather influential literary school,plays a momentous andpredominant part in eariy seventeenth century English literature.The marked quality ofmetaphysical poetry,as practiced by Donne and his successors,is their philosophical subtlety orintellectual rigor,while the quintessence of which consists in its peculiar blend of thought andpassion of realistic violence and meditative refinements.Doctor Johnson accused the展开更多
Aim of Study: Gonadal hormones exert a profound influence on the development, structure and function of the sexual organs. The testosterone is one of the androgens that plays an essential role in the development of se...Aim of Study: Gonadal hormones exert a profound influence on the development, structure and function of the sexual organs. The testosterone is one of the androgens that plays an essential role in the development of sexual organs in male mammals. Therefore, the present study was undertaken to evaluate the testosterone levels and developmental pattern of the penile spines and seminiferous tubules during early postnatal life of Wistar rats. Methods and Materials: At 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days after birth, penile and testicular tissues of male rats were dissected out and fixed for histological study and plasma testosterone levels were determined using high resolution chromatography. Results: An increase in the number of penile follicles, primarily in the distal region of the penis, was observed from postnatal days 14 to 42, followed by a gradual decrease. Penile spines were absent from birth until the first growth peak, which was observed at 42 postnatal days. Both testicular weight and the area of seminiferous tubules showed gradual increases before achieving their highest values at 42 postnatal days. Similarly, a gradual increase in testosterone levels was detected from day 28, with a peak at 42 postnatal days. Conclusions: These data show a temporal association between the development of the penile spines and testicular tissue with gradual increases in testosterone levels. These results may contribute to a better understanding of the behavioral, hormonal and morphological changes underlying sexual maturation in male rats.展开更多
Traumatic brain injury is an important global public health problem.Traumatic brain injury not only causes neural cell death,but also induces dendritic spine degeneration.Spared neurons from cell death in the injured ...Traumatic brain injury is an important global public health problem.Traumatic brain injury not only causes neural cell death,but also induces dendritic spine degeneration.Spared neurons from cell death in the injured brain may exhibit dendrite damage,dendritic spine degeneration,mature spine loss,synapse loss,and impairment of activity.Dendritic degeneration and synapse loss may significantly contribute to functional impairments and neurological disorders following traumatic brain injury.Normal function of the nervous system depends on maintenance of the functionally intact synaptic connections between the presynaptic and postsynaptic spines from neurons and their target cells.During synaptic plasticity,the numbers and shapes of dendritic spines undergo dynamic reorganization.Enlargement of spine heads and the formation and stabilization of new spines are associated with long-term potentiation,while spine shrinkage and retraction are associated with long-term depression.Consolidation of memory is associated with remodeling and growth of preexisting synapses and the formation of new synapses.To date,there is no effective treatment to prevent dendritic degeneration and synapse loss.This review outlines the current data related to treatments targeting dendritic spines that propose to enhance spine remodeling and improve functional recovery after traumatic brain injury.The mechanisms underlying proposed beneficial effects of therapy targeting dendritic spines remain elusive,possibly including blocking activation of Cofilin induced by beta amyloid,Ras activation,and inhibition of GSK-3 signaling pathway.Further understanding of the molecular and cellular mechanisms underlying synaptic degeneration/loss following traumatic brain injury will advance the understanding of the pathophysiology induced by traumatic brain injury and may lead to the development of novel treatments for traumatic brain injury.展开更多
Purpose To report clinical variations and the natural course of melanocytoma o f the optic disc. Patients and methods A retrospective study was conducted on a consecutive series of patients with melanocytoma of the op...Purpose To report clinical variations and the natural course of melanocytoma o f the optic disc. Patients and methods A retrospective study was conducted on a consecutive series of patients with melanocytoma of the optic disc who were evaluated at the Ocular Oncology Service at Wills Eye Hospital. Demographic information and variations i n appearance and size of the tumor and local ocular complications were noted. Fr equency of tumor growth and malignant transformation was recorded. Clinical fact ors, including patient data and tumor features, were analyzed for their impact o n visual acuity loss of 2 or more Snellen lines and the tumor growth, using Cox proportional hazards regression models. Kaplan-Meier survival estimates of prob ability of visual acuity loss of 2 or more Snellen lines and probability of tumo r growth were performed as a function of time from the initial examination. Main outcome measures Visual acuity loss of 2 or more Snellen lines, tumor growth, a nd malignant transformation of the tumor. Results There were 115 patients (116 e yes) with melanocytoma of the optic disc. The mean age at diagnosis was 50 years ; 38%of patients were male and 62%of patients were female; 65%of patients wer e white, 29%of patients were African American, and 6%of patients were Asian, H ispanic, Indian, or Arabic. The lesion was unilateral in 99%of patients. Visual symptoms that seemed to be related to the melanocytoma were present in 24%of p atients, and an afferent pupillary defect was noted in 9%of patients. Associate d ocular abnormalities included ocular melanocytosis (8%), racial melanosis (7 %), optic nerve hypoplasia (2%), and retinitis pigmentosa (1%). The melanocyt oma was dark brown to black in 100%of patients. The mean tumor diameter was 2 m m and the mean thickness was 1 mm. Associated findings included a choroidal comp onent (54%), retinal component (30%), optic disc edema (25%), retinal edema ( 16%), localized subretinal fluid (14%), retinal exudation (12%), retinal hemo rrhage (5%), vitreous seeds (4%), and retinal vein obstruction (3%). Fluoresc ein and indocyanine green angiography typically showed persistent hypofluorescen ce of the lesion. Using Kaplan-Meier survival curves, related visual loss occur red in 18%of patients by 10 years, and minor tumor enlargement occurred in 11% of patients by 5 years and in 32%of patients by 10 years. Malignant transformat ion was documented in 2 patients (2%). Conclusions Although melanocytoma of the optic disc generally is considered to be a benign, stationary lesion, it can pr oduce several local complications, can cause visual loss, can grow slowly, and, rarely, can undergo malignant transformation into melanoma. Patients with optic disc melanocytoma should undergo periodic ocular examination.展开更多
Objective To investigate the accuracy and feasibility of transpedicular screw placement assisted by the navigation templates in cadaveric thoracic spines.Methods Twenty thoracic cadavers specimens were randomly divide...Objective To investigate the accuracy and feasibility of transpedicular screw placement assisted by the navigation templates in cadaveric thoracic spines.Methods Twenty thoracic cadavers specimens were randomly divided into two展开更多
文摘The spines of pencil and lance urchins Heterocentrotus mammillatus and Phyllacanthus imperialis were studied as a model of light-weight material with high impact resistance.The complex and variable skeleton construction ('stereom') of body and spines of sea urchins consists of highly porous Mg-bearing calcium carbonate.This basically brittle material with pronounced single-crystal cleavage does not fracture by spontaneous catastrophic device failure but by graceful failure over the range of tens of millimeter of bulk compression instead.This was observed in bulk compression tests and blunt indentation experiments on regular,infiltrated and latex coated sea urchin spine segments.Microstructural characterization was carried out using X-ray computer tomography,optical and scanning electron microscopy.The behavior is interpreted to result from the hierarchic structure of sea urchin spines from the rnacroscale down to the nanoscale.Guidelines derived from this study see ceramics with layered porosity as a possible biomimetic construction for appropriate applications.
基金funded by European sources within the ERASMUS-SOCRATES program
文摘Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting. Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to have superior fracture behavior under bulk compression compared to ceramics with uniform porosity.They fail in a cascading manner,absorbing high amounts of energy during extended compression paths.The porosity variation in an otherwise single phase material mimicks the architectural microstructure design of sea urchin spines of Heterocentrotus mammillatus,which are promising model materials for impact protection.
文摘"Three Unities",derived from Aristotle’s unity of action,were developed to be the golden rule of drama or play creation by the classicism in the seventeenth century."Three Unities",to some extent,provides the dramatic writing with certain law and criterion.However,the absolute standardization fetters the progress of artistic creation.Samuel Johnson,publishes the Preface to Shakespeare to propose the breakthrough of the shackles of"Three Unities"by the study of Shakespeare’s plays.This creative proposal accelerates the progress of the development of dramatic writing,thus,more excellent works writing in a more free way with a large scale appears in succession.
文摘This paper attempts to look into some of Samuel Johnson＇s Lives of the English Poets （1925） and find out the common feature these biographical texts share. The close reading and detailed analysis demonstrate that Samuel Johnson manages to redeem and restore the biographical subjects＇ （the poets＇） life, honor, and status in their different but similar biographies; that is, each biography is a redemptive text in its own way. In specific, the credible life story is re-presented with selected biographical materials, the poets＇ lives together with their achievements are reevaluated under Johnson＇s corrective observation, and Johnson＇s empathy with the poets reestablishes the reader＇s understanding of the poets＇ literary careers.
文摘Though many scholars and critics have made efforts explaining its connotation and influence from philosophical,religious and historical perspective about Samuel Johnson’s statement that Shakespeare is“A Poet of Nature”,it is still worthy of discussion.As a Neoclassical critic,Johnson revealed Shakespeare’s genuine faculties through comparison with Homer following John Dryden and Alexzander Popeto illustrate the dramatic writing process.Then Shakespeare’s genius in natural acquisition of human nature and literature tradition,adaptation and concatenation to make something novelty,and selection of original language and characters is exemplified to analyze mixed genre,irregular structure,natural dialogue and characters under the principle of general nature.
文摘The metaphysical poetry,as a rather influential literary school,plays a momentous andpredominant part in eariy seventeenth century English literature.The marked quality ofmetaphysical poetry,as practiced by Donne and his successors,is their philosophical subtlety orintellectual rigor,while the quintessence of which consists in its peculiar blend of thought andpassion of realistic violence and meditative refinements.Doctor Johnson accused the
文摘Aim of Study: Gonadal hormones exert a profound influence on the development, structure and function of the sexual organs. The testosterone is one of the androgens that plays an essential role in the development of sexual organs in male mammals. Therefore, the present study was undertaken to evaluate the testosterone levels and developmental pattern of the penile spines and seminiferous tubules during early postnatal life of Wistar rats. Methods and Materials: At 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days after birth, penile and testicular tissues of male rats were dissected out and fixed for histological study and plasma testosterone levels were determined using high resolution chromatography. Results: An increase in the number of penile follicles, primarily in the distal region of the penis, was observed from postnatal days 14 to 42, followed by a gradual decrease. Penile spines were absent from birth until the first growth peak, which was observed at 42 postnatal days. Both testicular weight and the area of seminiferous tubules showed gradual increases before achieving their highest values at 42 postnatal days. Similarly, a gradual increase in testosterone levels was detected from day 28, with a peak at 42 postnatal days. Conclusions: These data show a temporal association between the development of the penile spines and testicular tissue with gradual increases in testosterone levels. These results may contribute to a better understanding of the behavioral, hormonal and morphological changes underlying sexual maturation in male rats.
文摘Traumatic brain injury is an important global public health problem.Traumatic brain injury not only causes neural cell death,but also induces dendritic spine degeneration.Spared neurons from cell death in the injured brain may exhibit dendrite damage,dendritic spine degeneration,mature spine loss,synapse loss,and impairment of activity.Dendritic degeneration and synapse loss may significantly contribute to functional impairments and neurological disorders following traumatic brain injury.Normal function of the nervous system depends on maintenance of the functionally intact synaptic connections between the presynaptic and postsynaptic spines from neurons and their target cells.During synaptic plasticity,the numbers and shapes of dendritic spines undergo dynamic reorganization.Enlargement of spine heads and the formation and stabilization of new spines are associated with long-term potentiation,while spine shrinkage and retraction are associated with long-term depression.Consolidation of memory is associated with remodeling and growth of preexisting synapses and the formation of new synapses.To date,there is no effective treatment to prevent dendritic degeneration and synapse loss.This review outlines the current data related to treatments targeting dendritic spines that propose to enhance spine remodeling and improve functional recovery after traumatic brain injury.The mechanisms underlying proposed beneficial effects of therapy targeting dendritic spines remain elusive,possibly including blocking activation of Cofilin induced by beta amyloid,Ras activation,and inhibition of GSK-3 signaling pathway.Further understanding of the molecular and cellular mechanisms underlying synaptic degeneration/loss following traumatic brain injury will advance the understanding of the pathophysiology induced by traumatic brain injury and may lead to the development of novel treatments for traumatic brain injury.
文摘Purpose To report clinical variations and the natural course of melanocytoma o f the optic disc. Patients and methods A retrospective study was conducted on a consecutive series of patients with melanocytoma of the optic disc who were evaluated at the Ocular Oncology Service at Wills Eye Hospital. Demographic information and variations i n appearance and size of the tumor and local ocular complications were noted. Fr equency of tumor growth and malignant transformation was recorded. Clinical fact ors, including patient data and tumor features, were analyzed for their impact o n visual acuity loss of 2 or more Snellen lines and the tumor growth, using Cox proportional hazards regression models. Kaplan-Meier survival estimates of prob ability of visual acuity loss of 2 or more Snellen lines and probability of tumo r growth were performed as a function of time from the initial examination. Main outcome measures Visual acuity loss of 2 or more Snellen lines, tumor growth, a nd malignant transformation of the tumor. Results There were 115 patients (116 e yes) with melanocytoma of the optic disc. The mean age at diagnosis was 50 years ; 38%of patients were male and 62%of patients were female; 65%of patients wer e white, 29%of patients were African American, and 6%of patients were Asian, H ispanic, Indian, or Arabic. The lesion was unilateral in 99%of patients. Visual symptoms that seemed to be related to the melanocytoma were present in 24%of p atients, and an afferent pupillary defect was noted in 9%of patients. Associate d ocular abnormalities included ocular melanocytosis (8%), racial melanosis (7 %), optic nerve hypoplasia (2%), and retinitis pigmentosa (1%). The melanocyt oma was dark brown to black in 100%of patients. The mean tumor diameter was 2 m m and the mean thickness was 1 mm. Associated findings included a choroidal comp onent (54%), retinal component (30%), optic disc edema (25%), retinal edema ( 16%), localized subretinal fluid (14%), retinal exudation (12%), retinal hemo rrhage (5%), vitreous seeds (4%), and retinal vein obstruction (3%). Fluoresc ein and indocyanine green angiography typically showed persistent hypofluorescen ce of the lesion. Using Kaplan-Meier survival curves, related visual loss occur red in 18%of patients by 10 years, and minor tumor enlargement occurred in 11% of patients by 5 years and in 32%of patients by 10 years. Malignant transformat ion was documented in 2 patients (2%). Conclusions Although melanocytoma of the optic disc generally is considered to be a benign, stationary lesion, it can pr oduce several local complications, can cause visual loss, can grow slowly, and, rarely, can undergo malignant transformation into melanoma. Patients with optic disc melanocytoma should undergo periodic ocular examination.
文摘Objective To investigate the accuracy and feasibility of transpedicular screw placement assisted by the navigation templates in cadaveric thoracic spines.Methods Twenty thoracic cadavers specimens were randomly divided into two
