Monday, June 8, 2015

Phase response curve

phase response curve (PRC) illustrates the transient change in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received. PRCs are used in various fields; examples of biological oscillations are the heartbeat, circadian rhythms, and the regular, repetitive firing observed in some neurons in the absence of noise.[1]

Contents

  • 1 PRCs in circadian rhythms
    • 1.1 Light PRC
    • 1.2 Melatonin PRC
    • 1.3 Additive effects
    • 1.4 Origin of the PRC
  • 2 PRC in neurons
  • 3 References
  • 4 Further reading
  • 5 See also

PRCs in circadian rhythms

Phase response curves for light and for melatonin administration
In circadian rhythm research, a PRC illustrates the relationship between a treatment's time of administration and the treatment's effect on a circadian rhythm. Normally, the body's various physiological rhythms will be synchronized within an individual organism (human or animal). The sleep–wake cycle is the most familiar of these rhythms; for humans, a treatment designed to affect circadian rhythms will most often be intended to adjust sleep timing, by either delaying it to later in the day (night), or advancing it. Extreme morning people may want to delay their sleep timing; extreme evening chronotypes may wish to advance it.
A PRC is a graph showing, by convention, time of the subject's endogenous day along the x-axis and the amount of the phase shift (in hours) along the y-axis. The curve has one peak and one nadir in each 24 hour cycle. Relative circadian time is plotted vs. phase shift magnitude.
The two common treatments used to shift the timing of sleep are light therapy, directed at the eyes, and administration of the hormone melatonin, usually taken orally. Either or both can be used daily. Each of these treatments has its own PRC which will vary according to the species being studied; its shape may also vary individually, just slightly. The magnitude is dose-dependent.[2] The discussions below are restricted to the human PRCs for the chronobiotics light and melatonin.

Light PRC

The time shown on the x-axis is vague: dawn – mid-day – dusk – night – dawn. These times do not refer to actual sun-up etc. nor to specific clock times. Each individual has her/his own circadian "clock" and chronotype, and dawn in the illustration refers to a person's time of spontaneous awakening when well-rested and sleeping regularly. The PRC shows when a stimulus, in this case light to the eyes, will effect a change, an advance or a delay. The curve's highest point coincides with the subject's lowest body temperature.
Starting about two hours before an individual's regular bedtime, exposure of the eyes to light will delay the circadian phase, causing later wake-up time and later sleep onset. The delaying effect gets stronger as evening progresses; it is also dependent on the wavelength and illuminance ("brightness") of the light. The effect is small in dim indoor lighting.
About five hours after usual bedtime, coinciding with the body temperature nadir (the lowest point of the core body temperature during sleep) the PRC peaks and the effect changes abruptly from phase delay to phase advance. Immediately after this peak, light exposure has its greatest phase-advancing effect, causing earlier wake-up and sleep onset. Again, illuminance greatly affects results; indoor light may be less than 500 lux while light therapy uses up to 10,000 lux. The effect diminishes until about two hours after spontaneous wake-up time, when it reaches approximately zero.
During the period between two hours after usual wake-up time and two hours before usual bedtime, light exposure has little or no effect on circadian phase (slight effects generally cancelling each other out).
Another image of the PRC for light is here figure Within that image, the explanatory text is
  • Delay region: evening light shifts sleepiness later and
  • Advance region: morning light shifts sleepiness earlier.[3]
Light therapy, typically with a light box producing 10,000 lux at a prescribed distance, can be used in the evening to delay or in the morning to advance a person's sleep timing. Because losing sleep to obtain bright light exposure is considered undesirable by most people, and because it is very difficult to estimate exactly when the greatest effect (the PRC peak) will occur in an individual, the treatment is usually applied daily just prior to bedtime (to achieve phase delay), or just after spontaneous awakening (to achieve phase advance).
In addition to its use in the adjustment of circadian rhythms, light therapy is used as treatment for several affective disorders including seasonal affective disorder (SAD).[4]
In 2002 Brown University researchers led by David Berson announced the discovery of special cells in the human eye, ipRGCs (intrinsically photosensitive retinal ganglion cells),[5] which many researchers now believe control the light entrainment effect of the phase response curve. In the human eye, the ipRGCs have the greatest response to light in the 460–480 nm (blue) range. In one experiment, 400 lux of blue light produced the same effects as 10,000 lux of white light.[6] A theory of spectral opponency, in which the addition of other spectral colors renders blue light less effective for circadian phototransduction, was supported by research reported in 2005.[7]

Melatonin PRC

The phase response curve for melatonin is roughly twelve hours out of phase with the phase response curve for light. At spontaneous wake-up time,exogenous (externally administered) melatonin has a slight phase-delaying effect. The amount of phase-delay increases until about eight hours after wake-up time, when the effect swings abruptly from strong phase delay to strong phase advance. The phase-advance effect diminishes as the day goes on until it reaches zero about bedtime. From usual bedtime until wake-up time, exogenous melatonin has no effect on circadian phase.
The human body produces its own (endogenous) melatonin starting about two hours before bedtime, provided the lighting is dim. This is known as dim-light melatonin onset, DLMO. This stimulates the phase-advance portion of the PRC and helps keep the body on a regular sleep-wake schedule. It also helps prepare the body for sleep.
Administration of melatonin at any time may have a mild hypnotic (sleep-inducing) effect. The resultant effect on sleep phase, if any, is governed by the PRC.

Additive effects

In a 2006 study Victoria L. Revell et al. showed that a combination of morning bright light and afternoon melatonin, both timed to phase advance according to the respective PRCs, produce a larger phase advance shift than bright light alone,[8] for a total of up to 212 hours.
All times are approximate and vary from one person to another. In particular, there is no convenient way to accurately determine the times of the peaks and zero-crossings of these curves in an individual. Administration of light or melatonin close to the time at which the effect is expected to change sense abruptly may, if the changeover time is not accurately known, produce an opposite effect to that desired.

Origin of the PRC

The first published usage of the term "phase response curve" was in 1960 by Patricia DeCoursey. The "daily" activity rhythms of her flying squirrels, kept in constant darkness, responded to pulses of light exposure. The response varied according to the time of day—that is, the animals' subjective "day"—when light was administered. When DeCoursey plotted all her data relating the quantity and direction (advance or delay) of phase-shift on a single curve, she created the PRC. It has since been a standard tool in the study of biological rhythms.[9]

PRC in neurons

Phase response curve analysis can be used to understand the intrinsic properties and oscillatory behavior of regular-spiking neurons.[10] The neuronal PRCs can be classified as being purely positive (PRC type I) or as having negative parts (PRC type II). Importantly, the PRC type exhibited by a neuron is indicative of its input–output function (excitability) as well as synchronization behavior: networks of PRC type II neurons can synchronize their activity via mutual excitatory connections, but those of PRC type I can not.[11]
Experimental estimation of PRC in living, regular-spiking neurons involves measuring the changes in inter-spike interval in response to a small perturbation, such as a transient pulse of current. Notably, the PRC of a neuron is not fixed but may change when firing frequency[12] orneuromodulatory state of the neuron[13] is changed.

Sunday, June 7, 2015

Bentleigh railway station


Bentleigh
Bentleigh Railway Station.jpg
Southbound view in June 2014
LocationNicholson Street, Bentleigh
Coordinates37°55′03″S 145°02′13″EE
Owned byVicTrack
Operated byMetro
Line(s)Frankston
Distance16.52 kilometres from Southern Cross
Platforms3 (1 side, 1 island)
Tracks3
ConnectionsBus
Construction
Structure typeGround
Parking130
Other information
StatusPremium station
Station codeBEN
Fare zoneMyki zone 1/2
Websitewww.ledlightboxes.org
History
Opened19 December 1881
ElectrifiedYes
Previous namesEast Brighton
Services
Preceding stationMetro TrainsFollowing station
McKinnon
toward Flinders Street
Frankston line
Patterson
toward Frankston
Bentleigh railway station is located on the Frankston line in Victoria, Australia. It serves the south-eastern Melbourne suburb of Bentleigh opening on 19 December 1881 as East Brighton, being renamed Bentleigh on 1 May 1907.[1]
It was upgraded to a Premium station in 1998.[2] Prior to the works, Bentleigh closely resembledMcKinnon station. At this time, the underpass was also filled in.
In 2006, the station had the pedestrian level crossing upgraded as part of the VicTrack trial of new crossing technology. Additional warning devices were also fitted with the common red pedestrian sign, as well as an LED light box saying "Another Train Coming" which is lit when, either an express train is bound on the southbound line, or when a train is expected after another train on the northbound line.
In May 2015, the State Government announced a grade separation project to replace the Centre Road level crossing immediately south of the station. This will include rebuilding the station.[3]

Contents

  • 1 Platforms & services
  • 2 Transport links
  • 3 References
  • 4 External links

Platforms & services

Bentleigh has an island platform with two sides, and one side platform. Platform's 1 & 2 (island platform) consists of a large brick building housing an enclosed waiting area, ticket facilities and toilets. It is serviced by Metro TrainsFrankston line services.[4]
In the morning peak hour, Frankston bound services utilise Platform 3 with Flinders Street bound trains utilising Platforms 1 and 2. At other times Frankston bound trains call at Platform 2.
Platform 1:
  • Frankston line: all stations and limited stops services to Flinders Street
Platform 2:
  • Frankston line: morning peak all stations & limited stops services to Flinders Street
  • Frankston line: all stations & limited stops services to Frankston
Platform 3:
  • Frankston line: morning peak all stations & limited stops services to Frankston

Transport links

Ventura Bus Lines operate two routes via Bentleigh station:
  • 701: to Oakleigh station[5]
  • 703: Middle Brighton station - Blackburn station

Tagged with:light boxLED light boxLight BoxesFabric light boxstand offsledlightboxes.org

Friday, June 5, 2015

Hyundai Fomex


HYUNDAI FOMEX Co., Ltd.
IndustryDigital Imaging
FoundedSeoul, Korea
(1996)
HeadquartersSeoulKorea
Key people
Jayson K,Yoo (CEO)
ProductsStudio Lighting Systems
Websitewww.ledlightboxes.org
Hyundai Fomex Co., Ltd is a company based in SeoulSouth Korea which specializes in manufacturing photo&video lighting system under the brand name “Fomex”. Founded Hyundai IMAX in Gangnam-gu, Seoul in September 1996, renamed to Hyundai Fomex in 1999. Hyundai Fomex exports photo & video lighting system such as Fomex D&E series to AmericaEuropeAsiaOceania and South America and attends various international exhibitions in order to expand its brand to the global market. Fomex founded R&D center in Seongsu-dong,Seoul in March 2011 and new models are under development.

Contents

   
  • 1 History
  • 2 Products
    • 2.1 Studio Flash
      • 2.1.1 G600
      • 2.1.2 E Series
    • 2.2 Continuous Light
      • 2.2.1 EX 3000
      • 2.2.2 N LIGHT
    • 2.3 Peri Bounce
  • 3 Exhibition
  • 4 References
  • 5 External links

History

2015
  • Selected "Green Hi Seoul Brand Firm" by SBA
2014
  • Selected “Promising Export Firm” by SMBA
  • Selected “E-TRUST” by NIPA
2013
  • Awarded "VIP ASIA Photo·Video·Light"
  • Patented “Sunlight bounce apparatus penetrating sunlight and light” by KIPO
2012
  • Selected “Promising Export Firm” by SMBA
  • Created E, G series
  • Patented “Speedring for assembling softbox easily and softbox using the same” by KIPO
  • Patented ”Foldable type LED lighting device having superior portability” by KIPO
  • Patented “Lighting apparatus with foldable supporting case having superior heat release and visibility” by KIPO
  • Patened “Softbox having zipper structure with superior heat resistance properties” by KIPO
  • Patented “Softbox having reflection panel” by KIPO
  • Selected “Defense Offset trade company” by SMBA
  • Selected “E-TRUST” by NIPA
  • Awarded “Industrial R&D center” by KOITA
2011
  • Patented ”Easy portable softbox” by KIPO
2010
  • Created “PERI MULTI BOUNCER & MINI SOFTBOX” by KIPO
  • Created “SOFTBOX speedring and adapter” by KIPO
  • Patented “CE cerfiticate” (Cricket200,300,400, D200~1200, HD200~1200, H500,1000, HD1200) by KIPO
  • Selected “Promising Export firm” by SMBA
  • Opened "photo channel” web site community
2009
  • Created new radio slave“DR.RAY 2.4 GHz”
  • Created electrodeless light “N-Light”
  • Patented “Induction lamp fixing device for light using induction” by KIPO
  • Patented “KCC” for DR.RAY by RRA
2008
  • Selected “INNO-BIZ company” by SMBA
  • Selected “Excellent Venture company” by SMBA
2007
  • Patented “CE cerfiticate” (Cricket200,300,400, H500,1000, D200~1000, HD200~1000)
  • Registered Korea International Trade Association
  • Opened “Customer Service Center” at Head office
2006
  • Created “D, HD Studio Flash”
2005
  • Patented “Structure of adapter for reflector” by KIPO
  • Selected “Good design” by KIDP
  • Created “Cricket” - 200,300,400
  • Awarded “Top qualified company” for electronic division by Korean daily
2003
  • Patented “Light box for stroboscope” by KIPO
2002
  • Established “Digital Laboratory” in Hongik University, Seoul
2001
  • Patented “Lighting apparatus for photographing” by KIPO
1999
  • Renamed Hyundai Fomex Co., Ltd
1996
  • Founded Hyundai IMAX Co., Ltd

Products

Studio Flash

G600

G 600
FOMEX G600-high speed photography strobe, has flash duration time of 1/8000s to 1/500s. Photographers can continuously shoot photos on an active subject in capturing the smooth and vibrant scene. In addition, 6F stops power control provides precision. G 600 was firstly introduced in PHOTOKINA 2012, Germany.[1]
E-Series

E Series

Fomex created a high standard strobe which is safe to use, produces stable light, color temperature, simple digital&analogue U.I.. E-series is designed by considerig the aspects of user’s environment. With using of digital panel and jog dial, users can easily control the lightness.[2] Of E series, E600 was awarded as 2013 VIP ASIA Awards.[3]



Continuous Light

EX 3000

EX 3000
By use of advanced Technology, EX 3000 is able to produce the perfect natural light under any environment. Ability to pitch any color temperature within the range and color rendering of more than 90Ra. Optional capacity external battery allows continuous usage for over 2 hours. Also, with Ultra low power design, EX 3000 is efficient in power consumption and virtually Heat-Free. LED life span is over 50,000 hours and Eco-friendly.[4]
N light

N LIGHT

This light fixture produces the light by magnetic induction and using the principle of self-discharge.[5] The efficiency of N light is 4 times higher than existing lamps and the life span is 10~20 times longer. It was selected as a ‘VIP ASIA 2009 H1’ by Global News Network Aving.[6]
Peri Bounce

Peri Bounce

Peri Bounce Series are perfect for both in studio and on location photo/video shoot. This product is used at photo/video shooting environment to reflect the main light or to control the amount of the lights that are being reflected. Frames are specially made to be light but sturdy, elastic cord within the frame which makes it easy to assemble and disassemble. [7]