#Azimuth 163

[thorsenmark]

High Adventure in Joshua Tree National Park by Mark Stevens Via Flickr: While at the Keys View in Joshua Tree National Park with a view looking to the south-southeast across ridges and peaks of the Joshua Tree Ranges and Little San Bernardino Mountains. My thought on composing this image was to take advantage of the layering present with the ridges. Far off in the distance is the Salton Sea, along with other points in the San Jacinto Mountains. I felt that angling my Nikon SLR camera slightly downward would help to bring out more of a sweeping view across this national park and southern California landscape, while also minimizing what I felt was a more negative space with the blue skies above.

[writingbiologi]

THE PRECISION OF DIRECTIONAL HEARING IN THE BARN OWL

ABSTRACT The barn owl can accurately locate prey due to morphological adaptations. The asymmetry of the ears as well as the facial ruff aids them in precisely locating a sound source in elevation, whereas the distance between the ears allows them to locate sounds in azimuth.

 INTRODUCTION

Many owls are known for their nocturnal hunting behaviour. To localise and catch prey, often small mammals, in the dark with little to no light, the owls need an acute sense of hearing and they require a precise directionality to do so. The barn owl (Tyto alba) for example can locate a sound source within one to two degrees in azimuth as well as elevation (Knudsen, 1981). When it comes to studying the precision of the directional hearing in owls, the barn owl is one of the most well studied owls and will be the main focus of this review.

MORPHOLOGY

To understand how the barn owl has such a precise sense of directional hearing, it is necessary to understand the morphology of the owl’s ears and facial feathers. The barn owl’s ears are asymmetrical (Fig. 1) with the left ear located slightly higher than the right with the ear opening pointing downward. The right ear on the other hand is located slightly below the left ear with the ear opening pointed upwards. This allows the owl to better hear sounds coming from below azimuth in the left ear and sounds coming from above azimuth in the right ear (Knudsen, 1981), allowing the barn owl to determine the elevation to a certain degree. The asymmetry, however, is only for the ear openings, without affecting the symmetry of the middle and inner ear (Konishi, 1973).

In azimuth, it is the physical separation of the ears and distance between them which can aid in the detection of sound as the ear closest to the sound will perceive the sound to be louder compared to the ear furthest away (Knudsen, 1981).

Figure 1. The asymmetrical ears of the barn owl. Notice how the left ear is located slightly higher on the head than the right ear (from Knudsen, 1981).

The facial feathers, also known and henceforth referred to as the facial ruff, act as a sound collector (von Campenhausen & Wagner, 2006) and is efficient in reflecting high frequency sounds (Knudsen, 1981). The facial ruff consists of two types of feathers (Fig. 2); the auricular feathers and the reflector feathers. The auricular feathers are the main component of the facial ruff. They are acoustically transparent due to the reduced ramification (the feathers have a lower density of barbs branching of the rachis), but are efficient in keeping the ruff clean. The reflector feathers form the edge of the ruff. These feathers are densely ramified and are therefore able to control the path of the sound and direct it to the ear openings (von Campenhausen & Wagner, 2006). There is a third type of feather on the head of the barn owl and everywhere else on the owl’s body except for the ruff; the contour feathers, however, they serve no purpose in sound localisation (von Campenhausen & Wagner, 2006).

Figure 2. The three types of feathers found on the barn owl’s head. (Left) the auricular feathers with reduced ramification and is acoustically transparent, helping to keep the ruff clean. (Right) the reflector feather with dense ramification, acting as a sound funnel directing the sound to the ear opening. (Top) the contour feather with no acoustic specialisation (from von Campenhausen & Wagner, 2006).

DIRECTIONAL CUES IN AZIMUTH

To determine the location of a sound in azimuth, the barn owl uses the interaural time difference which is the time difference between the arrival of the sound to the closest and furthest ear respectively (Coles & Guppy, 1988; von Campenhausen & Wagner, 2006). The highest difference in time delay is when the sound arrives from the side, whereas there will be no difference in time when the sound appears from the front (Knudsen, 1981).

Barn owls rely on both ears to accurately locate prey (Knudsen, 1981). Experiments with ear occlusion have shown that occluding one ear of the owl induces large errors in accurate location of the sound source (Konishi, 1973; Knudsen & Konishi, 1979; Knudsen, 1981). Plugging one ear causes the owl to miss the target as it turns to the opposite side of the plugged ear. This makes sense as the intact ear would perceive the sound as being louder than the occluded ear (Konishi, 1973). It is not insignificant whether the left or right ear is occluded as there will be slight differences between the errors committed. Depending on which ear is occluded the owl will either overestimate or underestimate the location of the target; plugging the left ear the owl will strike to the right and beyond the target, whereas plugging the right ear will cause the owl to strike to the left and short of the target (Knudsen & Konishi, 1979).

DIRECTIONAL CUES IN ELEVATION

As mentioned earlier, the facial ruff is essential for the barn owl to accurately locate sounds and is most important in locating sounds in elevation as the ruff has little significance in azimuth. The ruff is directed in slightly different directions depending on the left and right side; slightly downward to the left and slightly upward to the right; if the sound moves up it will become louder in the right ear and more muffled in the left ear, whereas if the sound moves down, it will be louder in the left. This provides accurate information in elevation as the perceived intensity can swiftly change with elevation (Knudsen, 1981).

Experiments have been performed where the facial ruff was removed to examine how the precision of the owl’s directionality was affected. A common conclusion for all experiments was that if the facial ruff was removed, it would significantly reduce the directional accuracy of the owl’s hearing and induce large elevational errors (Knudsen & Konishi, 1979; Coles & Guppy, 1988; von Campenhausen & Wagner, 2006). However, the directionality in azimuth was unperturbed by the removal of the facial ruff, lending further evidence that interaural time difference is more important in azimuth (Knudsen & Konishi, 1979) as the barn owls are able to orient themselves in the horizontal plane but unable to identify the vertical position of the sound (Knudsen, 1981).

One experiment performed by Konishi (1973) suggested the facial ruff acted like a sound amplifier by gathering sound from a wide area and focusing it onto a smaller area. This hypothesis arose because the owl performed poorly in locating the target sound by landing short of it. Konishi then increased the sound level with 10 decibels and the owl’s accuracy improved.

Another experiment by von Campenhausen & Wagner (2006) further proved that removing the reflector feathers had the greatest impact on the barn owl’s ability to accurately locate sounds in elevation. The effect of the reflector feathers on the ears, causes them to be more spatially selective, more sensitive, and increase directionality (von Campenhausen & Wagner, 2006), which proves the importance of the facial ruff to the barn owl.

OPTIMAL FREQUENCIES

The directional sensitivity of the barn owl’s ears depends on the reflection of sound. At low frequencies, the reflection of sound is reduced and because there is only a gradual change in low frequencies with changing direction, the comparison of low frequency intensities will only provide a crude spatial cue and no cue in elevation (Knudsen, 1981). The ruff therefore does not have any major effect on the directionality of elevation at low frequencies (Knudsen & Konishi, 1979). For barn owls, low frequencies are <4 kHz (Knudsen & Konishi, 1979). As the frequency increases (≥4 kHz), the ruff will act like an efficient sound reflector and cause the ears to be more sensitive to sounds coming from above (right ear) or below (left ear) the horizontal plane of the owl (Knudsen & Konishi, 1979). Even if the barn owl can hear frequencies ranging from 100 Hz to 12 kHz (Knudsen, 1981), experiments have revealed that the optimal frequencies for the owl to gain any clues for accurately locating sound sources lies between 5 to 9 kHz (Konishi, 1973; Knudsen & Wagner, 1979; Coles & Guppy, 1988). The spatial resolution of the barn owl’s directional hearing therefore increases with higher frequencies (Knudsen & Konishi, 1979), but above 9 kHz the sensitivity begins to decline (Konishi, 1973; Coles & Guppy, 1988).

ANTHROPOGENIC NOISE

Barn owls, and other owls, are acoustically specialised predators. As is evident in this review, barn owls heavily relies on it hearing to catch prey. As the world becomes more urbanised, it is inevitable that anthropogenic noise will present an issue for barn owls and their hunting success. Anthropogenic noise is mainly <10 kHz, which causes an overlap in frequency with the noise made by prey animals. This overlap can force the owls to abandon otherwise favourable hunting grounds or reduce their condition as it will become more difficult for the owls to forage (Mason et al., 2016).

CONCLUSION

The barn owl’s ability to accurately locate prey is due to morphological adaptations optimising the owl’s hearing. The asymmetry of the ears as well as the facial ruff aids them in precisely locating a sound source in elevation, whereas the distance between the ears allows them to locate sounds in azimuth. Further, the facial ruffs capacity to reflect, direct, and amplify high frequency sounds between 5-9 kHz further increases the directionality of the barn owl’s hearing.

For accurate location of sound sources the barn owl needs both ears and complete facial ruff. Occluding an ear or removal of the ruff greatly diminishes the owl’s ability to locate sounds and by extension catch prey.

Not only do alterations to ears and facial ruff decrease directionality, but so does anthropogenic noises.

REFERENCES

Coles, R.B. and Guppy, A. 1988. Directional hearing in the barn owl (Tyto alba). J Comp Physiol A 163: 117-133.

Knudsen, E.I. 1981. The hearing of the barn owl. Sci Am 245: 113-125.

Knudsen, E.I. and Konishi, M. 1979. Mechanisms of sound localization in the barn owl (Tyto alba). J Comp Physiol A 133. 13-21.

Konishi, M. 1973. How the owl tracks its prey. Amer Sci 100: 494-503.

Mason, J.T., McClure, C.J.W. and Barber, J.R. 2016. Anthropogenic noise impairs owl hunting behaviour. Biol Cons 199: 29-32.

von Campenhausen, M. and Wagner, H. 2006. Influence of the facial ruff on the sound-receiving characteristics of the barn owl’s ears. J Comp Physiol A 192: 1073-1082.

[hillcountrytimes]

Parnassus Investments Cut Motorola Solutions (MSI) Stake By $147.18 Million; Vulcan Value Partners Lifted Navigant Consulting (NCI) Stake By $733,647

Vulcan Value Partners Llc increased Navigant Consulting Inc (NCI) stake by 2.5% reported in 2017Q2 SEC filing. Vulcan Value Partners Llc acquired 38,613 shares as Navigant Consulting Inc (NCI)’s stock declined 15.71%. The Vulcan Value Partners Llc holds 1.58 million shares with $31.28 million value, up from 1.54M last quarter. Navigant Consulting Inc now has $878.91M valuation. The stock decreased 0.26% or $0.05 during the last trading session, reaching $19.14. About 329,821 shares traded or 22.52% up from the average. Navigant Consulting, Inc. (NYSE:NCI) has risen 27.76% since December 2, 2016 and is uptrending. It has outperformed by 11.06% the S&P500.

Parnassus Investments decreased Motorola Solutions Inc. (MSI) stake by 23.38% reported in 2017Q2 SEC filing. Parnassus Investments sold 1.71M shares as Motorola Solutions Inc. (MSI)’s stock rose 1.92%. The Parnassus Investments holds 5.61M shares with $486.44M value, down from 7.32M last quarter. Motorola Solutions Inc. now has $15.07 billion valuation. The stock decreased 1.15% or $1.08 during the last trading session, reaching $93.03. About 1.00M shares traded or 21.77% up from the average. Motorola Solutions, Inc. (NYSE:MSI) has risen 17.62% since December 2, 2016 and is uptrending. It has outperformed by 0.92% the S&P500.

Investors sentiment decreased to 1.03 in Q2 2017. Its down 0.14, from 1.17 in 2017Q1. It worsened, as 33 investors sold MSI shares while 163 reduced holdings. 61 funds opened positions while 140 raised stakes. 134.09 million shares or 0.79% more from 133.03 million shares in 2017Q1 were reported. Arizona State Retirement System reported 0.08% in Motorola Solutions, Inc. (NYSE:MSI). Criterion Cap Mngmt Lc accumulated 690,757 shares. Texas Permanent School Fund reported 45,930 shares. Amp Cap Investors holds 0.02% or 44,387 shares in its portfolio. Investment Advsrs reported 0.02% in Motorola Solutions, Inc. (NYSE:MSI). 52 were accumulated by Wfg Limited Partnership. Fukoku Mutual Life Ins Co owns 1,628 shares. Spark Inv Mngmt Lc holds 0.01% or 2,500 shares in its portfolio. 792 are owned by Pinnacle Fincl Ptnrs. Thrivent Fincl For Lutherans has 0% invested in Motorola Solutions, Inc. (NYSE:MSI) for 6,290 shares. Cognios Capital Ltd Limited Liability Company holds 0.84% or 27,785 shares in its portfolio. Winfield Assocs Inc has 0% invested in Motorola Solutions, Inc. (NYSE:MSI) for 89 shares. Azimuth Cap Mgmt Lc owns 6,896 shares. Aviva Public Limited invested in 0.05% or 103,371 shares. Proshare Advsrs Limited Liability Com invested 0.04% in Motorola Solutions, Inc. (NYSE:MSI).

Analysts await Motorola Solutions, Inc. (NYSE:MSI) to report earnings on February, 1. They expect $1.97 EPS, down 0.51% or $0.01 from last year’s $1.98 per share. MSI’s profit will be $319.14M for 11.81 P/E if the $1.97 EPS becomes a reality. After $1.46 actual EPS reported by Motorola Solutions, Inc. for the previous quarter, Wall Street now forecasts 34.93% EPS growth.

Parnassus Investments increased Expeditors International Of Washington Inc. (NASDAQ:EXPD) stake by 80,000 shares to 2.18 million valued at $123.35M in 2017Q2. It also upped United Parcel Service Inc. Class B (NYSE:UPS) stake by 1.70 million shares and now owns 6.45 million shares. Danaher Corp. (NYSE:DHR) was raised too.

Among 16 analysts covering Motorola Solutions (NYSE:MSI), 11 have Buy rating, 1 Sell and 4 Hold. Therefore 69% are positive. Motorola Solutions had 37 analyst reports since August 6, 2015 according to SRatingsIntel. The rating was upgraded by BMO Capital Markets to “Outperform” on Wednesday, October 12. Jefferies maintained the shares of MSI in report on Friday, August 4 with “Buy” rating. The rating was initiated by Macquarie Research on Thursday, October 22 with “Underperform”. As per Friday, May 26, the company rating was maintained by Jefferies. The rating was upgraded by Bernstein on Tuesday, February 23 to “Outperform”. The rating was maintained by Cowen & Co with “Hold” on Friday, August 4. Deutsche Bank maintained it with “Hold” rating and $65 target in Friday, December 4 report. The firm earned “Hold” rating on Monday, December 7 by Jefferies. The rating was upgraded by Macquarie Research on Wednesday, February 24 to “Neutral”. The firm has “Buy” rating given on Tuesday, May 30 by Northcoast.

Among 4 analysts covering Navigant Consulting (NYSE:NCI), 2 have Buy rating, 1 Sell and 1 Hold. Therefore 50% are positive. Navigant Consulting had 5 analyst reports since July 31, 2015 according to SRatingsIntel. SunTrust maintained it with “Hold” rating and $20.0 target in Wednesday, October 18 report. As per Friday, July 31, the company rating was upgraded by Avondale. Barrington Research upgraded Navigant Consulting, Inc. (NYSE:NCI) on Monday, November 2 to “Outperform” rating. Zacks downgraded the shares of NCI in report on Monday, September 7 to “Sell” rating. The stock of Navigant Consulting, Inc. (NYSE:NCI) earned “Sell” rating by Zacks on Monday, September 21.

Investors sentiment decreased to 1.12 in 2017 Q2. Its down 0.26, from 1.38 in 2017Q1. It dropped, as 27 investors sold NCI shares while 49 reduced holdings. 20 funds opened positions while 65 raised stakes. 41.99 million shares or 3.37% less from 43.45 million shares in 2017Q1 were reported. Metropolitan Life Ins New York has 32,321 shares. 456,100 were accumulated by Bridgeway Cap Mngmt Incorporated. Teachers Retirement Sys Of The State Of Kentucky accumulated 16,900 shares or 0% of the stock. Massachusetts-based State Street has invested 0% in Navigant Consulting, Inc. (NYSE:NCI). Comerica Bancorporation owns 106,906 shares. 14,173 were reported by Stevens Mngmt Lp. Pillar Pacific Capital Mngmt Ltd Co has invested 0.05% of its portfolio in Navigant Consulting, Inc. (NYSE:NCI). Blackrock holds 0.01% in Navigant Consulting, Inc. (NYSE:NCI) or 5.67M shares. Td Asset invested in 12,400 shares or 0% of the stock. Alliancebernstein LP reported 57,924 shares. 2,231 were accumulated by Old Mutual Global (Uk) Ltd. First Trust Advisors Limited Partnership has 85,957 shares for 0% of their portfolio. 42 are owned by Sei Investments. Arrowstreet Cap Lp owns 412,893 shares. State Bank Of America De reported 82,076 shares.

The post Parnassus Investments Cut Motorola Solutions (MSI) Stake By $147.18 Million; Vulcan Value Partners Lifted Navigant Consulting (NCI) Stake By $733,647 appeared first on Stock Market News | HillCountryTimes | Get it Today.

from Stock Market News | HillCountryTimes | Get it Today https://www.hillcountrytimes.com/2017/12/02/parnassus-investments-cut-motorola-solutions-msi-stake-by-147-18-million-vulcan-value-partners-lifted-navigant-consulting-nci-stake-by-733647/

[michel05132]

  Acquisition date 30 August 2016 Local Mars time: 15:21 Latitude (centered) -0.337° Longitude (East) 319.298° Range to target site 271.0 km (169.4 miles) Original image scale range 54.2 cm/pixel (with 2 x 2 binning) so objects ~163 cm across are resolved Map projected scale 50 cm/pixel and North is up Map projection Equirectangular Emission angle: 5.2° Phase angle: 56.6° Solar incidence angle 51°, with the Sun about 39° above the horizon Solar longitude 213.5°, Northern Autumn North azimuth: 97° Sub-solar azimuth: 349.0° JPEG Black and white

(via HiRISE | Chaotic Terrain in Xanthe Terra (ESP_047317_1795))

[thorsenmark]

Talk About a Snowy Day in Joshua Tree National Park! by Mark Stevens Via Flickr: In Joshua Tree National Park while at the Hidden Valley Nature Trailhead with a view looking to the south-southeast. The setting is with a more distant rock formation that was getting to the point of being almost obscured by the snow falling. Not a typical site I expected to see while visiting a national park, but definitely a very nice one to come across, no doubt!

[thorsenmark]

Beginning My Exploration of Joshua Tree National Park by Mark Stevens Via Flickr: While just outside the main west park entrance with a view looking to the southeast across the mountain desert landscape present in this part of Joshua Tree National Park.

[thorsenmark]

Talk About a Snowy Day in Joshua Tree National Park! by Mark Stevens Via Flickr: In Joshua Tree National Park while at the Hidden Valley Nature Trailhead with a view looking to the south-southeast. The setting is with a more distant rock formation that was getting to the point of being almost obscured by the snow falling. Not a typical site I expected to see while visiting a national park, but definitely a very nice one to come across, no doubt!

[thorsenmark]

A Revisit to a Black and White Recipe Preset I Made About 12 Years Ago by Mark Stevens Via Flickr: I captured this image not long after taking off out of Austin on a flight to San Jose for a trip that would eventually take me to Pinnacles National Park. This is an airplane window view, looking generally to the south, with the one of the airplane wings as we started to fly above some clouds. That was my thought on composing this image. As for the recipe preset, it was one that I came across and made while reading Jason Odell's book on Capture NX2. I experimented with a few things as I worked with the black and white settings I came across in the book. One of the things that I did on that recipe was to make the shadowed portions of the clouds darker, while the ones caught in sunlight much brighter. Another was working with the levels and curves to make adjustments to the individual red, green, and blue values. I am now working with DxO PhotoLab 6 and had to find equivalent ways to make that look. Still some to work on but a nice try again after so many years.

[thorsenmark]

Getting My National Park Fix in New River Gorge National Park & Preserve by Mark Stevens Via Flickr: While standing on the Stone Cliff Bridge and a view looking to the south upstream with the New River flowing by. I went with a wider angle view in order to capture and include more of the surrounding ridgelines and mountains of river valley. I felt that would let the river be that wide, leading line into the image. I also angled my Nikon SLR camera slightly downward to create a sweeping view across this river valley. The blue skies above would then be that color contrast to complement the yellows and greens in the lower portion of the image.

[thorsenmark]

Rolling Hills to a Distant Horizon in Wind Cave National Park by Mark Stevens

[thorsenmark]

Getting My National Park Fix in New River Gorge National Park & Preserve by Mark Stevens Via Flickr: While standing on the Stone Cliff Bridge and a view looking to the south upstream with the New River flowing by. I went with a wider angle view in order to capture and include more of the surrounding ridgelines and mountains of river valley. I felt that would let the river be that wide, leading line into the image. I also angled my Nikon SLR camera slightly downward to create a sweeping view across this river valley. The blue skies above would then be that color contrast to complement the yellows and greens in the lower portion of the image.

[thorsenmark]

Ponderosa Pines and Rolling Hills Along the Rankin Ridge Nature Trail (Wind Cave National Park) by Mark Stevens Via Flickr: A view from the main overlook along Rankin Ridge in Wind Cave National Park with a view looking to the south-southeast. I finished up post-processing work in Capture NX2 by adding a few CEP filters (Low Key, Polarization and Graduated Neutral Density) for the final image.

[thorsenmark]

Love is All! But Being Around Some Tall Trees Is Also Pretty Sweet! (Mammoth Cave National Park) by Mark Stevens Via Flickr: Part of some daydreams going through my mind while walking some of the trails to the west of the Visitor Center in Mammoth Cave National Park. In this area, there was this seemingly perfect convergence of trees above me, so composing the image was a matter of rotating myself around until I could capture that angle of trees coming together. Metering this image was a little trickier as there was a very large dynamic range with the overcast skies and more shadowed area under the tree canopy. I went with an average/mean shutter speed in Manual mode. My feeling was that if I did lose any highlights, it would have a minimal effect given there wasn't much details with the overcast skies. I could then more easily pull colors and details out in trees and leaves without using an HDR program. I worked entirely in Capture NX2 for the final image, using a Foliage, Skylight and Pro Contrast CEP set of filters.