Quad-images

In practice this may not be achieved perfectly, so weak quad images may be produced. They can be readily recognized as they show different phases than the rest of the spectrum. 

By convention a pure absorption signal using the quadrature detection procedure is composed of a real part Ik,y and a imaginary part Ik,x- Conversion to spherical operators means that i Ik, i = (Ik,y + i Ik,xV 2 represents a pure absorption signal, while Ik,+i represents a pure dispersion signal. The operator Ik,+i corresponds to the "quad image". 

Fig. 1. Quadrupole mass analyzer. Reproduced from http //www.chm.bris.ac.ulc/ms/images/quad-schematic. gif, with permission from Dr Paul Gates, School of Chemistry, University of Bristol, UK.

Descriptions of the simplest data structure entities and explanations of their nature follow in succeeding sections. Basic data structures are stack, queue, and other linear lists multiple-dimension arrays (recursive) lists and trees (including forests and binary trees). Pointer or link simply means computer data constituting a memory location. Level indicates position in a structure that is hierarchical. Link, level, and the elementary structures are almost intuitive concepts. They are fairly easily understood by reference to their names or to real-life situations to which they relate. Evolving computer practice has had two effects. First, the impact of the World Wide Web and Internet browsers has acquainted many computer users with two basic ideas link (pointer) and level. Second, computer specialists have increased their use of advanced data structures. These may be understandable from their names or descriptive properties. Some of these terms are tries, quad-trees (quadtrees, quaternary trees), leftist-trees, 2-3 trees, binary search trees, and heap. While they are less common data structures and unlikely to be part of a first course in the field, they enable algorithmic procedures in applications such as image transmission, geographic data, and library search. 

Oto A, Ernst R, Shah R et al (2005) Right-lower-quad-rant pain and suspected appendicitis in pregnant women evaluation with MR imaging - initial experience. Radiology 234 445-451... 

Fig. 6.6 General scheme of the IIF attached to the LnAMS a the infrared image fiimace (IIF) at atmospheric pressure, showing the IR lamp unit (1) and position of the sample holder (2), b the interface, which has a concentric quartz tube with a 70 pm orifice at its center (3) and exit stainless steel tube (4), both of which are fixed to the flange of the gate valve (5), c the reaction (ionization) chamber at the pressure of 100 Pa, with the Li ion emitter (30 V) bead fused onto the Ir wire (6), electrode (40 V) (7), and electrostatic lens (0,-150, 0 V, respectively) (8), d the envelope for quad-rupole MS (9). (Reprinted with permission from Ref [27]. 2009, American Chemical Society)...

Near-IR images of IC 342 in the J, H and K bands were taken on the 1.3m at Kitt Peak National Observatory (KPNO) using the Simultaneous Quad Infrared Imaging Detector (SQIID) on the night of October 26, 1992. The SQIID uses cold dichroic beam splitters to simultaneously image J, H, K and L onto Hughes 256x256 hybrid PtSi Schottky barrier diode arrays. 

---