Single-pixel detection approaches have been applied with success in different imaging
techniques such as optical microscopy. Here we show that it is possible to improve the resolution of
single-pixel microscopy by using an array of photodetectors and Fourier ptychography algorithms.
Laser-induced breakdown spectroscopy (LIBS) is applied to investigate the effect of diabetes mellitus (DM) on the elemental composition of fingernails. Measurements are carried out on 85 fingernail clippings including 51 diabetic and 34 control subjects. An auto-focus system has been designed and used in experiments to improve the repeatability of LIBS measurements. Classification of diabetic and nondiabetic subjects is examined using discriminant function analysis (DFA) method. This classification is based on 82 atomic, ionic, and molecular emission lines belonging to 13 elements as well as one molecule of fingernails. Emission lines that can be used as the best predictors are identified. The possibility of using this method for screening purposes is discussed based on the classification results. This preliminary work shows the ability of LIBS of fingernails in discrimination of DM patients and nondiabetic subjects using DFA method and its feasibility in screening purposes.
Laser-induced breakdown spectroscopy (LIBS) is applied to analyze human fingernails using nanosecond laser pulses. Measurements on 45 nail samples are carried out and 14 key species are identified. The elements detected with the present system are: Al, C, Ca, Fe, H, K, Mg, N, Na, O, Si, Sr, Ti as well as CN molecule. Sixty three emission lines have been identified in the spectrum that are dominated by calcium lines. A discriminant function analysis is used to discriminate among different genders and age groups. This analysis demonstrates efficient discrimination among these groups. The mean concentration of each element is compared between different groups. Correlation between concentrations of elements in fingernails is calculated. A strong correlation is found between sodium and potassium while calcium and magnesium levels are inversely correlated. A case report on high levels of sodium and potassium in patients with hyperthyroidism is presented. It is shown that LIBS could be a promising technique for the analysis of nails and therefore identification of health problems.
Radio frequency capacitive discharges (RFCD) in the frequency range 1-200 MHz are widely used for gas lasers pumping. Magnetic field has an efficient effect on many plasma processes. When we apply a uniform magnetic field to a rf excited plasma, the electron mobility in direction perpendicular to the magnetic field is reduced. The reduction in the electron mobility leads to a decrease in drift velocity of electrons. In rf excited gas discharges thickness of sheaths is equal to amplitude of electron drift oscillations. So the reduction in the drift velocity of electrons leads to reduction in thickness of sheaths. As we know, small signal gain of active medium in rf excited CO<sub>2</sub> lasers in bulk plasma region is much more than that in sheaths. Thus it can be concluded that applying magnetic field to rf excited CO<sub>2</sub> lasers leads to an enhancement in thickness of positive column and output power. Experimental results show an external magnetic field leads to an increase in output power of rf excited CO<sub>2</sub> lasers. Furthermore, in this paper we use a one dimensional model to show external magnetic field effects on some discharge parameters such as V-I characteristics, intensity of emitted light from plasma, impedance of sheaths and positive column of plasma for mixture of 10% CU<sub>2</sub>, 10% N<sub>2</sub> and 80% He at pressure of 100 mbar theoretically.