Linear probing

In fluorescence spectroscopy, the orientation distribution of the guest probe is not necessarily identical to the actual orientation of the polymer chains, even if it is added at very small concentrations (i.e., a probe with high fluorescence efficiency). As a matter of fact, it is generally assumed that long linear probes are parallel to the polymer main chain, but this is not necessarily the case. Nevertheless, if the relation between the distribution of the probe axes and those of the polymer axes is known, the ODF of the structural units can be calculated from that of the probe thanks to the Legendre s addition theorem. Finally, the added probe seems to be mainly located in the amorphous domains of the polymer [69] so that fluorescence spectroscopy provides information relative to the noncrystalline regions of the polymeric samples. 

Aloka Pro Sound SSD 4000 used for ultrasound examinations. For pregnancy confirmation, a 10 MHz linear probe (UST5542) is used. For fetal examinations, a 7.5 MHz probe (UST 5524) or 5 MHz convex probe (UST 992-5) is used depending on the size of the fetus. 

Figure 3. Calculated LF PADs for ionization of a model C v molecule. PADs are shown for ionization of a and aj symmetry orbitals for the same set of dynamical parameters. The molecular axis distribution in these calculations was described as a cos2 0 distribution, where 0 is the angle between the direction of linear polarization of the pump laser and the principal molecular axis. The linear probe polarization is along the z axis. Panel (a) shows PADs for parallel pump and probe polarizations, while panel (b) shows PADs for perpendicular pump and probe polarizations. See Ref. [55] for the dynamical parameters used in these calculations.

The design of hybridization formats that enable important changes (fluorescence intensity increase or wavelength shifts) in the presence of the targets is the focus of intense research because their use can simplify the analyses in vitro and provide the possibility of applications in living organisms. The most frequently used involve binary probes (35), competitive hybridization probes (18), linear probes with only one F (2, 5, 16, 29, 31), and molecular beacons (MBs) (39-41), (Fig. 3). 

Figure 3 Schematic representation of the main hybridization formats, (a) Binary probes, (b) Competitive hybridization probes, (c) Linear probe with one F. (d) Moiecuiar Beacon, (e) Aptamer.

Typically, a microdialysis probe consists of a small piece (2-10 mm) of a cylindrical dialysis membrane (the hollow fibre), connected to an inlet and an outlet tube of suitable dimensions. Despite the differences in design, what essentially typifies the probe is the position of the inlet and outlet tubes. Basically, two types of probes can be distinguished in the first one, the two tubes are positioned in a serial arrangement in the other type, the inlet and outlet tubes are concentric or parallel. Consequently, in the first type, which is normally termed a linear probe , the hollow fibre is glued in between. In the second one, it is affixed at the tip, and this is usually called a concentric probe . In addition to these two basic designs, other probes are available such as the loop probe , the shunt probe , and the flexible probe . Figure 12.1 shows some schematic representations of these probes. 

The linear probe is the simplest design and is the most adapted for sampling of soft tissues such as muscle [21,22], adipose and subcutaneous tissue [23-25], liver [26], and tumours [27,28-30]. The advantages of this kind of probe are the simplicity of construction, the small dimensions and hi flexibility (all of which minimize the tissue damage) and the ruggedness, which is sometimes achieved by inserting into the lumen of the hollow fibre... 

The loop probes are linear probes with a longer membrane (10-50 mm), often folded to form a loop. Their large surface area increases the amount of analyte retrieved by the probe and therefore they are a good choice for in vitro microdialysis and for sample cleanup. 

The shunt probe can be considered as a variation because the linear probe is contained inside another plastic tube (the shunt) where the fluid to be sampled passes, this arrangement allowing the continuous sampling from moving fluids. First described by Scott and Limte [31] it is usually appUed for bile sampling [32,33] but in vitro applications are also described such as that for milk analysis [34]. 

Eqs. (2) and (3) stand, respectively, for bilinear and linear probe-system coupling. For optical probes (2) and (3) correspond to Raman and single-photon scattering, respectively. For atom or neutron probes (2) is appropriate. 

Figure 2 Typical microdialysis probe geometries, (a) Rigid cannula probe typically used for implantation in the brain, (b) Flexible cannula probe for implantation in the blood vessel of a rat. (c) Linear probe designed for peripheral tissues such as skin, muscle, or liver, (d) Shunt or bypass probe is a linear probe inside a larger tube used for sampling the bile duct of the rat.

While a 3-4 MHz curved array scanner is used for routine screening for gastric cancers, detailed examination including the evaluation of wall stratification should be performed with a high-frequency (5-9 MHz) linear probe for its superior spatial resolution. Tissue harmonic imaging is also recommended to reduce noises such as side lobe artifacts (Laing and Kurtz 1982). 

Fig. 16.7. a Longitudinal scan of pyloric stenosis due to an advanced gastric cancer. Diffuse wall thickening of the antrum is demonstrated, b Close-up view of the posterior wall of the antrum with a 7-MHz linear probe. Wall stratification has not been completely destroyed, c Endoscopy reveals marked luminal narrowing... 

Fig. 19.3. a Endoscopy of a gastric cyst. The lesion is located in the anterior wall of the antrum and is covered with normal mucosa without indentation or erosion, b Sonography with a convex probe (3 MHz) of the gastric cyst (gc). A small ane-choic lesion is demonstrated, although the main layer where it lies is not clear, c Scanning with a high-frequency linear probe (7 MHz) revealed that the lesion (gc) lies in the submucosal layer (sml). S stomach... 

The anterior urethra can be explored using high frequency linear probes that are able to examine the penile and perineal tract and the structures of the surrounding corpus spongiosum (Gluck et al. 1988 Nash et al. 1995). This exam consists of scanning performed after a saline solution is introduced... 

Figure 12 Typical microdialysis probes for various tissues of rats or similar-size animals. (A) intracerebral guide cannula and rigid concentric cannula probe for brain tissue, (B) linear probe used for sampling peripheral tissues such as liver, muscle, dermis, tumor, kidney, (C) vascular probe for sampling from the jugular vein, and (D) shunt probe for sampling from the bile duct. Unlabeled arrows indicate direction of dialysate flow into and out of probes. (Courtesy of Bioanalytical Systems Inc.)...

We remark that deletion from a linear-probing hash table requires some care if done naively, entries can get lost (Ref. 198, pp. 526-7). However, these subtleties are irrelevant if deletions always occur in a last-in-first-out manner (as in the slithering-tortoise algorithm), or occur only when cleaning up the table at the end (as in the pivot and cut-and-paste algorithms). In the latter case it suffices to keep a linear hst of the memory locations in which elements have been inserted these locations can then be cleared at the end. 

At fixed c, pi(c, M) decreases markedly with increasing matrix M. Figure 3.9 shows that probe topology has almost no effect on fi. At all c and M studied, the pc of the linear probes is very nearly equal to pi of the star probes. Saha, et al. conclude that the migration mechanisms for their linear and star DNA do not change between c < c and o c. Saha, et a/. (12) fiorther propose that the M-dependence of pi shows that their DNA probes do not reptate instead, they drag matrix chains with them. 

Wang and co-workers modified their linear probe design with an oblique incident source fibre and... 

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