Journal of quantitative spectroscopy and radiative transfer impact factor

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To achieve a particular US intensity at depth, account must be taken of the proportion of energy which has been absorbed by the tissues in the more superficial layers. The table gives an approximate reduction in energy levels with typical tissues at two commonly used frequencies, and more detailed information is found in the dose calculation materialAs the penetration (or transmission) of US is not the same in each tissue type, it is clear that some tissues are capable of greater absorption of US than others.

Generally, the tissues with the higher protein content will absorb US to a greater extent, thus tissues with high water content and low protein content absorb little of the US energy (e. Although cartilage and bone are at the upper end of this scale, the problems associated with wave reflection mean that the majority of US energy striking the surface of either of these tissues is likely to be reflected.

The application of aloe vera juice US to tissues with a low energy absorption capacity is less likely to be effective than the application of the energy into a more highly absorbing material.

Recent evidence of the ineffectiveness of such an intervention can be found in Wilkin et al. Most machines offer the facility for pulsed US journal of quantitative spectroscopy and radiative transfer impact factor, and for many clinicians, this is a preferable mode of treatment. Until recently, the pulse duration (the time during which the machine is on) was almost exclusively 2ms (2 thousandths of a second) with a variable off period.

Some machines now offer a variable on time though whether this is of clinical significance has yet to be determined. Typical pulse ratios are 1:1 and 1:4 though others are available (see dose calculations). In 1:1 mode, the machine offers an output for 2ms followed by 2ms rest. In 1:4 mode, the 2ms output is followed by an 8ms rest period. The adjacent diagram illustrates the effect of varying the pulse ratio. The effects of pulsed US are well documented and this type of output is preferable especially in the treatment of the more acute lesions.

Some machines offer pulse dc johnson that do not appear to be supported from the literature (e. The proportion of time that the machine is ON compared with OFF is a relevant journal of quantitative spectroscopy and radiative transfer impact factor in dosage calculations and further details are included in the dose calculation support material.

One of the therapeutic effects for which ultrasound has been used is in relation to tissue healing. The following information is intended to provide a summary of some of the essential research in this field together with some possible mechanisms through which US treatments may achieve these changes. It is not intended to be a complete explanation of these phenomena or a comprehensive review of the current literature.

It may, none the less, provide some useful basic information for clinical application. In thermal mode, US will be most effective in heating the dense collagenous tissues and will require a relatively high intensity, preferably in journal of quantitative spectroscopy and radiative transfer impact factor mode to achieve this effect. It is too simplistic to assume that with a particular treatment application there will either be thermal or non thermal effects.

It is almost inevitable that both will occur, but it is furthermore reasonable to argue that the dominant effect will be influenced by journal of quantitative spectroscopy and radiative transfer impact factor parameters, especially the mode of application i.

It can be used to selectively raise the temperature of particular tissues due to its mode of action. These bubbles then collapse very quickly releasing a large amount of energy which is detrimental to tissue viability. There is no evidence at present to suggest that this phenomenon occurs at therapeutic levels if a good technique is used. There are applications of US that deliberately employ the unstable cavitation effect (High Intensity Focused Ultrasound or HIFU) but it is beyond the remit of this summary.

Sodium ion permeability is altered resulting in changes journal of quantitative spectroscopy and radiative transfer impact factor the cell membrane potential. There is little, if any hard evidence for this often cited principle. The process of tissue repair is a complex series of cascaded, chemically mediated events that lead to the production of scar tissue that constitutes an effective material to restore the continuity of the damaged tissue. By increasing the activity of these cells, the overall influence of therapeutic US is certainly pro-inflammatory rather than anti-inflammatory.

The inflammatory response is essential to the effective repair of tissue, and the journal of quantitative spectroscopy and radiative transfer impact factor efficiently the process can complete, the more effectively the take the condom off can progress to the next phase (proliferation). A further benefit is that the inflammatory chemically mediated events are associated with stimulation of the next (proliferative) phase, and hence the promotion of the inflammatory phase also acts as a promoter of the proliferative phase.

Employed at an how to calculate body mass index treatment dose, with optimal treatment parameters (intensity, pulsing and time), the benefit of US is to make as efficient as possible to earliest repair phase, and thus have a promotional effect on the whole healing cascade. The role of ultrasound in this phase may also have the capacity to influence collagen fibre orientation as demonstrated in an elegant study by Byl et al.

It would appear that if a tissue is repairing in a compromised or inhibited fashion, the application of therapeutic ultrasound at an appropriate dose will enhance this activity. The effective application of ultrasound to zicam these aims is dose dependent.



26.04.2019 in 13:21 Зоя:
Это хорошая идея.

27.04.2019 in 01:01 lanfastvenberk79:
Привильное мнение но не все верно, вы упустили довольно много деталей, будьте впредь внимательнее