Hospitals, clinics, and other types of healthcare facilities are equipped with nurse call systems that utilize various devices located throughout the hospital. The nurse call systems enable patients and/or nurses to communicate over a network with one or more nurse stations. The nurse call system helps in organizing hospital resources and facilitating communication in the hospital environment so as to enhance patient safety and improve staff efficiency. Pullcord stations may be engineered to work with nurse call systems, allowing a call to be placed to the nurse call system by pulling a cord on the pullcord station. Pullcord stations are effective in enhancing the quality and care of a patient since a patient can place a priority call with a simple act.
Embodiments of the disclosure provide a waterproof pullcord station for management of patient care, the pullcord station includes a cord, a face plate assembly, and a wall plate assembly. The face plate assembly includes a cord retainer coupled to the cord, and an actuator post coupled to the cord retainer. The wall plate assembly includes a wall plate comprising a frontside and a backside, wherein the frontside comprises a single material and the backside comprises an opening, the wall plate serving as a housing for an electronic circuit. The wall plate assembly further includes the electronic circuit wirelessly coupled to the actuator post and configured to determine whether the cord has been pulled by monitoring the wireless coupling between the actuator post and the electronic circuit. The wall plate assembly further includes a back cap configured to interface with the opening of the backside. The face plate assembly is coupled to the wall plate assembly.
Embodiments of the disclosure further provide a system for management of patient care. The system includes a nurse call server comprising a processor and a non-transitory computer readable medium; and a waterproof pullcord station. The waterproof pullcord station includes a cord, a face plate assembly, and a wall plate assembly coupled to the faceplate assembly. The face plate assembly includes a cord retainer coupled to the cord, and an actuator post coupled to the cord retainer. The wall plate assembly includes: a wall plate comprising a frontside and a backside, wherein the frontside comprises a single material and the backside comprises an opening, the wall plate serving as a housing for an electronic circuit. The wallplate assembly further includes the electronic circuit wirelessly coupled to the actuator post and configured to determine whether the cord has been pulled by monitoring the wireless coupling between the actuator post and the electronic circuit. The wall plate assembly further includes a back cap configured to interface with the opening of the backside. The waterproof pullcord station initiates a call to the nurse call server when the cord has been pulled.
Embodiments of the disclosure further provide a waterproof pullcord station. The pullcord station includes a cord, a face plate assembly, and a wall plate assembly coupled to the face plate assembly. The face plate assembly includes a cord retainer coupled to the cord, and an actuator post coupled to the cord retainer. The wall plate assembly includes a wall plate comprising a frontside and a backside, wherein the frontside comprises a single material and the backside comprises an opening. The wall plate assembly further includes a back cap configured to interface with the opening of the backside to seal the backside creating an interior cavity with the backside; wherein the face plate assembly is configured to allow excess liquid to drain from the pullcord station, and the wall plate assembly is configured to prevent ingress of water in the interior cavity.
The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. All features described and/or illustrated herein can be used alone or combined in different combinations in embodiments of the invention. The features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:
Healthcare providers that manage multiple patients with a limited number of staff members utilize nurse call systems to facilitate communication between the staff and patients. The nurse call system not only serves to enhance communication between staff and patients, but it also improves communication among staff members. For example, a nurse attending to a patient in a hospital room may register his or her location using a device that interfaces with the nurse call system. In so doing, other staff members of the hospital know the location of the nurse when they view visual indicators on nurse call devices such as corridor lights. Several devices may interface with nurse call systems, for example, a pillow speaker, a pullcord station, corridor lights, staff terminals, etc. The capabilities and functionalities of these devices range from performing complex tasks like making phone calls to simple tasks like turning on an alarm.
Pullcord stations are important to healthcare providers, for example, hospitals, because they can quickly provide a patient an avenue to alert hospital staff or staff members at a healthcare facility when a patient needs help. Embodiments of the disclosure provide pullcord stations that may interface with a networked computing system, for example, a nurse call system, in a healthcare facility. The pullcord stations are further designed to be accessible in wet locations, such as, showers and bathrooms. Since pullcord stations include electronic components for interfacing with, for example, a nurse call system in a healthcare facility, the pullcord stations in the disclosure are waterproof.
Ingress Protection (IP) ratings are used to specify the degree of protection provided by enclosures against intrusion of foreign objects/materials and water. Ingress Protection ratings and requirements are specified in IEC standard 60529. Since pullcord stations mounted in bathrooms or other wet areas are susceptible to damage or malfunction due to water ingress, the waterproofing of the pullcord station is expected to hold up to prevent damage due to water, steam, or liquid ingress. Normal operation of the stations is expected to be maintained when exposed to water or high humidity.
In the environment illustrated in
The pullcord station 104 interfaces with an emergency alert system of a healthcare facility and may be part of a larger group of nurse call devices in a healthcare facility.
The nurse call server 200 includes one or more processors 202, memory 204, network interface 206, storage devices 208, and user interface 210. To simplify the discussion, the singular form will be used for all components identified in the nurse call server 200 when appropriate, but the use of the singular does not limit the discussion to only one of each component. For example, multiple processors may implement functionality attributed to processor 202.
Processor 202 is configured to implement functions and/or process instructions for execution within the nurse call server 200. For example, processor 202 executes instructions stored in memory 204 or instructions stored on the storage device 208. In certain embodiments, instructions stored on storage device 208 are transferred to memory 204 for execution at processor 202. Memory 204, which may be a non-transient, computer-readable storage medium, is configured to store information within the nurse call server 200 during operation. In some embodiments, memory 204 includes a temporary memory that does not retain information stored when power to the nurse call server 200 is lost. Examples of such temporary memory include volatile memories such as random access memories (RAM), dynamic random access memories (DRAM), and static random access memories (SRAM). Memory 204 also maintains program instructions for execution by the processor 202 and serves as a conduit for other storage devices (internal or external) coupled to the nurse call server 200 to gain access to processor 202.
Storage device 208 includes one or more non-transient computer-readable storage media. Storage device 208 is provided to store larger amounts of information than memory 204, and in some instances, configured for long-term storage of information. In some embodiments, the storage device 208 includes non-volatile storage elements. Non-limiting examples of non-volatile storage elements include floppy discs, flash memories, magnetic hard discs, optical discs, solid state drives, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories.
Network interface 206 is used to communicate with external devices and/or servers. The nurse call server 200 may comprise multiple network interfaces 206 to facilitate communication via multiple types of networks. Network interfaces 206 may comprise network interface cards, such as Ethernet cards, optical transceivers, radio frequency transceivers, or any other type of device that can send and receive information. Non-limiting examples of network interfaces 206 include radios compatible with several Wi-Fi standards, 3G, 4G, Long-Term Evolution (LTE), Bluetooth®, etc.
The nurse call server 200 may include one or more user interfaces 210. User interfaces 210 may be separated into input devices and output devices. Output devices are configured to provide output to a user using tactile, audio, and/or video information. Input devices are configured to receive input from a user or an input sensor. Examples of output devices may include a display screen (cathode ray tube (CRT) display, liquid crystal display (LCD) display, LCD/light emitting diode (LED) display, organic LED display, etc.), a sound card, a video graphics adapter card, speakers, magnetics, or any other type of device that may generate an output intelligible to user. Examples of input devices may include a presence-sensitive screen or a touch-sensitive screen, a mouse, a keyboard, a video camera, microphone, a voice responsive system, or any other type of input device.
A host of nurse call devices 212 may be connected to the nurse call server 200. Nurse call devices 212 include corridor lights, bedside stations, bath stations, emergency call stations, SIP interface, PC consoles, TAP interface, patient station, and staff terminal. The architecture in
The cord 302 may be pulled by a patient or an enduser for signaling to a nurse for help. The cord 302 may be extruded, for example, a polyvinyl chloride (PVC) exterior with interior reinforcing strands, with smooth, slippery bacterial-resisting exteriors. The cord 302 may also be made from woven strands of material, for example, nylon, cotton, etc. The cord retainer 304 retains the cord 302 and attaches to the actuator post 308. The face plate 306 provides an opening for the actuator post 308 to pass through to interface with the cord retainer 304. The cord retainer 304 includes an opening that interfaces with one extreme of the actuator post 308, allowing the cord retainer 304 to pivot so that a call can be actuated when the cord is pulled perpendicular to the wall plane in any direction, parallel to the wall plane in any direction, or in an intermediate direction between the perpendicular and parallel directions. The rounded bottom (half-toroid) of the cord retainer 304 provides a smooth action of the actuator to place a call when the cord is pulled from any direction. The cord retainer 304 acts like a lever that operates in 360° to move or pry the actuator post 308 when there is a side-force applied to the actuator post 308 by the cord retainer 304 in response to the cord being pulled in some direction. The actuator post 308 includes a metalized, flat surface that is inductively coupled to a sensor on the circuit board 312 and used for activating the call signal to the nurse.
The wall plate 310 provides holes for mounting the waterproof pullcord station 300 to a wall. The wall plate 310 has an opening on its backside for accepting and mounting the circuit board 312. Also on the backside, the wall plate 310 has a round channel for sealing to an O-ring 314. The wall plate 310 also includes one or more debossed pins for locking to the back cap 316. The backside of the wall plate 310 faces the wall that the waterproof pullcord station 300 is mounted, and in some instances, the back cap 316 protrudes into the wall.
The circuit board 312 includes an inductive sensing switch for sensing the inductive target on the flat surface of the actuator post 308. The inductive target may be realized by making the flat surface of the actuator post 308 a conductive or a metalized surface. The inductive sensing switch may be a Texas Instrument® inductive sensing switch. The circuit board 312 further provides an electrical connection point to a central computer system, for example, the nurse call server 200. The circuit board 312 may include in addition to the wired interface with the electric cable 320 a wireless communication interface.
The O-ring 314 provides a sealing function when compressed between the wall plate 310 and the back cap 316 at the time of installation. The O-ring 314 may be manufactured with different materials that may be compressed while providing a sealing function, for example, silicone, nitrile rubber (buna-N), and ethylene propylene diene monomer (EPDM) rubber. The back cap 316 includes a round channel for sealing to the O-ring 314. The sealing function provided by the O-ring 314 prevents water and other fluids from entering the pullcord station 300 through the interface between the wall plate 310 and the back cap 316. The back cap 316 may also include a number of embossed channels for locking to the wall plate 310, for example, four embossed channels. The back cap 316 may be made from plastic. The back cap 316 may further include an opening for receiving the cable grommet 318, for example, an IP-67 cable grommet.
The cable grommet 318 has a pass through opening for sealing to a category type electrical cable. The cable grommet 318 fits snugly to an opening in the back cap 316 and provides a sealing function for the electric cable 320. The sealing function provided by the cable grommet 318 prevents water or other fluids from entering the pullcord station 300 through the opening on the back cap 316 that receives the cable grommet 318.
The cord retainer 402 serves to retain or hold the cord in place. When installing the cord to the cord retainer 402, tool termination, tying a knot, and fasteners are not required. The ‘V’ shape in the middle allows for the cord to sit in place without sliding back and forth. As the cord is used over time and due to cord stretching and/or wear and tear, it's diameter changes, and the ‘V’ shape allows the cord to slip further down into the ‘V’ formed by the ‘V’ shape.
The ‘V’ shape cavity of the cord retainer 402 allows for a progressive lock of a cord which might be of varying diameter and might also be constructed of material which, when under loads applied by pull forces, deforms and varies its diameter. By allowing for a progressive locking function, the V-shape cavity ensures that a smaller diameter cord will simply be pulled deeper in to the ‘V’ rather than pulling though openings 406 and 408 and becoming unlocked.
In some embodiments, the cord retainer 402 is provisioned with more than two openings 406 and 408. The more than two openings allows for providing additional friction when an installed cord is pulled. The plurality of openings on the cord retainer 402 will allow the cord to be woven through from one opening to another.
In some embodiments, the cord retainer 402 is not provisioned with a high friction area but other means of attaching the cord to the cord retainer 402 are used. For example, the cord may be guided through opening 406 and out opening 408, and a knot may be tied to prevent the cord from slipping out of the cord retainer through opening 408 and then through opening 406. In another embodiment, the cord may be guided through opening 406 and a knot is tied so as to prevent the cord from slipping out of the cord retainer through the opening 406. In another embodiment, a washer is provided such that the cord is affixed to the washer and the washer has an outer diameter that prevents the washer from passing through the opening 406. In another embodiment, a zip tie may be used to attach the cord to the cord retainer.
The cord retainer 402 is able to lock (and unlock) with an actuator post without requiring an installer to use a tool or disassemble the pullcord station of the cord retainer 402. In one embodiment, the cord retainer 402 and the actuator post have a compression fit where the head of the actuator post compresses to pass into the opening 406 from the bottom of the cord retainer 402. Then once inside the inner cavity of the cord retainer 402, the head of the actuator post expands to provide a locking mechanism, preventing the two pieces (the actuator post and the cord retainer 402) from being separated. The two pieces remain unseparated until enough force is applied to once more sufficiently compress the head of the actuator post to allow it to pass though the opening 406 from the bottom of the cord retainer 402. When the head of the actuator post expands inside the inner cavity of the cord retainer 402, the radial surface portions 410 prevent the expanded head of the actuator post to separate from the cord retainer 402. When compressed, the head of the actuator post can pass through the opening 406 from the bottom of the cord retainer 402, but when expanded, the head of the actuator post cannot pass through the opening 406 from the bottom of the cord retainer 402 because of the radial surface portions 410.
The cord retainer 602 is able to lock (and unlock) with an actuator post without requiring an installer to use a tool or disassemble the pullcord station of the cord retainer 602. The cord retainer 602 has the opening 608 on the bottom of the cord retainer 602 which allows the actuator post to first enter the inner cavity of the cord retainer 602 from the bottom into an unlocked outside position. The actuator post then slides past a region of high friction, which the shaft of the actuator post must pass though, before reaching the center of the inner cavity of the cord retainer 602. This center region includes the radial surface portions 610 designed to allow the actuator post to snap into and out of the inner cavity of the cord retainer 602. Once seated in the center region in the inner cavity of the cord retainer 602, the actuator post is locked into place with the cord retainer 602.
The cord retainer 702 is able to lock (and unlock) with an actuator post without requiring an installer to use a tool or disassemble the pullcord station of the cord retainer 702. The cord retainer 702 includes an opening (the port 704) on the side of the cord retainer 702 which allows the actuator post to pass laterally into the inner cavity of the cord retainer 702 without compressing the head of the actuator post. In some embodiments, an element of the inner cavity of the cord retainer 702 which prevents the actuator post from sliding out of the port 704 is a region of high friction which the shaft of the actuator post must pass though before reaching the center of the inner cavity of the cord retainer 702. This region is designed to allow the actuator post to snap into and out of the center of the inner cavity of the cord retainer 702. Once seated in the center of the cavity of the cord retainer 702, the actuator post is locked into place with the cord retainer 702. This design allows the cord retainer 702 to transmit pull forces without unlocking or disconnecting from the attached actuator post.
The actuator post 1000, when included in the pullcord station 300, may have a spring installed on the stem 1004. The spring is added to ensure that the actuator post 1000 returns to an original position. Since the actuator post 1000 includes metallic material in at least its bottom 1006 section, when actuated, the conductive material moves towards and away from an inductive sensor at the electronic circuit 312. One advantage to this design is that by removing mechanical pulling engaging a mechanical switch, longterm lifetime is increased. Over time, there is no wear and no bridinging due to mechanical flexing. The inductive sensing can thus have billions of operations compared to the thousands of operations of mechanical sensing. The bottom 1006 may include the flat metallized surface through a metal plating process, by adhering a metal foil to the bottom 1006 section, or having the entire actuator post 1000 constructed out of metal.
To facilitate compression, the head section may include more than two subsections as shown in
Sensors 1702 include, for example, inductive sensors. The analog receivers 1706 include amplifiers and analog to digital converters (ADCs) that receive analog electrical signals from the sensors 1702, amplify the analog electrical signals, and convert the analog electrical signals to digital signals in order to interface with processor 1708. The digital signals are amplified and provided to processor 1708.
Buttons 1704 include, for example, cancel button. Buttons 1704 include buttons and other switch mechanisms on the pullcord station that provide signals to the processor 1708 through the I/O interface 1710. Network interface 1712 includes hardware for transmitting and receiving information using one or more wireless or wired networks. The wired networks may include life-safety networks, for example, nurse call bus specific networks that transmit information below 38 kilobits per second (kbs). The wired networks may also include standard healthcare facility Ethernet. Wireless networks include Wi-Fi, ZigBee, 3G, 4G, Long-Term Evolution (LTE), Bluetooth®, etc.
Central computer 1714 encompasses a central system in a healthcare facility. An example of a central computer 1714 includes the nurse call server 200. Once an appropriate call level is determined, central computer 1714 coordinates with other nurse call devices 212 to alert staff in the healthcare facility of the call.
Some embodiments of the disclosure may include an additional inductive sensing call actuation mechanism to that of the actuator post in the form of a button. The button may be assembled into a retaining cavity of a faceplate of a waterproof pullcord station. The button may be realized using multiple design methodologies, but despite the methodologies, the button may include the following properties: (1) The ability to be assembled into the faceplate of the waterproof pullcord station, such that the button is able to travel towards and away from an electronic circuit with an inductive sensor, housed in the waterproof pullcord station, when pressed and released respectively; and (2) The ability to cause the inductive sensor in the electronic circuit to detect its presence and absence when moved closer and then farther away from the inductive sensor.
A button can be constructed with a single body or multiple pieces in an assembly in order to realize the aforementioned properties. In one embodiment, a bottom section of the button can be plated with a conductive material to act as an inductive sensor target, and in another embodiment, the bottom section of the button can be constructed to accept the mating and assembly of a separate inductive sensor target sub-part. This separate inductive sensor target sub-part can be a standalone plated plastic part or a solid body metallic part which is captured by a button cap section of the button. The button cap section of the button may include a surface upon which a user may press in order to create a button actuation (call or cancel) on the station.
In some embodiments, the button cap section of the button may also include mechanical elements, for example, spring mounting posts, which provide for the capture of springs. These springs provide a return force tension which causes the button to move away from the electronic circuit inductive sensor when the button is released. These springs may be located outside the range of the electronic circuit inductive sensor and are not wirelessly coupled to it.
The button cap section of the button may also include mechanical elements, for example, button alignment guides, which prevent the button from tilting more than a predetermined angle, for example, 18 degrees, out of planarity with the faceplate when being pressed and while moving towards the inductive sensor of the electronic circuit. The button cap section of the button may further include more mechanical elements, for example, button retaining snaps, which couple to the face plate button retaining cavity of the faceplate. These button retaining snaps flex and allow for assembly of the button into the faceplate. The button retaining snaps my then return to their original orientation and prevent the button from traveling beyond a designed distance away from the electronic circuit inductive sensor when the button is not being pressed. The button may be under the spring tension force pushing away from the electronic circuit inductive sensor so the button retaining snaps prevent the button from traveling beyond the distance even under this spring tension force. The button retaining snaps further prevent the button from being un-coupled from the faceplate unintentionally.
Embodiments of the disclosure provide pullcord stations meeting a waterproof standard, for example, an IP-67 rated nursecall pullcord station. The pullcord station provides water tight call placement, that is, water tight call placement throughout actuation of the cord of the pullcord station. The cord of the pullcord station can be actuatored in any direction. In some embodiments, the entire pullcord station can be submerged while retaining IP-67 level of protection.
Embodiments of the disclosure further provide a waterproof pullcord station with no flexible membranes used for cord entry. In addition, the waterproof pullcord station also has a water tight cancel button and a water tight cable connection. The pullcord station is amenable to using inexpensive components to achieve water tight cable connection. For example, off the shelf IP-67 grommet may be used for cable entry; in-line, general use, male headers pins and female connectors may be used; and cable used for the pullcord station may be field terminated, plugged and unplugged and replaced. In some embodiments, a single twist lock cap is used for inserting the circuit board during manufacturing and servicing in the field without the use of caulk or other liquid gel sealant. Standard O-rings may be used for cable seal, and adhesives or liquid sealants are not necessary to achieve the waterproof function. In some embodiments, the provision of a twist lock cap also provides assurance of a water-tight seal to ensure an installer that the back cap is secured to the wall plate. Embodiments of the disclosure further provide a waterproof pullcord station where a place of water entry is provisioned as far away from a water source as possible.
Embodiments of the disclosure further provide a water tight assurance indicator. Light transmission from inside the sealed housing may pass through the cosmetic face of the pullcord station. The circuit board disposed within the sealed housing of the pullcord station may include one or more light emitting diodes (LEDs) that emit light that travels through a light pipe provisioned in the wall plate of the pullcord station. An opening may be provided through the cosmetic face of the pullcord station to allow the emitted light to be visible to the user. The emitted light serving as the water tight assurance indicator signifying that the electronic components of the pullcord station are working properly and are not exposed to water, steam, or other liquids and/or condensation.
Embodiments of the disclosure provide a waterproof pullcord station where magnets are not used in the design. Additionally, steam will not impede call placement in the waterproof pullcord station design since inductive sensing is used rather than optical sensing. Electrical current carrying components are not exposed or accessible on the installed or sealed station. Sensing of call placement is unaffected by direct current (DC) magnetic fields.
Embodiments of the disclosure provide a waterproof pullcord station where the sealed housing opening is located on the backside of the device facing the wall on which the device is mounted. The frontside of the device on which the face plate is exposed is meant to be exposed to water and steam and is thus completely sealed with no breaks or openings. The face plate of the device is able to be removed for service and cleaning without opening the sealed housing of the waterproof pullcord station. In some cases, portions of the waterproof pullcord station which are to be exposed to water or other liquids allow for drainage and prevent retention of the water or liquid.
Embodiments of the disclosure further provide a waterproof pullcord station with a cord retainer designed to be serviceable in field without the use of specialized tools for cord replacement or station cleaning. In some cases, the cord retainer has cord locking mechanisms without the use of knots or fasteners. Thus, while in field, the cord retainer is designed to be able to lock and free the cord of the pullcord station by hand, without tools.
Embodiments of the disclosure provide a waterproof pullcord station with a cord retainer that interfaces with an actuator post, where the cord retainer and the actuator post are snapped together. A cord is attached to the cord retainer, so the cord retainer acts as an intermediary between the cord and the actuator post. Several embodiments may be constructed or envisioned for attaching the cord to the cord retainer. For example, the cord may pass through a hole in the cord retainer and then knotted to prevent the cord from slipping through the hole. In another example, a washer may be provisioned so that the cord is knotted to the washer and the washer prevents the cord from slipping through the hole. Other examples for attaching the cord to the cord retainer include using a zip tie or providing a series of holes on the cord retainer such that the cord may be woven through the holes to gain additional friction.
Embodiments of the disclosure provide a waterproof pullcord station with a cord retainer that interfaces with an actuator, with the ability for the cord retainer to lock (and unlock) with the actuator post without requiring an installer to use a tool or disassemble the pullcord station. While in use the cord retainer is pulled in various directions under various amounts of force. The cord retainer performs its intended function of transmitting those pull forces from the attached cord to the attached actuator post. The cord retainer transmits those pull forces without unlocking or disconnecting from either the attached cord or the attached actuator post. These two features, the ability to be locked and unlocked quickly and without a tool, and the ability to reliably transmit pull forces without becoming unlocked are both delivered by the design of the cord retainer.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
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