Abstract: There is provided a hair cutting device for cutting hair on a body of a subject, the hair cutting device comprising a light source for generating light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in or on hair; a cutting element that comprises an optical waveguide that is coupled at a first end to the light source to receive light, wherein a portion of a sidewall of the optical waveguide forms a cutting face for contacting hair; a light sensor that is coupled to the optical waveguide away from the first end, wherein the light sensor is for measuring the light level in the optical waveguide and for providing an output signal representing the measured light level; and a control unit that is coupled to the light source, and coupled to the light sensor to receive the output signal, wherein the control unit is configured to determine a measure of the amount of input light transmitted across the optical waveguide from the measured light level and an input li

Abstract: Microwave catheter apparatuses, systems, and methods for achieving renal neuromodulation by intravascular access are disclosed herein. One aspect of the present application, for example, is directed to apparatuses, systems, and methods that incorporate a catheter treatment device comprising an elongated shaft. The elongated shaft is sized and configured to deliver a microwave transmission element to a renal artery via an intravascular path. Renal neuromodulation may be achieved via dielectric heating in the presence of microwave irradiation that modulates neural fibers that contribute to renal function or alters vascular structures that feed or perfuse the neural fibers.

Abstract: A variable-frequency stimulator for electrosurgery includes an impedance analyzer to identify the electrical impedance of biological tissue being treated by an electrosurgical instrument, such as a laparoscope. Based on the identified tissue impedance, a controller adjusts the frequency of electrical current delivered to the electrosurgical instrument to reduce, minimize or normalize the impedance of the tissue, thereby preventing collateral damage to the tissue in and about the surgical site. Additionally, the laparoscope may be configured with multiple electrically conductive grasping arms that are used to deliver the electrical current to the surgical site. The conductive grasping arms provide multiple current paths for the electrical current to flow, thus concentrating the electrical current at the surgical site during an electrosurgical procedure.

Abstract: An improved endoprosthesis with an embodiment that includes a generally cylindrical graft portion that extends along a longitudinal axis to define a flow passage and a plurality of stent hoops. The plurality of stent hoops are connected to the graft portion and disposed in a spaced apart relationship along the longitudinal axis. There is at least a first suture disposed along on the outer surface of the main body. The first suture connects at least two of the spaced apart stent hoops together. The first suture also includes unidirectional barbs (or multidirectional barbs) configured to reduce movement of the main body with respect to a direction of blood flow in an artery.

Abstract: A method for removing hair by thermolysis is provided. The method steps include oscillating a direct current to create an alternating current (“AC”) micro-pulse, pulsing the AC micro-pulse on and off continuously, delivering the AC micro-pulse to a probe, applying the probe to a hair follicle, and inverting the direction of the AC micro-pulse on the hair follicle. When the probe is applied to the hair follicle, the AC micro-pulse travels from the top of the dermis of the hair follicle to a dermal papilla of the hair follicle. The AC micro-pulse reverses direction at the dermal papilla and travels to the top of the dermis of the hair follicle. The AC micro-pulse produces heat that destroys the tissues controlling the growth of the hair follicle.

Abstract: Methods are disclosed for treating cell components, cells, organelles, organs, and/or tissues with acoustic energy, electromagnetic energy, static or alternating electric fields, and/or static or alternating magnetic fields in the presence or absence of exogenous particulate agents for therapeutic applications.

Abstract: A dielectric spacer for use during microwave ablation of tissue is disclosed. The dielectric spacer includes a housing having a predetermined thickness and a skin-contacting bottom surface. The housing is configured to be filled with a dielectric material having a predetermined dielectric permittivity. The housing is further configured to be placed on the tissue in proximity with at least one microwave antenna assembly, wherein the thickness and the dielectric permittivity are configured to shift a maximum voltage standing wave ratio of the at least one microwave antenna assembly.

Abstract: A surgical cautery device, system, and method of use may apply bipolar and/or sesquipolar electrocautery to target tissue via a pair of instruments with other primary surgical functions. The surgical cautery device and system may include first and second elements capable of forming an electrical circuit. The second element may be independently positionable with respect to the first element. The first and second elements may also include a surgical component with an independent surgical function. Exemplary surgical components include a rotary blade, a cutting tool, a grasper tool, a micro-scissors tool, a micro-grasping forceps tool, a dissector, a micro-dissector, curette, and a suction cannula. On some occasions, one of the surgical components may be interchangeable with another surgical component.

Abstract: A device configured to cut hair using laser light includes a handle portion and a shaving portion. The handle portion includes a battery and a laser light source. The laser light source is coupled to and configured to receive power from the battery. The laser light source is also configured to generate laser light having a wavelength selected to target a predetermined chromophore to effectively cut a hair shaft. The shaving portion includes a support and a single fiber optic supported by the support. The fiber optic has a proximal end, a distal end, an outer wall, and a cutting region positioned towards the distal end and extending along a portion of the side wall. The fiber optic is positioned to receive the laser light from the laser light source at the proximal end, conduct the laser light from the proximal end toward the distal end, and emit the light out of the cutting region and toward hair when the cutting region is brought in contact with the hair.

Abstract: A surgical introducer including a body portion, a shaft and a sensor is disclosed. The body portion includes a reference indicator. The shaft defines a longitudinal axis and is positionable adjacent the body portion. The shaft is rotatable with respect to the body portion and includes a longitudinal indicator and a circumferential indicator. The sensor is disposed in mechanical cooperation with a distal portion of the shaft and is adapted to provide physiological data pertaining to a surgical worksite. At least a portion of the sensor is substantially aligned with the circumferential indicator. Rotation of the shaft with respect to the body portion causes displacement between the circumferential indicator and the reference indicator. Longitudinal movement of the shaft with respect to the body portion causes displacement between the longitudinal indicator and the reference indicator.

Abstract: A device and system for applying a directed electrical current to heated hair, for at least damaging if not destroying the hair follicle with the electrical current. The current may optionally be AC or DC current. The device for hair treatment, may include a heat source; and a source of electricity for delivering a charge upon contact of the hair with the heat source. The heat source may include a filament. Further, the filament can be a wire of about 0.03 mm to about 0.2 mm in diameter and/or constructed from a nickel chrome alloy.

Abstract: Methods, apparatus and systems for modifying hair follicles are disclosed herein. A method for modifying hair follicles may comprise inserting a tissue dissecting and modifying wand (TDM) into an incision in a patient's skin. The TDM may comprise a tip having a plurality of protrusions with lysing segments positioned between the protrusions. The TDM may also comprise an energy window positioned on top of the TDM that is configured to deliver energy to incapacitate hair follicles. After separating tissue using the lysing segment(s) to define a target region, the energy window may be activated and moved around within the target region to incapacitate hair follicles. In some implementations, the energy window may be activated prior to separating the tissue such that the tissue is separated while hair follicles are incapacitated within the target region.

Abstract: A device and method to cause hair loss or prevent or inhibit hair growth. The invention uses plasma (ionized gas) that is generated by flowing gas in close proximity to an electrode that has a high potential applied to it. The result is a stream of charged gas particles that are directed to the skin that contains hair. The flowing stream of gas is held above the surface of the skin. Additionally, a grounded conductive material is affixed to the skin to dissipate any charge buildup on the skin and focus the plasma.

Abstract: An endoscopic bipolar forceps includes a housing having a shaft affixed thereto, the shaft including jaw members at a distal end thereof. The forceps also includes a drive assembly which moves the jaw member relative to one another for manipulating tissue and a knife assembly for cutting tissue disposed between jaw members. The forceps also includes a knife lockout mechanism operatively connected to the drive assembly. Movement of the drive assembly moves the knife lockout mechanism from a first orientation in obstructive relationship with the knife bar to prevent movement thereof to a second position which allows selective, unencumbered movement of the knife assembly to cut tissue disposed between the jaw members.

Abstract: A manual shaving device that includes a support having at least one razor blade designed to cut a hair as it passes over it mounted thereon and at least one conducting member designed to transmit an electric current to a root of the hair as it passes over it, the electric current being designed to damage a follicle of the hair by electrolysis.

Abstract: This invention relates to a method of straddling an intraosseous nerve with an energy transmitting device to improve the therapeutic treatment of the nerve.

Abstract: The present invention discloses a pivotal disc is pivotally coupled to a first brace and a second brace. The pivotal disc has a motion-limit member and a positioning member limiting the angle by which the second brace rotates with respect to the first brace with the pivotal disc being the axis and fixing the angle between the first and second braces. The present invention is characterized in that the motion-limit member uses a range-adjust member to push a slide block and determine the range that a block portion of the second brace is blocked by the slide block, and that the positioning member uses a switch knob actuates on end of a positioning rod to engage with or depart from a positioning notch on the pivotal disc, and that the pivotal disc has two limit elements to define the maximum movement range of the first brace and the second brace.

Abstract: A device and system for applying a directed electrical current to heated hair, for at least damaging if not destroying the hair follicle with the electrical current. The current may optionally be AC or DC current. The device for hair treatment, may include a heat source; and a source of electricity for delivering a charge upon contact of the hair with the heat source. The heat source may include a filament. Further, the filament can be a wire of about 0.03 mm to about 0.2 mm in diameter and/or constructed from a nickel chrome alloy.

Abstract: Disclosed are a method and a device useful for performing cosmetic or medical procedures of an in vivo portion of tissue. The method includes contacting an in vivo portion of tissue with a portion of a pad, substantially saturating the pad with a reactant, contacting the pad with a first electrode so that the first electrode is proximate to the portion of the pad proximate to the in vivo portion of tissue. The method further includes contacting the pad with a second electrode so as to provide an electrical path between the first electrode and the second electrode through the reactant, passing a DC voltage through a circuit including the first electrode, the reactant and the second electrode, thereby forming at least one of: an electrolytic effect, and an electrolytic product of the reactant, proximate to the first electrode.

Abstract: The invention relates to an electrolysis hair-removal device comprising: a central control unit (4) which is equipped with a microprocessor; and hair-removal patches (8) of variable size, which are adapted to the different parts of the body to be treated, as well as contact patches (10) which can be used to create the electrolysis current on the skin. The invention is characterised in that the device comprises a hair-removal patch identification system which enables the above-mentioned microprocessor to identify said patches and automatically to adapt the duration for which the current is applied in accordance with the intensity selected by the user in order to deliver a constant dose of energy that is specifically associated with the size of the selected hair-removal patch.

Abstract: An orthopedic device in the form of an unloading osteoarthritic knee brace has proximal and distal frame members with a flexion-extension hinge positioned between the proximal and distal frame members. At least one articulating free hinge is positioned in an upright between the flexion-extension hinge and one of the proximal and distal frame members. The free hinge provides free rotation of the proximal or distal frame member about the anteroposterior axis with respect to the flexion-extension hinge.

Abstract: An orthotic device includes a frame having a first shell defining front and rear surfaces, and extending longitudinally into the anterior and posterior sides of the brace. The first shell defining an opening located on the posterior side of the brace. A tightening mechanism is mounted onto the first shell, and has a ratchet strap located along the rear surface of the first shell and a ratchet device mounted on the front surface of the first shell so as to extend partially into the opening and engage the ratchet strap. An elongate tensioning device having a first end portion is connected to the ratchet strap, and the first end portion of the tensioning device extends along the rear surface of the first shell. The tensioning device has a second end portion anchored to a portion of the frame. A channel is mounted to the rear surface of the first shell and entirely encloses at least a portion of the ratchet strap. The tensioning device is a textile-based and substantially inelastic strap.

Abstract: There is described a method of epilation using an insulated probe connected to an epilator apparatus supplying multiple pulses of energy that created concentrated heat at the probe tip. The steps of the method comprise inserting the probe tip into the hair follicle; positioning the probe tip at a position corresponding to either the bulb or the bulge; activating the apparatus to generate heat at the probe tip using predefined settings; and displacing the probe tip from the position to the other of the bulb and the bulge with continuous generation of heat using the multiple pulses of energy at the probe tip.

Abstract: A manual shaving device that includes a support having at least one razor blade designed to cut a hair as it passes over it mounted thereon and at least one conducting member designed to transmit an electric current to a root of the hair as it passes over it, the electric current being designed to damage a follicle of the hair by electrolysis.

Abstract: Apparatus and methods for removing hair and/or devitalizing follicles using electromagnetic energy to actively target and treat a hair and/or a follicle are disclosed. The electromagnetic energy can be of a selective or non-selective wavelength.

Abstract: The electrolytic depilation device works by electrical contact with the skin of an individual whose hair is to be treated by electrolysis. It comprises a case containing an electrical power supply source, an electronic control circuit connected to the electrical power supply source for supplying a first electrode and a second electrode of different polarity. The electrodes are located at a distance from one another to apply a current that initiates electrolysis at the level of the hairs to be treated. At least the first electrode is elongated and located on one of the ends of the case so as to be applied against the skin over its entire length. The electrode has a shape that is convex in cross section.

Abstract: The present invention provides method for removal of body hair using electroporation using an apparatus having a pulse generator capable of generating electrical pulses of the desired amplitude and duration to kill hair follicles and an applicator having a first electrode placed in contact with a hair follicle and a second electrode interacting with the first electrode to provide an electroporating field in the tissue volume surrounding a hair to be removed. The method utilize a TENS system to provide patient relief from discomfort experienced by application of the electroporation pulses.

Abstract: Methods, Devices and systems for hair removal combine the application of RF electromagnetic energy to the skin with application of heat from heating element(s) to hair(s) of the skin. The devices or systems may include RF electrodes and one or more heating elements. RF energy from an RF generating unit is applied to the RF electrodes. Heat is applied to hair shafts by the heating element(s). The devices and systems may be hand held or may include a hand held part connected to a base unit. In operation, the hand held device or part is moved along the treated skin region. The combined effect of RF energy application to the skin and heating of the hair shaft results in improved hair removal and may reduce hair re-growth. The devices and systems may also include safety improving features preventing skin damage by reducing sparking or excessive skin heating by the heating element(s).

Abstract: The present invention provides apparatus and method for removal of body hair using electroporation. The apparatus has a pulse generator capable of generator electrical pulses of the desired amplitude and duration to kill hair follicles and an applicator having a first electrode placed in contact with a hair follicle and a second electrode interacting with the first electrode to provide an electroporating field in the tissue volume surrounding a hair to be removed. The apparatus may include a TENS system to provide patient relief from discomfort experienced by application of the electroporation pulses.

Abstract: A joint and method for producing a joint in an endovascular graft. In one embodiment, a flap of a flexible material portion of an endovascular graft is folded about a portion of an expandable member to form a loop portion. The flap is secured in the loop configuration so that tensile force on the expandable member is transferred into a shear force on the fixed portion of the flap.

Abstract: The present invention provides apparatus and method for removal of body hair using electroporation. The apparatus has a pulse generator capable of generator electrical pulses of the desired amplitude and duration to kill hair follicles and an applicator having a first electrode placed in contact with a hair follicle and a second electrode interacting with the first electrode to provide an electroporating field in the tissue volume surrounding a hair to be removed. The apparatus may include a TENS system to provide patient relief from discomfort experienced by application of the electroporation pulses.

Abstract: A method and apparatus of making repairs with graft ligaments. In one form, the method for graft ligament reconstruction comprises (i) harvesting a graft ligament consisting entirely of soft tissue; (ii) compacting the graft ligament through compression so as to significantly reduce the cross-sectional area and increase the density of the collagen material of the graft ligament; and (iii) deploying the compressed graft ligament in the human body. In another form, the apparatus for graft ligament reconstruction comprises a graft ligament having a given diameter and a given cross-sectional area; and a compacting instrument having at least one surface to contact the graft ligament and to decrease the given cross-sectional area of the graft ligament to a reduced cross-sectional area, whereby the graft ligament with the decreased cross-sectional area may be positioned within a bone tunnel having a cross-sectional area smaller than the given cross-sectional area of the graft ligament in its original state.

Abstract: Decellularized vascular prostheses that are resistant to thrombus occlusion and have a low level of immunogenicity and methods of making same are disclosed. The prostheses have high mechanical strength, resist aneurysm, rupture, and allow for secure surgical sutures while maintaining structural integrity. The vascular prostheses provided are blood vessels, valves or portions of vessels containing valves. There is also a method useful for coating synthetic vascular stents.

Abstract: The method for hair removal applies an electrolytic procedure, followed sequentially by a thermolytic procedure. The electrolytic method involves preparing the area to be treated by allowing silver/silver chloride gel to remain on the area for a period long enough to allow the electrolyte gel to diffuse through the skin, then applying a cotton swab to a galvanic probe and swabbing circles of the electrolyte gel about the treatment area while applying galvanic current for two passes about the area. Then the hair is grasped by tweezers before removing the electrolyte gel from the area, and an RF current is applied through the tweezers for twenty to twenty-five seconds while gently pulling the hair.

Abstract: The method for hair removal applies an electrolytic procedure, followed sequentially by a thermolytic procedure. The electrolytic method involves preparing the area to be treated by allowing silver/silver chloride gel to remain on the area for a period long enough to allow the electrolyte gel to diffuse through the skin, then applying a cotton swab to a galvanic probe and swabbing circles of the electrolyte gel about the treatment area while applying galvanic current for two passes about the area. Then the hair is grasped by tweezers before removing the electrolyte gel from the area, and an RF current is applied through the tweezers for twenty to twenty-five seconds while gently pulling the hair.

Abstract: Method of removing hair provides for applying radio frequency radiation to a selected skin zone in conjunction with applying ultrasound waves to the skin zone, with pulling the slackened hair out. A combination of a radio frequency generator, and an oscillator that are connected to tweezers constitute a hair removal device implementing the method. A radio frequency power selector enables selecting a suitable mode of operation depending on the texture of skin and its sensitivity.

Abstract: An apparatus and method for treating an undesired presence on an individual includes a CPU coupled to a laser control unit and a robotic arm control unit. A scanning area or volume is defined on the individual that includes the undesired presence. The CPU controls the robotic arm to move the laser and camera about the scanning area or volume while the camera scans individual portions of the scanning area or volume. The CPU receives this information from the camera and determines, based on the scanning, whether a particular portion includes part of the undesired presence. When the particular portion includes part of the undesired presence, the CPU actuates the laser. This process continues for all portions of the scanning area or volume. In an alternative embodiment, the CPU controls the robotic arm control unit to scan the entire area or volume and determines locations where there is an undesired presence.

Abstract: The invention concerns a probe for applying a high frequency electromagnetic energy flux on the skin through a mixture of conductive gel and a treatment product, designed to cause the treatment product to penetrate into the skin. The probe is provided with a non-conductive bearing surface (14), having a plurality of openings (6) around or in the proximity of which inductor elements (5) arranged in successive layers emit an electromagnetic field. The openings (6) emerge through an orifice (3) and contain the gel/treatment product mixture whereof the penetration into the skin is activated by the electromagnetic field. Advantageously, the probe further comprises at least one source of laser electromagnetic radiation (8) arranged inside or aligned with at least one opening (4) emerging in the bearing surface (14), so as to act jointly with the electromagnetic radiation emitted by the inductor element (5).

Abstract: Multiple hair removal system includes a conductive layer including a conductive material. The conductive material functions to provide electromagnetic energy from a source to hairs to be treated that extend up into and/or through the conductive layer and contact the conductive material. A method of removing multiple hairs and inhibiting future hair growth includes applying a conductive layer, applying electromagnetic energy for a period of time sufficient to destroy the matrix area of the hair, and allowing the treated hair to either be removed immediately or to stay in the skin for a period of time sufficient for the chemical reaction induced at the matrix area to continue long enough to destroy the matrix area and prevent regrowth of the hair.

Abstract: A control system to establish consistency in carrying out an epilation procedure, in which a main microcomputer is associated with an RF amplifier chain for producing RF energy to be transmitted to a hair follicle of a patient by means of an epilator probe, and a slave microcomputer is associated with the main microcomputer and the RF amplifier chain to protect the patient from a misapplication of RF power, the slave microcomputer independently monitors pulse timing and cooperates with the main microcomputer to enable the RF amplifier chain.

Abstract: Method and apparatus for controlling an epilation procedure in which a removal process is adaptively controlled for optimum removal prevention of scarring and minimizing sensation, and profiling RF power supplied as an inverse square of measured impedance based on a normalizing impedance.

Abstract: An epilator includes a pair of tweezers mounted at the leading end of a hollow wand body. An electrical circuit board for generating a radio frequency current is mounted in the trailing end of the wand body. The trailing end of the wand body is coated with a metabolized conductive coating to shield against electromagnetic interference. The tweezers are maintained in normally spaced apart relation to one another by a bias member that is compressed by a manually-operated actuator. The bias member includes an extension member that is in continuous contact with a first tweezer member and which makes contact with an electrical contact member mounted in the second tweezer member when the tweezer members are brought into hair-gripping relation to one another by actuator-driven compression of the bias member.

Abstract: An electrolysis needle assembly having a shank for attachment to an electrolysis handle which includes an air flow source and a forward portion from which the needle extends. Each is provided with an air flow slot so as to enable air to be directed from the handle along the needle assembly to the skin of the patient and in which a needle protective cap is provided for such forward end. The cap is used to manipulate the assembly as in attaching and removing the needle from the electrolysis handle.

Abstract: A method of removing multiple hairs and inhibiting future hair growth includes the steps of applying a conductive solution to the hair, applying power for a period of time sufficient to destroy the matrix area of the hair, and allowing the treated hair to either be removed immediately or to stay in the skin for a period of time sufficient for the chemical reaction induced at the matrix area to continue long enough to destroy the matrix area and prevent regrowth of the hair. The power may be applied through a conductive element of a comb. The comb is configured for carrying out the method. The comb may be provided with a moveable clamp for treating hair. The movable clamp may likewise be used to grasp and to remove treated hair when the grasped/clamped treated hair is moved relative to the skin by movement of the comb.

Abstract: An applicator probe (10) for applying a high-frequency electromagnetic energy flux to the skin through a conducting gel, the applicator probe having a non-conducting contact surface (14) which is applied to the skin. This surface includes a plurality of discrete electromagnetic emission points or areas (16) defined by parts of the turns of a coil (12) which is set back from the surface when the applicator probe is in use. The applicator probe according to the invention consists of a flexible sheet which is able to conform to the part of the body onto which it is applied. The flexible sheet includes a non-conductive lower internal portion (or "sole") and a non-conductive upper/external portion (or "back"). At least the lower portion is a sole (14) provided with a row of cavities and which forms the contact surface. The cavities contain the conducting gel which is applied to the skin. The generally flat turns of the coil are arranged in a sandwich configuration between the openwork sole (14) and the back.

Abstract: Method for the very rapid removal of hair through the use of electromagnetic (e.g., AC, DC, blend, and laser) energy by treatment of the hair prior to the application of such electromagnetic energy to reduce the electromagnetic energy resistance of the hair. Such hair treatment may include applying conductive solutions, pre-treating the hair to yield an alkaline environment (i.e., hair is made more alkaline), and adding graphite, metal, conductive non-metal solids, viscous materials, and liquids, for example.

Abstract: A pair of insulated, clamping electrode electrical power output tweezers for hair removal, comprising a pair of normally closed, spaced opposed, conductive arms; a conductive tip disposed adjacent a free end of one of the pair of conductive arms; a non-conductive material substantially enclosing each one of the pair of arms; the non-conductive material defining a power transmission area disposed adjacent to and spaced from the free ends; and the power transmission area being substantially free of the non-conductive material and being sufficiently large for contacting hairs.

Abstract: A method of removing multiple hairs and inhibiting future hair growth includes the steps of applying a conductive solution to the hair, applying power for a period of time sufficient to destroy the matrix area of the hair, and allowing the treated hair to either be removed immediately or to stay in the skin for a period of time sufficient for the chemical reaction induced at the matrix area to continue long enough to destroy the matrix area and prevent regrowth of the hair. The hair removal is accomplished by use of a spring having at least two coils which are movable into engagement with each other. The two coils are configured for engaging and grasping hairs. When the coils clamp an engaged hair, and then moved relative to the skin, the hair is removed thereby. A device particularly suited for carrying out the invention includes coils which can be moved away from and toward each other for engaging hairs to be removed.

Abstract: An electrolysis machine which uses a plurality of probes each of which is to be insertable in conjunction with a hair follicle to effect removing of a hair. The probes are mounted on an arm unit which is adjustably movable to a multitude of different positions relative to a base unit which is fixedly located on a supporting surface. An electrolysis machine produces both direct current and a radio frequency with the user being able to select just the direct current or the direct current combined with the radio frequency in the performing of the destruction of the hair. The current emitted to effect the destruction of the hair is slowly raised (over a two second time period) to a level that is preset by the operator.

Abstract: The invention features a method of removing a hair, involving mechanically or chemically removing the hair to expose the follicle of the hair, and then treating the follicle to inhibit its ability to regenerate a hair. Removing the hair facilitates the uptake of a follicle-inactivating compound and thus allows for long-term inhibition of hair growth.