The writhing number of a space curve.

نویسنده

  • F B Fuller
چکیده

A geometric invariant of a space curve, the writhing number, is defined and studied. For the central curve of a twisted cord the writhing number measures the extent to which coiling of the central curve has relieved local twisting of the cord. This study originated in response to questions that arise in the study of supercoiled double-stranded DNA rings.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Surface runoff estimation in an upper watershed using geo-spatial based soil conservation service-curve number method

Runoff assessment and estimation is crucial for watershed management as it provides information that is needed to expedite the course of watershed planning and development. The most commonly used model due to its simplicity and versatility in runoff estimation is the soil conservation service curve number developed by the United States Department of Agriculture. The study estimates the surface ...

متن کامل

Upper Bounds for the Writhing of Knots and the Helicity of Vector Fields Jason Cantarella, Dennis Deturck, and Herman Gluck to Joan Birman on Her 70th Birthday

The writhing number of a curve in Euclidean 3-space, introduced by Călugăreanu (1959-61) and named by Fuller (1971), is the standard measure of the extent to which the curve wraps and coils around itself; it has proved its importance for molecular biologists in the study of knotted duplex DNA and of the enzymes which affect it. The helicity of a vector field defined on a domain in Euclidean 3-s...

متن کامل

بررسی اثر استرادیول و عصاره هیدروالکلی دانه خرفه بر درد حاصل از القای تست رایتینگ در موش‌های سوری ماده

Background and Objective: Studies have shown that estradiol and Portulaca oleracea extract have analgesic effects. The main aim of this study was to investigate the effect of co-administration of estradiol and Portulaca oleracea seed hydroalcoholic extract on pain induced by writhing test in female mice. Materials and Methods: In this experimental study, 78 female balb c mice were randomly d...

متن کامل

Parallel Transport Frame in 4 -dimensional Euclidean Space

In this work, we give parallel transport frame of a curve and we introduce the relations between the frame and Frenet frame of the curve in 4-dimensional Euclidean space. The relation which is well known in Euclidean 3-space is generalized for the …rst time in 4-dimensional Euclidean space. Then we obtain the condition for spherical curves using the parallel transport frame of them. The conditi...

متن کامل

بررسی اثر و مکانیسم های اوپیوییدی و دوپامینرژیک دکسترومتورفان بر پاسخ درد ایجاد شده با اسید استیک در موش ها با استفاده از تست Writhing شکمی

Background and purpose: Dextromenthorphan is a NMDÂ receptor antagonist in the glutamatergic system. Çurrently, there are good reports showing that the glutamatergic NMDÂ receptor mechanism modulates endogenous opiods and dopamine actions in several brain regions. This effect may in part change pain threshold in various analgesic tests. The purpose of the present study is to determine the mod...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Proceedings of the National Academy of Sciences of the United States of America

دوره 68 4  شماره 

صفحات  -

تاریخ انتشار 1971