METHOD AND APPARATUS FOR ASSESSING PERIPHERAL ARTERIAL TONE

Abstract

A computer-implemented method for assessing peripheral arterial tone (100), PAT, of an individual (1) monitored by optical plethysmography and for detecting therefrom occurrence of a sleep-related event, comprising:—obtaining: o an optical plethysmography signal (101) measured at an investigated volume (11); and o light intensities (102;103) acquired at two or more points in time (12;13) along said optical plethysmography signal (101);—determining changes in arterial blood volume (16) in said investigated volume (11) between said two or more points in time (12;13) by determining a logarithm (17) or a function approximation thereof (17) of a function of said light intensities (102;103), thereby assessing PAT (100) of said individual (1); and—determining a drop in said PAT (100) indicative for a vasoconstriction of arteries and arterioles in said investigated volume (11), thereby detecting occurrence of a sleep-related event.

Claims

1. A computer-implemented method for assessing peripheral arterial tone (100), PAT, of an individual (1) monitored by optical plethysmography and for detecting therefrom occurrence of a sleep-related event at said individual (1), wherein said method comprises the steps of: obtaining: an optical plethysmography signal (101) measured at an investigated volume (11) of said individual (1); and light intensities (102;103) acquired by optical plethysmography at two or more points in time (12;13) along said optical plethysmography signal (101); determining changes in arterial blood volume (16) in said investigated volume (11) between said two or more points in time (12;13) by determining a logarithm (17) or a function approximation thereof (17) of a function of said light intensities (102;103), thereby assessing PAT (100) of said individual (1); and determining a drop in said PAT (100) indicative for a vasoconstriction of arteries and arterioles in said investigated volume (11), thereby detecting occurrence of a sleep-related event at said individual (1).

2. The method according to claim 1, wherein said function of said light intensities (102;103) corresponds to a ratio of said light intensities (102;103).

3. The method according to claim 1 or 2, wherein said evaluation function (17) corresponds to a logarithm of a ratio of said light intensities (102;103); and wherein said evaluation function (17) depends on one or more of the following: an optical path length; a function of said oxygen saturation estimate (104); said changes in arterial blood volume (16) in said investigated volume (11).

4. The method according to any of the preceding claims, wherein at least one (12) of said points in time (12;13) corresponds to the diastole in a cardiac cycle of said individual (1) and/or wherein at least one (13) of said points in time (12;13) corresponds to the systole in a cardiac cycle of said individual (1).

5. The method according to any of the preceding claims, wherein said method further comprises the steps of: providing a light source (2) configured to emit light (40) at a wavelength; providing a sensor (4); collecting, by optical plethysmography and on said sensor (4), propagated light (41) corresponding to light (40) at said wavelength being transmitted or reflected when propagating in said investigated volume (11) of said individual (1) at said two or more points in time (12;13); and determining said light intensities (102;103) of said propagated light on said sensor (4) at said two or more points in time (12;13).

6. An apparatus (10) comprising at least one processor and at least one memory (6) including computer program code, the at least one memory (6) and computer program code configured to, with the at least one processor, cause the apparatus (10) to perform: obtaining: an optical plethysmography signal (101) measured at an investigated volume (11) of said individual (1); and light intensities (102;103) acquired by optical plethysmography at two or more points in time (12;13) along said optical plethysmography signal (101); determining changes in arterial blood volume (16) in said investigated volume (11) between said two or more points in time (12;13) by determining a logarithm (17) or a function approximation thereof (17) of a function of said light intensities (102;103), thereby assessing PAT (100) of said individual (1); and determining a drop in said PAT (100) indicative for a vasoconstriction of arteries and arterioles in said investigated volume (11), thereby detecting occurrence of a sleep-related event at said individual (1).

7. A system (20) comprising an apparatus according to claim 6, and further comprising: a light source (2;3) configured to emit light; and a sensor (4) configured to collect by optical plethysmography propagated light corresponding to said light being transmitted or reflected when propagating in said investigated volume (11) of said individual (1) at said two or more points in time (12;13); and further configured to determine said light intensities (102;103) of said propagated light at said two or more points in time (12;13).

8. A computer program product comprising computer-executable instructions for causing a system to perform at least the following: obtaining: an optical plethysmography signal (101) measured at an investigated volume (11) of said individual (1); and light intensities (102;103) acquired by optical plethysmography at two or more points in time (12;13) along said optical plethysmography signal (101); determining changes in arterial blood volume (16) in said investigated volume (11) between said two or more points in time (12;13) by determining a logarithm or a function approximation thereof (17) of a function of said light intensities (102;103), thereby assessing PAT (100) of said individual (1); and determining a drop in said PAT (100) indicative for a vasoconstriction of arteries and arterioles in said investigated volume (11), thereby detecting occurrence of a sleep-related event at said individual (1).

9. A computer readable storage medium comprising computer-executable instructions for performing the following steps when the program is run on a computer: obtaining: an optical plethysmography signal (101) measured at an investigated volume (11) of said individual (1); and light intensities (102;103) acquired by optical plethysmography at two or more points in time (12;13) along said optical plethysmography signal (101); determining changes in arterial blood volume (16) in said investigated volume (11) between said two or more points in time (12;13) by determining a logarithm (17) or a function approximation thereof (17) of a function of said light intensities (102;103), thereby assessing PAT (100) of said individual (1); and determining a drop in said PAT (100) indicative for a vasoconstriction of arteries and arterioles in said investigated volume (11), thereby detecting occurrence of a sleep-related event at said individual (1).

10. Use of a logarithm or a function approximation thereof (17) for assessing peripheral arterial tone (100), PAT, of an individual (1) monitored by optical plethysmography and for detecting therefrom occurrence of a sleep-related event at said individual (1), wherein said assessing peripheral arterial tone (100) comprises: obtaining: an optical plethysmography signal (101) measured at an investigated volume (11) of said individual (1); and light intensities (102;103) acquired by optical plethysmography at two or more points in time (12;13) along said optical plethysmography signal (101); determining changes in arterial blood volume (16) in said investigated volume (11) between said two or more points in time (12;13) by determining a logarithm (17) or a function approximation thereof (17) of a function of said light intensities (102;103), thereby assessing PAT (100) of said individual (1); and determining a drop in said PAT (100) indicative for a vasoconstriction of arteries and arterioles in said investigated volume (11), thereby detecting occurrence of a sleep-related event at said individual (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Some example embodiments will now be described with reference to the accompanying drawings.

[0104] FIG. 1 depicts an example embodiment of an apparatus according to the present disclosure.

[0105] FIG. 2 depicts an example embodiment of a system according to the present disclosure comprising an apparatus according to the present disclosure.

[0106] FIG. 3 depicts an example embodiment of a system according to the present disclosure comprising an apparatus according to the present disclosure.

[0107] FIG. 4 depicts an example embodiment of a comparison of a PAT measurement of an individual assessed by an apparatus according to the present disclosure and assessed without determining a logarithm of a function of the light intensities.

[0108] FIG. 5 depicts an example embodiment of a computer-implemented method according to the present disclosure.

[0109] FIG. 6 shows an example embodiment of a suitable computing system for performing one or several steps in embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENT(S)

[0110] FIG. 1 illustrates an example embodiment of an apparatus 10 according to the present disclosure. The apparatus 10 comprises at least one memory 6, at least one processor, wherein the memory 6 includes computer program code configured to, with the at least one processor, cause the apparatus 10 to perform the following: [0111] obtain: [0112] an optical plethysmography signal 101 measured at an investigated volume of an individual; and [0113] light intensities 102;103 acquired by optical plethysmography at two or more points in time 12;13 along the optical plethysmography signal 101, wherein the light intensity 102 is respectively acquired at the point in time 12 and wherein the light intensity 103 is respectively acquired at the point in time 13; [0114] determining changes in arterial blood volume 16 in the investigated volume between the two or more points in time 12;13 by determining a logarithm 17 or a function approximation thereof 17 of a function of the light intensities 102;103, thereby assessing PAT 100 of the individual; and [0115] determining a drop in the PAT 100 indicative for a vasoconstriction of arteries and arterioles in the investigated volume 11, thereby detecting occurrence of a sleep-related event at the individual 1.

[0116] The apparatus 10 obtains the optical plethysmography signal 101 and/or the light intensities 102;103 from an external device. According to an alternative embodiment, the apparatus 10 obtains the optical plethysmography signal 101 and/or the light intensities 102;103 from the memory 6. According to a further alternative embodiment, the apparatus 10 the optical plethysmography signal 101 and/or the light intensities 102;103 from the memory 6 and/or from an external device. Optionally, at least one point in time 12 corresponds to the diastole of a cardiac cycle of the individual and/or at least one point in time 13 corresponds to the systole of a cardiac cycle of the individual. The apparatus 10 is configured to determine an evaluation function 17 which corresponds to a logarithm 17 or a function approximation thereof 17 of a function of the light intensities 102;103. The evaluation function 17 depends on one or more of the following: an optical path length, a function of the oxygen saturation estimate, a change in arterial blood volume in the investigated volume.

[0117] FIG. 2 illustrates an example embodiment of a system 20 according to the present disclosure. Components having identical reference numbers to numbers on FIG. 1 perform the same function. The system 20 of FIG. 2 comprises an apparatus 10 according to the present disclosure. Optionally, the system 20 further comprises a light source 2 and a sensor 4. A light source 2 is configured to emit light 40. The apparatus 10 is configured to: [0118] obtain: [0119] an optical plethysmography signal 101 measured at an investigated volume 11 of an individual; and [0120] light intensities 102;103 acquired by optical plethysmography at two or more points in time 12;13 along the optical plethysmography signal 101, wherein the light intensity 102 is respectively acquired at the point in time 12 and wherein the light intensity 103 is respectively acquired at the point in time 13; [0121] determining changes in arterial blood volume 16 in the investigated volume 11 between the two or more points in time 12;13 by determining a logarithm 17 or a function approximation thereof 17 of a function of the light intensities 102;103, thereby assessing PAT 100 of the individual 1; and [0122] determining a drop in the PAT 100 indicative for a vasoconstriction of arteries and arterioles in the investigated volume 11, thereby detecting occurrence of a sleep-related event at the individual 1.

[0123] The apparatus 10 obtains the optical plethysmography signal 101 and/or the light intensities 102;103 from an external device from an external device 200 comprising at least one light source 2 and/or the sensor 4. For example, the external device 200 determines the arterial blood volume pulse in the investigated volume 11 of the individual 1. The external device 200 comprises a battery for powering the different electrical components 2;4. The light source 2 is configured to emit light, i.e. to transmit the light 40 into the investigated volume 11 of the individual attached to the external device 200, for example into the finger 11 of the individual 1 as illustrated, more particularly to a distal end 11 of a finger of the individual. The external device 200 further comprises control circuitry for controlling the light source 2, i.e., for enabling or disabling the light source 2 and for receiving the measurements for example of the light intensities from the sensor 4. Control circuitry may further comprise a memory component for temporarily storing the obtained measurements. Control circuitry is further coupled to a wireless interfacing circuitry 50 and configured to forward the measurements to the wireless interfacing circuitry 50. Wireless interface 50 may support a short range and/or low power wireless communication protocol for efficient transmission of the measurements to a receiving part of the system. Wireless interface 50 may for example operate according to the Bluetooth Low Energy, BLE, protocol as defined by the Bluetooth Special Interest Group or according to a Near Field Communication, NFC, protocol. Operation by such protocols together with forwarding of the raw optical plethysmography signal 101 allows miniaturization of the external device 200 such that it fits on a finger or a nostril and allows operation during multiple nights According to an alternative embodiment, the apparatus 10 obtains the optical plethysmography signal 101 and/or the light intensities 102;103 from the memory 6. According to a further alternative embodiment, the apparatus 10 the optical plethysmography signal 101 and/or the light intensities 102;103 from the memory 6 and/or from an external device. Optionally, at least one point in time 12 corresponds to the diastole of a cardiac cycle of the individual and/or at least one point in time 13 corresponds to the systole of a cardiac cycle of the individual. The apparatus 10 is configured to determine an evaluation function 17 which is a function of the light intensities 102;103. The external device 200 collects, by optical plethysmography on the sensor 4, propagated light 41 corresponding to light 40 emitted by the light source 2, wherein the light 40 is transmitted or reflected by the investigated volume 11 when propagating in the distal end of the digit of the individual 1 at the two or more points in time 12;13 along the optical plethysmography signal 101. In other words, the external device 200 collects, by optical plethysmography on the sensor 4, a light intensity 102 corresponding to propagated light 41 corresponding to light 40 emitted by the light source 2, wherein the light 40 is transmitted or reflected by the investigated volume 11 when propagating in the distal end of the digit of the individual 1 and is collected on the sensor 4 at a first point in time 12; and the external device 200 collects, by optical plethysmography on the sensor 4, a light intensity 103 corresponding to propagated light 41 corresponding to light 40 emitted by the same light source 2, wherein the light 40 is transmitted or reflected by the investigated volume 11 when propagating in the distal end of the digit of the individual 1 and is collected on the sensor 4 at a second point in time 13. The apparatus then determines an evaluation function 17. The evaluation function 17 for example corresponds to a logarithm of a function of the light intensities 102;103. The evaluation function 17 for example corresponds to a logarithm of a ratio of the light intensities 102;103. The evaluation function 17 depends on one or more of the following: an optical path length, a function of the oxygen saturation estimate, a change in arterial blood volume in the investigated volume.

[0124] FIG. 3 illustrates an example embodiment of a system 20 according to the present disclosure. Components having identical reference numbers to numbers on FIG. 1 or FIG. 2 perform the same function. The system 20 of FIG. 3 comprises an apparatus 10 according to the present disclosure. Optionally, the system 20 further comprises at least one light source 2 and a sensor 4, comprised in the apparatus 10. A light source 2 is configured to emit light 40. The apparatus 10 is configured to: [0125] obtain: [0126] an optical plethysmography signal 101 measured at an investigated volume 11 of an individual; and [0127] light intensities 102;103 acquired by optical plethysmography at two or more points in time 12;13 along the optical plethysmography signal 101, wherein the light intensity 102 is respectively acquired at the point in time 12 and wherein the light intensity 103 is respectively acquired at the point in time 13; [0128] determining changes in arterial blood volume 16 in the investigated volume 11 between the two or more points in time 12;13 by determining a logarithm 17 or a function approximation thereof 17 of a function of the light intensities 102;103, thereby assessing PAT 100 of the individual 1; and [0129] determining a drop in the PAT 100 indicative for a vasoconstriction of arteries and arterioles in the investigated volume 11, thereby detecting occurrence of a sleep-related event at the individual 1.

[0130] The apparatus 10 obtains the optical plethysmography signal 101 and/or the light intensities 102;103 from the light source 2 and/or the sensor 4. For example, the apparatus 10 determines the arterial blood volume pulse in the investigated volume 11 of the individual 1. The apparatus 10 comprises a battery for powering the different electrical components 2;3;4. The light source 2 is configured to emit light, i.e. to transmit the light 40 into the investigated volume 11 of the individual attached to the apparatus 10, for example into the finger 11 of the individual 1 as illustrated, more particularly to a distal end 11 of a finger of the individual as illustrated. The apparatus 10 further comprises control circuitry for controlling the light source 2, i.e., for enabling or disabling the light source 2 and for receiving the measured arterial blood volume pulse values from the sensor 4. Control circuitry may further comprise a memory component for temporarily storing the obtained measurements. Control circuitry is further coupled to a wireless interfacing circuitry 50 and configured to forward the measurements to the wireless interfacing circuitry 50. Wireless interface 50 may support a short range and/or low power wireless communication protocol for efficient transmission of the measurements to a receiving part of the system. Wireless interface 50 may for example operate according to the Bluetooth Low Energy, BLE, protocol as defined by the Bluetooth Special Interest Group or according to a Near Field Communication, NFC, protocol. Operation by such protocols together with forwarding of the raw optical plethysmography signal 101 allows miniaturization of the apparatus 10 such that it fits on a finger or a nostril and allows operation during multiple nights. According to an alternative embodiment, the apparatus 10 obtains one or more of the optical plethysmography signal 101, the light intensities 102;103 from the memory 6. According to a further alternative embodiment, the apparatus 10 obtains one or more of the optical plethysmography signal 101, the light intensities 102;103 from the light source 2 and/or the sensor 4 and/or from the memory 6. Optionally, at least one point in time 12 corresponds to the diastole of a cardiac cycle of the individual and/or at least one point in time 13 corresponds to the systole of a cardiac cycle of the individual. The apparatus 10 is configured to determine an evaluation function 17 which is a function of the light intensities 102;103. The apparatus 10 collects, by optical plethysmography on the sensor 4, propagated light 41 corresponding to light 40 emitted by the light source 2, wherein the light 40 is transmitted or reflected by the investigated volume 11 when propagating in the distal end of the digit of the individual at the two or more points in time 12;13 along the optical plethysmography signal 101. In other words, the apparatus 10 collects, by optical plethysmography on the sensor 4, a light intensity 102 corresponding to propagated light 41 corresponding to light 40 emitted by the light source 2, wherein the light 40 is transmitted or reflected by the investigated volume 11 when propagating in the distal end of the digit of the individual 1 and is collected on the sensor 4 at a first point in time 12; and the apparatus 10 collects, by optical plethysmography on the sensor 4, a light intensity 103 corresponding to propagated light 41 corresponding to light 40 emitted by the same light source 2, wherein the light 40 is transmitted or reflected by the investigated volume 11 when propagating in the distal end of the digit of the individual 1 and is collected on the sensor 4 at a second point in time 13. The apparatus then determines an evaluation function 17. The evaluation function 17 for example corresponds to a logarithm of a function of the light intensities 102;103. The evaluation function 17 for example corresponds to a logarithm of a ratio of the light intensities 102;103. The evaluation function 17 depends on one or more of the following: an optical path length, a function of the oxygen saturation estimate, a change in arterial blood volume in the investigated volume.

[0131] FIG. 4 illustrates an example comparison between PPG-amplitude-based peripheral arterial tone 401 both in function of time 60 of an individual, wherein the PPG-amplitude-based peripheral arterial tone 401 is assessed by considering changes in amplitude of pulses in an optical plethysmography signal as described in the prior art, and evaluation-function-based peripheral arterial tone 402 in function of time 60 of the same individual, wherein the evaluation-function-based peripheral arterial tone 402 is determined by the computer-implemented method according to the present disclosure, or by the apparatus according to the present disclosure, i.e. wherein the evaluation-function-based peripheral arterial tone 402 is assessed by determining a logarithm of a ratio of light intensities measured from an optical plethysmography signal. For clarity reasons, the evaluation-function-based peripheral arterial tone 402 is plotted by calculating

[00012]$\ln \left(\frac{I_h}{I_l}\right).$

According to an alternative embodiment, the evaluation-function-based peripheral arterial tone 402 is plotted by calculating

[00013]$\ln \left(\frac{I_l}{I_h}\right).$

As can be seen on FIG. 4, the PPG-amplitude-based peripheral arterial tone 401 and the evaluation-function-based peripheral arterial tone 402 evolve in a similar manner as a function of time 60 at a pre-vasoconstriction-event baseline value. But during the time periods 61 and 62, i.e. during occurrence of an event such as for example a sleep-related event, such as for example a sleep related respiratory event, it can be seen on FIG. 4 that the PPG-amplitude-based peripheral arterial tone 401 and the evaluation-function-based peripheral arterial tone 402 evolve in a similar manner but do not overlap anymore in the corresponding time periods 61 and 62. Indeed, in period 61, the PPG-amplitude-based peripheral arterial tone 401 drops to a level 403 which value is higher than the one of the level 404 to which the evaluation-function-based peripheral arterial tone 402 drops. Similarly, in period 62, the PPG-amplitude-based peripheral arterial tone 401 drops to a level 405 which value is higher than the one of the level 406 to which the evaluation-function-based peripheral arterial tone 402 drops. It can be seen on FIG. 4 that assessing peripheral arterial tone 100 by determining a logarithm of a function of light intensities acquired by optical plethysmography allows to detect the event occurring more accurately. Indeed, a drop in peripheral arterial tone 100 is indicative for a vasoconstriction of the arteries and the arterioles in the investigated volume under monitoring. This vasoconstriction can be related to the occurrence of an event at the individual under monitoring such as for example a sleep-related event, such as for example sleep apnea. As it can be seen on FIG. 4, the drop in the PPG-amplitude-based peripheral arterial tone 401 between the pre-vasoconstriction-event baseline value and the lowest point of the PPG-amplitude-based peripheral arterial tone 401 is smaller than the drop in the evaluation-function-based peripheral arterial tone 402 between the pre-vasoconstriction-event baseline value and the lowest point of the evaluation-function-based peripheral arterial tone 402. For example, a predetermined threshold value 407 for peripheral arterial tone 100 can be used to detect whether an event is occurring at the individual under monitoring such as for example a sleep-related event, such as for example sleep apnea: when the peripheral arterial tone 100 is above this predetermined threshold value 407, no event is detected, but when the peripheral arterial tone 100 is below this predetermined threshold value 407, an event is detected. The drop in the PPG-amplitude-based peripheral arterial tone 401 between the pre-vasoconstriction-event baseline value and the lowest point of the PPG-amplitude-based peripheral arterial tone 401 is such that the PPG-amplitude-based peripheral arterial tone 401 stays above the predetermined threshold value 407, which results in the absence of detection of an event occurring at the individual under monitoring such as for example a sleep-related event, such as for example sleep apnea. On the other hand, the drop in the evaluation-function-based peripheral arterial tone 402 between the pre-vasoconstriction-event baseline value and the lowest point of the evaluation-function-based peripheral arterial tone 402 is such that the evaluation-function-based peripheral arterial tone 402 drops below the predetermined threshold value 407, which results in the detection of an event occurring at the individual under monitoring such as for example a sleep-related event, such as for example sleep apnea. It can therefore be seen that assessing peripheral arterial tone 100 by determining a logarithm of a function of light intensities acquired by optical plethysmography allows to more accurately and more robustly detect the occurrence of an event occurring at the individual under monitoring such as for example a sleep-related event, such as for example sleep apnea.

[0132] FIG. 5 illustrates an example embodiment of a computer-implemented method for assessing peripheral arterial tone, PAT, of an individual monitored by optical plethysmography, wherein said method comprises the steps of: [0133] in a first step 501, obtaining: [0134] an optical plethysmography signal 101 measured at an investigated volume 11 of the individual 1; and [0135] light intensities 102;103 acquired by optical plethysmography at two or more points in time 12;13 along the optical plethysmography signal 101; and [0136] in a second step 502 consecutive to the first step 501, determining changes in arterial blood volume 16 in the investigated volume 11 between the two or more points in time 12;13 by determining a logarithm 17 or a function approximation thereof 17 of a function of the light intensities 102;103, thereby assessing PAT 100 of the individual 1; and [0137] in a third step 503 consecutive to the second step 502, determining a drop in the PAT 100 indicative for a vasoconstriction of arteries and arterioles in the investigated volume 11, thereby detecting occurrence of a sleep-related event at the individual 1.

[0138] FIG. 6 shows a suitable computing system 800 enabling to implement embodiments of the system. Computing system 800 may in general be formed as a suitable general-purpose computer and comprise a bus 810, a processor 802, a local memory 804, one or more optional input interfaces 814, one or more optional output interfaces 816, a communication interface 812, a storage element interface 806, and one or more storage elements 808. Bus 810 may comprise one or more conductors that permit communication among the components of the computing system 800. Processor 802 may include any type of conventional processor or microprocessor that interprets and executes programming instructions. Local memory 804 may include a random-access memory (RAM) or another type of dynamic storage device that stores information and instructions for execution by processor 802 and/or a read only memory (ROM) or another type of static storage device that stores static information and instructions for use by processor 802. Input interface 814 may comprise one or more conventional mechanisms that permit an operator or user to input information to the computing device 800, such as a keyboard 820, a mouse 830, a pen, voice recognition and/or biometric mechanisms, a camera, etc. Output interface 816 may comprise one or more conventional mechanisms that output information to the operator or user, such as a display 840, etc. Communication interface 812 may comprise any transceiver-like mechanism such as for example one or more Ethernet interfaces that enables computing system 800 to communicate with other devices and/or systems, for example with other computing devices 881, 882, 883. The communication interface 812 of computing system 800 may be connected to such another computing system by means of a local area network (LAN) or a wide area network (WAN) such as for example the internet. Storage element interface 806 may comprise a storage interface such as for example a Serial Advanced Technology Attachment (SATA) interface or a Small Computer System Interface (SCSI) for connecting bus 810 to one or more storage elements 808, such as one or more local disks, for example SATA disk drives, and control the reading and writing of data to and/or from these storage elements 808. Although the storage element(s) 808 above is/are described as a local disk, in general any other suitable computer-readable media such as a removable magnetic disk, optical storage media such as a CD or DVD, -ROM disk, solid state drives, flash memory cards, . . . could be used. Computing system 800 could thus correspond to the apparatus 10 in the embodiment illustrated by FIG. 1 or 2 or 3.

[0139] As used in this application, the term “circuitry” may refer to one or more or all of the following: [0140] (a) hardware-only circuit implementations such as implementations in only analog and/or digital circuitry and [0141] (b) combinations of hardware circuits and software, such as (as applicable): [0142] (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and [0143] (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and [0144] (c) hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation.

[0145] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0146] Although the present invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied with various changes and modifications without departing from the scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the scope of the claims are therefore intended to be embraced therein.

[0147] It will furthermore be understood by the reader of this patent application that the words “comprising” or “comprise” do not exclude other elements or steps, that the words “a” or “an” do not exclude a plurality, and that a single element, such as a computer system, a processor, or another integrated unit may fulfil the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned. The terms “first”, “second”, third”, “a”, “b”, “c”, and the like, when used in the description or in the claims are introduced to distinguish between similar elements or steps and are not necessarily describing a sequential or chronological order. Similarly, the terms “top”, “bottom”, “over”, “under”, and the like are introduced for descriptive purposes and not necessarily to denote relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the invention are capable of operating according to the present invention in other sequences, or in orientations different from the one(s) described or illustrated above.