ABSTRACT
We study adiabatic quantum pumps on time scales that are short relative to the cycle of the pump. In this regime the pump is characterized by the matrix of energy shift which we introduce as the dual to Wigner's time delay. The energy shift determines the charge transport, the dissipation, the noise, and the entropy production. We prove a general lower bound on dissipation in a quantum channel and define optimal pumps as those that saturate the bound. We give a geometric characterization of optimal pumps and show that they are noiseless and transport integral charge in a cycle. Finally we discuss an example of an optimal pump related to the Hall effect.
ABSTRACT
Camillo Golgi is well-known for his development of a staining technique that permitted profound contributions in histology. He is also well-known as the champion of a theory describing the organization of the nervous system as a reticular network. He shared the 1906 Nobel prize with Ramon y Cajal, who professed an antagonistic neuron theory which ultimately proved correct. We recently came across an original reprint of Golgi's work from an obscure reference. It deals with an important variation in the famous Golgi stain. In translating this original work into English, we present a piece of history, a comparison of Golgi's staining techniques, and a glimpse into Golgi's peculiar style and personality.
Subject(s)
Neurons/cytology , Staining and Labeling/methods , Animals , Cerebral Cortex/cytology , Histological Techniques/history , History, 19th Century , Italy , Pathology/history , Staining and Labeling/historyABSTRACT
Funduscopic examination of two young adults complaining of blurred vision revealed small symmetrical macular lesions suggestive of solar retinopathy. Although both patients had recently looked at the sun for less than one minute, it is common to look at the sun for longer periods (ie, sunsets) without incurring visual symptoms of retinal lesions. Our biophysical analysis revealed the important parameters of solar retinopathy and the minimum exposure to the sun that would produce such lesions. Under ideal optical conditions, solar retinopathy can occur following extremely short observations of the sun.
