Sub-femto-Newton sensing torsion pendulum for detection of light force.

Mechanical oscillators are widely used in many fields of physics, including ultrahigh precision measurements, gravity experiments, and optical mechanical systems. A sub-gram-scale silicon wafer is suspended by a tungsten wire with a diameter of 8 µm, forming a torsion pendulum to detect the laser radiation pressure. We demonstrate the application of a low-frequency, highly sensitive torsion pendulum for the measurement of light forces. In the feedback cooling state, the system exhibits a force sensitivity at the end of the pendulum close to 0.1 fN, approaches the thermal noise limit, and reaches the detection level of the laser radiation pressure of 60 nW.

[Revision of submucous resection of nasal septum].

OBJECTIVE: To explore the clinical significance and surgical technique for revisionary submucous resection of nasal septum. METHODS: Thirty-two patients who had undergone nasal septal resection were evaluated rhinologically and the causes of unsuccessful septoplasty were analysed . Based on the location and extent of deviation, the status of residual cartilage and bone, and the age of the patients, one of three incisions was chosen during septal surgeries: (1) For 5 cases with anterior, 1 with inferior and 14 with superior deviation, a "U" shaped incision at the left side of anterior edge of septum cartilage was used. (2) For 8 cases with posterior and 2 with superior deviation, the site of the incision was located just anterior to the deviation, with the aid of endoscope. (3) For 2 cases with anteroinferior deviation, because of their young age, a sublabial incision was made to surge the mucosa of the septum and base of nasal cavity, the otological electronic drill was then used. RESULTS: Revision nasal septoplasty was successful in all cases. The symptoms resulting from septal deviation disappeared or significantly relieved. Following successful revision surgery, the treatment outcomes of concomitant nasal and/or sinusal diseases also significantly improved. CONCLUSION: Revision nasal septoplasty requires different approaches depending on different clinical characteristics. A successful correction of septal deviation can not only relieve the symptoms derived from deviation, but also be of significance for the treatment of concomitant nasal and/or sinusal diseases.

Critical slowing down of the kinetic Gaussian model on hierarchical lattices.

The critical slowing down of the kinetic Gaussian model on hierarchical lattices is studied by means of a real-space time-dependent renormalization-group transformation. The dynamic critical exponent z and the exponent Delta are calculated. For hierarchical lattices with reducible generators, both the dynamic critical exponent z and the exponent Delta are independent of the fractal dimension Df of the lattice, the number of branches m, and the number of bonds per branch b of the generator--i.e., z = 2 and Delta = 1. For hierarchical lattices with irreducible generators, the exponent Delta is the same--i.e., Delta = 1; however, the dynamic critical exponent z is dependent on the concrete geometrical structure of these lattices. In addition, it was found that the lattice dependence of the correlation-length critical exponent nu is the same as that of the dynamic critical exponent z. Finally we give a brief discussion about universality for critical dynamics.

Phase transitions of the Ashkin-Teller model including antiferromagnetic interactions on a type of diamond hierarchical lattice.

Using the real-space renormalization-group transformation, we study the phase transitions of the Ashkin-Teller model including the antiferromagnetic interactions on a type of diamond hierarchical lattices, of which the number of bonds per branch of the generator is odd. The isotropic Ashkin-Teller model and the anisotropic one are, respectively, investigated. We find that the phase diagram, for the isotropic Ashkin-Teller model, consists of five phases, two of which are associated with the partially antiferromagnetic ordering of the system, while the phase diagram, for the anisotropic Ashkin-Teller model, contains 11 phases, six of which are related to the partially antiferromagnetic ordering of the system. The correlation length critical exponents and the crossover exponents are also calculated.

Phase transitions of the anisotropic Ashkin-Teller model on a family of diamond-type hierarchical lattices.

The phase transitions of the anisotropic Ashkin-Teller model on a family of diamond-type hierarchical lattices is studied by means of the transfer-matrix method and the real-space renormalization-group transformation. We find that the phase diagram, for the ferromagnetic case, consists of five phases, i.e., the fully disordered paramagnetic phase P, the fully ordered ferromagnetic phase F, and three partially ordered ferromagnetic phases F(s), F(sigma), and F(s sigma), as well as ten nontrivial fixed points. The correlation length critical exponents and the crossover exponents are also calculated. In addition, we also investigate the variations of the critical exponents with the fractal dimension d(f), the number of branches m, and the number of bonds per branch b of the generator of the family of diamond-type hierarchical lattices. Finally we give a brief discussion about universality.