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Resampling with Chirp Z
Since chirp Z transform can zoom in on a specific segment of a signal's spectrum, I would think it can be used for downsampling or upsampling purposes. That is indeed the case. I did not now what to expect precisely, so I figured out by experiment how to do it.
Below is a test function consisting of two cosines with periodicity 1 and 3 in an FFT framesize of 1024 samples.
I zoom in on the spectrum with zoomfactor 2. As ever, this spectrum looks inconspicuous:
I feed this spectrum in a regular inverse FFT. What comes out, is the signal downsampled by a factor 2:
So by zooming in on the spectrum, which is in fact upsampling, the signal can be downsampled. That is funny. Of course, this downsampling was not such a difficult task. It could be done by taking away every other sample, instead of the chirp Z transform with it's two complex FFT's of double size, plus a regular inverse FFT. Therefore, I will try a weird downsampling factor like 1.5:
Such downsampling can also be done by 'fractional resampling', where you first upsample and then downsample, the factors being a ratio of relatively prime integers. That would require a lot of filtering. But, can chirp Z downsample without filtering? To check this, I add a frequency in the second half band, at harmonic 280 (Nyquist is at 512). This is my test signal:
Doing chirp Z transform with zoom factor 2.2, for example, the upsampled spectrum has a peak above the Nyquist frequency, originating from harmonic 280. That peak has no conjugate. In fact, after stretching the spectrum, nothing has a conjugate anymore.
Reverting this spectrum back to time domain, would give the signal plotted below. The high frequency comes from the peak above Nyquist. It can not be harmonic 280 since the downsampled signal has harmonics up till around 230 in the positive range. It is an alias of a frequency that was not in the original, and should be eliminited.
The solution seems simple. When we are in frequency domain anyway, a mirrorsymmetric spectrum can be computed from the first half, to get rid of aliases. The result is a bandlimited & downsampled signal:
Chirp Z can downsample with any factor, integer or not. On the previous page I zoomed in on a 1024 point spectrum with factor 200. An inverse FFT of that would give a 5 point signal, pretty useless I would think. Here is my test signal downsampled with factor 8, to have another impression:
As the signal gets sleeker, the sample value peaks grow. Apparently, the increase is proportional to the zoomafactor so this can be compensated in the normalisation. Also notice that the 'empty' range is not really empty, it even starts with a dreadful peak. A similar peak appears at the start of the downsampled signal, although it is hard to see in the plot. Let me do a magnified plot of the first 75 samples. It turns out that the signal extremes are not so perfectly interpolated at all. The distortion is probably caused by the mirrorsymmetric spectrum computation. Relevant information about the waveshape was in the second spectrum half, which is erased by that action.
I wanted to try signal upsampling as well. With that I had such weird results, until I realised the input signal should leave room for expansion. Just like the downsampled signal shrinked and thereby made room. So here is my input test signal again, but at half the length of the analysis:
I feed it into the chirp Z transform with zoom factor 0.8. That is zooming out instead of zooming in. What happens when zooming out? The opposite of zooming in. It is hard to imagine what that means. Only after experimenting, I could understand the effect. You are not seeing a segment of the spectrum, but the whole of it and even a bit more. While the spectrum shrinks, point N (1024) which is also point zero because of the periodical nature of the transform, moves leftward. In the plot below you can see how the coefficients in the lowest part of the spectrum are thereby copied to the right of this shifted N aka zero point.
Just like with zooming in, the spectrum is not mirrorsymmetric anymore. Reverting this to time domain as is, will give the signal plotted below. The upsample factor is the reciprocal of the spectrum-zoom-factor:
The high frequencies here are what they call 'image' frequencies, because they are kind of ghost image from the lower spectrum part. Images will always appear in an umsampled signal, no matter how bandlimited that signal was. With chirp Z we can get rid of the images by computing a mirrorsymmetric spectrum from it's first half, exactly like it was done for downsampled signals. Now I get this nicely stretched output:
Upsampling with chirp Z brings an extra problem that must be handled. So far, I did low frequencies and it worked well. But with high frequency content in the original, we will be bothered by conjugates. After all, with point N shifting leftward, the conjugates also shift leftward. Let me enter a high frequency to check what will happen. First do a non-zooming transform to see the original spectrum:
If I zoom out using factor 0.75, the negative frequency correlations already tresspass the middle of the analysis frame in their leftward movement:
We have to perform bandlimiting to eliminate such tresspassers. The Nyquist frequency must be tracked in it's movement. It moves like:
shiftedNyquist = Nyquist * zoomfactor
Everything between shifted Nyquist and original Nyquist must be zeroed, before computing the mirrorsymmetric spectrum.
To visually check if this works, I have to upsample the signal drastically with factor 100. Otherwise we will only see those indefinite needle bunches. On the left is the non-bandlimited output. It is diluted with zero's, which means it has alias frequencies. On the right is the bandlimited output, it has the pure transposed frequency.
This extreme upsampling was done for testing purposes, but it would not have worked if there had been frequency content below harmonic 100 of the analysis width. Such content would wrap around in the limited space. There is however also this option to rotate the whole spectrum with a frequency offset. If we make the bandlimiting function dependent on the frequency offset as well, the options for resampling increase further. Although the offset is effectuated by complex multiplication, the offset itself is not a factor but a frequency addition. To find the frequency cut off point:
shiftedNyquist = (Nyquist-frequencyoffset) * zoomfactor
Using this modification, I have checked that exactly the same result as in the above experiment can be obtained with a frequency offset of harmonic 392 (harmonic respective to analysis width) and zoom factor 0.5. But now without worries about possible distortion by low frequencies. In serious applications, this bandlimiting should probably be done with some very short curve instead of hard cut.
In this quick test of chirp Z as resampling method, I have not touched on all possibilities. But so far, I am impressed. The method is computationally intensive, on the other hand it is very flexible. Spectrum rotation for example, is 'included in the price'. You can magnify any aspect of a signal by a combination of rotation, zooming and filtering in one single process.


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Smoke from a summer wildfire is more than just an eye-stinging plume of nuisance. It's a poison to the lungs and hearts of the people who breathe it in and a dense blanket that hampers firefighting operations.
There's an atmospheric feedback loop, says University of Utah atmospheric scientist Adam Kochanski, that can lock smoke in valleys in much the same way that temperature inversions lock the smog and gunk in the Salt Lake Valley each winter. But understanding this loop, Kochanski says, can help scientists predict how smoke will impact air quality in valleys, hopefully helping both residents and firefighters alike.
Kochanski and colleagues' study appears in the Journal of Geophysical Research-Atmospheres. The work was funded by grants from the U.S. Department of Agriculture and from NASA.
Watch a video of a smoke simulation here.
In 2015, firefighters battling wildfires in northern California noticed that smoke accumulating in valleys wasn't going away. The smoke got so bad that air support had to cancel flights, slowing down the firefighting effort. "That raised the question," Kochanski says, "Why is that? Why all of a sudden, is the smoke so persistent and what keeps this very thick layer of smoke in those valleys for such a long period of time?"
Kochanski and his colleagues, including researchers from the Desert Research Institute, University of Colorado, Boulder and Harvard & Smithsonian Center for Astrophysics set out to answer those questions. Their first clue came from measurements of temperature both below and above the smoke layer. The air, they found, was warmer above the smoke than below.
Residents of the Salt Lake Valley and other bowl-shaped valleys will recognize the pattern of warmer air above colder valley air as an inversion—a reversal of the normal cooling of air with altitude. The atmospheric chemistry of Salt Lake's wintertime inversions is a little different than that of a fire inversion, but the physics are the same: Warm air rises, cold air sinks and the inversion puts a warm lid over a valley, trapping all the valley air below.
The main difference is that in case of the smoke inversions the smoke layer makes the inversion even stronger.
The feedback loop
Kochanski and his colleagues modeled the dynamics of air and smoke in valley terrain and found a feedback loop that reinforces the atmospheric inversion conditions.
"A key to this situation is the moment when the smoke appears in the atmosphere and it just does enough to block incoming solar radiation," Kochanski says. With the sun's energy blocked, the air at the ground begins to cool. "The near-surface cooling limits the mixing, enhances local inversions and leads to even higher smoke concentrations, that in turn block more solar radiation and make smoke even more persistent."
The cooling also weakens winds in the smoke-filled valley and stabilizes the atmosphere, impeding wind from breaking through and clearing out the stagnant air.
Kochanski says there are three ways out of a fire inversion. One is the settling of smoke once the fire is extinguished, allowing more light and heat to reach the ground. Another is a sufficiently large wind that can push through and mix the layers of air. A third is precipitation, as falling rain can scrub the air clean of aerosols.
"If it's business as usual and day by day you have nice sunny weather without any wind or precipitation events, well, this positive feedback loop leads to more smoke in the valleys than could be expected just based on the fire behavior alone," Kochanski says.
A new kind of forecast
Understanding the conditions that create the feedback loop help researchers predict how and when it might form or dissipate. Fire inversions will still remain a problem for firefighters, but Kochanski says that now researchers will be able to put together more accurate smoke forecasts.
"We can better tell where, how dense and how persistent the smoke is going to be," he says. "That's something that wasn't available before." Weather models will also be able to forecast air quality effects from smoke in ways they couldn't before, he adds.
The results of this study are already being integrated into the National Predictive Services Program. "When I'm talking about applications," Kochanski says. "It's not 10 years from now. It's something that we will start working on within the next couple of months."
Find the full study here.
Banner image: California Air National guardsmen from the 129th Rescue Wing perform precision water bucket drops Aug. 26, 2013, in support of the Rim Fire suppression operation at Tuolumne County near Yosemite, California. Credit: Staff Sgt. Ed Drew/USAF (_URL_

source: openbmb/Ultra-FineWeb


text: The present paper aims to identify ways to reduce pollution injected by residents in the urban wastewater network system. Two approaches are considered. The first one uses flow and pollutant calculation to test whether a polluter can easily be identified in a neighborhood. The second approach uses a survey to examine what incentive would be most effective to influence residents' behavior. Hydrodynamic simulation results show that concentration profiles at the network outlet corresponding to all possible polluters are similar and thus do not point out specific resident source of pollution. Household-level survey results show that most socio-economic and public-good-related characteristics do not play a significant role in explaining choices to discard in the home wastewater network. Apart from the nature of the waste itself, by far the belief that the respondent has about neighbors' and relatives' discarding behavior is the main driver of the choice.


text: There are union concerns that non-union forms of employee representation such as work councils may open up a second channel of communication between employees and management that would weaken union workplace representation. During World War II and the immediate post-war period, Imperial Chemical Industries (ICI) in Australia followed its British parent firm's practice of introducing works councils. It established its first works council at its Yarraville Factory in Melbourne in 1942. By 1959 there were works councils at 12 Australian factories, each with an equal number of management nominees, and representatives elected by employees. Although they could not deal with matters covered by agreements with unions, they could deal with issues such as accident prevention, factory efficiency and timekeeping. This article analyses the impact of these works councils on labour relations, particularly trade union representation, and the demise of the works councils.


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Trayless Tuesdays: Parsons Helps Public Schools Kick the Styrofoam Habit
Last Tuesday, Parsons students saw their ideas become a reality when New York City Schools Chancellor Joel I. Klein and the Department of Education's Office of SchoolFood (DOE) launched Trayless Tuesdays. This initiative stemmed from a partnership between Parsons, the grassroots organization Styrofoam Out of Schools (SOSnyc) and the DOE to reduce the use of Styrofoam trays in City public schools and replace them with biodegradable containers to reduce landfill waste.
The collaboration began last spring, when first-year Parsons students, led by faculty member and SOSnyc founder Debby Lee Cohen, created an installation for their year-end exhibition out of 1,000 used trays from public school cafeterias to raise awareness of this issue. Last summer, faculty member Jessica Corr and another group of students worked on site at PS 19 in Manhattan, where they interviewed students about creative ways to reduce waste from styrofoam trays. It is through this effort that students proposed the idea of Trayless Tuesdays. In addition, Parsons students designed a poster campaign that is used in school cafeterias to build awareness of this pilot program.
"The opportunity to work directly with public school students on important environmental issues was very exciting for our students," said Corr. "This project is part of our larger mission to empower public school students through design to make change in their communities."
Each Tuesday, polystyrene lunch trays in all city schools will be replaced with containers made of paper with a clay-based lining. Beginning April 13, schools will also begin using paper containers to serve breakfast. The DOE serves 623,039 lunches and 205,317 breakfasts daily.
"This program will help make our schools more environmentally responsible, while also sending a powerful lesson to students about the importance of sustainability," Chancellor Klein said. "Students will see first-hand that if they each make small changes in their daily lives, those efforts can add up to make a big difference for the future of our City and our planet."
As part of this ongoing partnership, earlier this month Corr and Cohen brought a group of Foundation students to the Green School, a public school in Manhattan, where they worked with public school students to develop prototype containers. These activities are being organized by the Research, Education, Arts and Design Lab at the School of Design Strategies at Parsons, co-founded by Corr.

source: HuggingFaceFW/fineweb-edu


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Volume of Prisms & Cylinders Examples
With a rectangular prism it doesn't matter which face you say is the base, your answer will turn out the same.
Let's say the bottom face is the base (the one it's sitting on):
With a triangular prism, the bases are the parallel sides (where the triangles are).
The base of this prism is a trapezoid.
A cylinder is pretty much a prism since it has parallel bases. In this example the diameter of the circle is given. As we discussed earlier, the radius is half the diameter.


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This tutorial describes how to create a few simple motions using example scripts from the Intera Motion Interface.
Motion Interface Examples
New in Intera SDK 5.2!
The Motion Interface enables the user to easily generate smooth motions for Sawyer by specifying a sequence of waypoints: the motion controller on Sawyer will automatically generate and run a trajectory that passes through the waypoints. The user can specify a variety of options, such as a maximum speed or requiring that the endpoint move on a linear path between the waypoints.
Go to Joint Angles
The go_to_joint_angles script is perhaps the simplest way to use the motion interface: it moves the arm from its current position to some target set of joint angles. Note that this script will not plan around self-collisions or obstacles.
$ rosrun intera_examples go_to_joint_angles.py -h
Print the arguments that can be passed to the script.
$ rosrun intera_examples go_to_joint_angles.py
Run the script with default parameters: move at a moderate speed to a configuration where the arm is in front of the robot with the elbow up.
$ rosrun intera_examples go_to_joint_angles.py -q -0.2 0.1 0.1 0.2 -0.3 0.2 0.4 -s 0.9 -a 0.1
Run the script with a few common arguments:
- Set the target joint angles (ordered j0 through j6):
-q -0.2 0.1 0.1 0.2 -0.3 0.2 0.4
- Set the speed ratio:
- Set the acceleration ratio:
Note that the speed and acceleration ratios are both scalar values on the range 0 to 1. The actual limits that are used in planning are equal to the maximum that each joint can achieve, scaled by the ratio. Advanced users can set kinematic limits in a more direct way using the
Go to to Cartesian Pose
The go_to_cartesian_pose moves the robot from its current position to a target pose, with the end-effector following a linear path.
$ rosrun intera_examples go_to_cartesian_pose.py -h
Display the help file for the script, listing all possible arguments.
$ rosrun intera_examples go_to_cartesian_pose.py -p 0.4 -0.3 0.18 -o 0.0 1.0 0.0 0.0 -t right_hand
Go to position (x=0.4, y=-0.3, z=0.18 meters) with a quaternion orientation (0, 1, 0, 0) and tip name right_hand. The current position or orientation will be used if only one is provided explicitly.
$ rosrun intera_examples go_to_cartesian_pose.py -q 0.0 -0.9 0.0 1.8 0.0 -0.9 0.0
Go to joint angles: 0.0 -0.9 0.0 1.8 0.0 -0.9 0.0 using default settings. If a Cartesian pose is not provided then forward kinematics will be used to compute it. If a Cartesian pose is provided, then the joint angles will be used to bias the nullspace (elbow orientation) during motion planning.
$ rosrun intera_examples go_to_cartesian_pose.py -R 0.01 0.02 0.03 0.1 0.2 0.3 -T
Jog arm with Relative Pose (in tip frame). In this case, move x=0.01, y=0.02, z=0.03 meters in translation and rotate roll=0.1, pitch=0.2, yaw=0.3 radians in orientation from the current end effector frame. The fixed position and orientation paramters will be ignored if provided.
Send Random Trajectory
The send_random_trajectory script is used to perform a random walk in joint space with the robot arm. It should be used with caution, as the robot does not know about its surroundings: make sure that there is plenty of space around the robot before running!
$ rosrun intera_examples send_random_trajectory.py -h
Provide the help file for the script, as well as default arguments.
$ rosrun intera_examples send_random_trajectory.py -n 5 -t JOINT -s 0.5
Send a random joint trajectory with 5 waypoints, using a speed ratio of 0.5 for all waypoints. Use default random walk settings.
$ rosrun intera_examples send_random_trajectory.py -d 0.1 -b 0.2
Send a random trajectory with default trajectory settings. Use a maximum step distance of 10% of the joint range and avoid the upper and lower joint limits by a boundary of 20% of the joint range.


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Indirect effects of biotic damage on photosynthesis in a forest understory.
Hamilton, Jason*,1, Aldea, Mihai2, Resti, Joseph1, Zangerl, Arthur2, Berenbaum, May2, DeLucia, Evan2, 1 Ithaca College, Ithaca, NY, _EMAIL_ University of Illinois, Urbana, IL
ABSTRACTArthropods, pathogenic bacteria, and viruses are important causes of damage to photosynthetic tissues in natural ecosystems. Calculating losses in leaf function and plant production based on leaf area removed by herbivores or infected by pathogens can greatly underestimate the actual reduction because of the indirect effects to tissues not directly injured. We quantified the indirect effects of naturally-occurring biotic damage on the photosynthetic efficiency of understory temperate hardwoods at the FACTS-1 research site (North Carolina, USA), using chlorophyll fluorescence and thermal imaging. Different damage classes( e.g. fungal, galls and chewing) produced different effects in the photosynthesis of tissue adjacent to the damage, suggesting different mechanisms of damage propagation. Halos of reduced function produced by fungal infections and galls propagated more than 2.5 times further from the visible damage, and photosynthesis was about 40% more depressed compared to chewing damage. Chlorophyll fluorescence quenching analysis revealed correlations between depressions of PSII and increases in NPQ within the areas indirectly affected by damage. However, the temperature of fungal halos was higher than the remaining leaf area, while gall halos were cooler, suggesting different mechanisms of propagation.
Key words: chlorophyll fluorescence imaging, thermal imaging, herbivory, photosynthesis
All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.


Digestive Health
Why do I have to poop right after eating?
A Answers (2)
 1 170 02-1 ask oz most embarrassing
 Dr. Oz answers a viewer's most embarrassing question and explains why she feels she has to poop immediately after eating. Learn the answer in this video.
 Helpful? 5 people found this helpful.
 - A Dr Christine M. Bouchard, MD, Colorectal Surgery, answered on behalf of HCA Virginia
 Why Do I Have To Poop Right After Eating?
 The gastrocolic reflex makes you have to poop right after eating. In this video, Christine Bouchard, MD, a colorectal surgeon at Chippenham & Johnston-Willis Hospitals, describes how the gastrocolic reflex works.
Did You See? Close
What causes burping and farting?


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OBJECTIVES: The objective of the study was to assess the metabolic risk of excessive dietary iodine intake in ewes and neonatal lambs.
DESIGN: Pregnant Šumava ewes received an experimental diet containing 3.1 mg iodine per kg of dietary dry matter in Group A (control, n=13, 6 ewes and 7 lambs) and 5.1 mg iodine per kg of dietary dry matter in Group B (experimental, n=12, 6 ewes, 6 lambs) for eight months. Iodine was administered to ewes as calcium iodate. TSH in blood serum; TT3, TT4, fT3, and fT4 in blood plasma were examined in both groups of ewes and lambs to assess the risks of iodine intake above the permitted limit, as it applies to thyroid gland activity.
RESULTS: Group B ewes showed a significant increase in TSH and TT4 only on day 1 after parturition. The highest values of TT4, TT3, and fT3 in lambs were recorded on day 1 after birth. The lowest values of fT3 and fT4 in lambs were measured on day 60 after birth with no differences observed between the groups. In lambs of Group B the lower concentration of TSH until day 3 after birth was followed by a significant increase from day 10 after birth.
CONCLUSION: Our results indicate a risk of postnatal hypothyroidism among lambs from pregnant and lactating ewes having a high iodine intake....


NCover Documentation
To enable source code highlighting:
 1. Make sure the developer generates PDBs when the source code is compiled, whether in Debug or Release mode.
 2. Make sure the path to the source files is the same as it was on the development machine. There are ways to make this work if the path is not the same, but putting the files in the same path is the easiest solution.
 3. When coverage runs, NCover.Analyze calls into the dbghelp.dll, which is the same one used by the Windows debugger, WinDbg. Tthe technique that WinDbg uses is not published in detail, but here is the basic sequence.
 a. First, look in the same directory as the DLL. This is the most common location for PDBs.
 b. Next, look in the directories that are specified by _NT_SYMBOL_PATH:
 c. Finally, if a symbol server is specified in the _NT_SYMBOL_PATH, then try to download PDBs from the symbol server.
 4. The PDBs contain the sequence point information and the location of the source files. So, if the source files are in the same location as on the machine that compiled the PDBs, then NCover 4 will be able to display the source files and highlighting.
If you still need technical assistance, we can help:
Submit A Support Ticket


The Cat's Paw Swipes Employers
In light of a recent United States Court decision, Staub v. Proctor Hospital, careful employers should consider requiring a review of lower-level managers' and supervisors' recommendations to terminate or take other actions against employees. A review allows more responsible managers to detect ill-motivated decisions that could turn into legal claims. Senior managers, uninvolved in the day-to-day supervision of an employee, can lend a degree of objectivity. They also ensure consistent application of company policies. Depending on the level of scrutiny, a second or third-level review can also ensure proper documentation identify "red flags" and assess potential risks.
Although an approval process is a good idea, it is not a vaccine against employment claims. Even if detailed policies and procedures are in place, the more senior management generally relies on lower-level employees' good faith and skill to report the relevant facts. Further, senior managers cannot always independently assess the facts that lead to a proposed decision. Some may merely "rubber stamp" a recommendation, whether because they are too busy, not trained how to review such recommendations, or because they place too much reliance on the assessment of those "on the ground."
In Staub, the Court explained that decisions tainted by discrimination cannot be cured by an innocent manager's "blessing." Whether or not the final decision maker knew of the unlawful bias, a tainted decision is attributed to the employer. This principle is known as "cat's paw" liability, as explained below.
The employer is liable for discrimination or retaliation if an unlawful bias was a motivating factor in an adverse action. This standard means employers may be liable for discrimination even if there are good reasons for taking action and the discriminatory or retaliatory animus was just one of several motivating factors.
The Staub decision combined with the "motivating factor" liability standard may frustrate employers seeking to prevent liability for unlawful decisions. What is an employer to do? The following provides an overview the "cat's paw" liability Staub affirmed. We also provide some practical steps employers can follow to minimize their potential liability.
Liability for the "Cat's Paw"
As discussed above, a plaintiff claiming unlawful discrimination or retaliation must show that the person making the decision was motivated, at least in part, by bias against plaintiff's engaging in "protected activity" (retaliation) or protected characteristics (e.g., race, religion, sex, etc).
In a cat's paw scenario, a plaintiff alleges that someone else, acting with a discriminatory motive, influenced the decision but was not ultimately responsible for the adverse action taken against the plaintiff. The term "cat's paw" comes from a 1990 court decision in which the court analogized to a fable involving a monkey and a cat. The monkey convinced the cat to reach into a fire and pull out roasting chestnuts. The monkey then took the chestnuts, leaving the cat with nothing except for a burned paw.
Thus, under the cat's paw theory, a lower-level supervisor (monkey) asks the upper level manager (cat) to approve a decision (chestnuts). The manager (cat) is unaware of the peril and ends up approving a decision that was tainted by discrimination.
Before Staub, employers successfully argued that they could not be liable unless the actions of the discriminatory lower-level manager were the "sole influence" for the employer's adverse action. So, if the employer did even a minimal amount of review before approving the lower manager's recommendation, it could escape liability for the lower manager's unlawful motive. Staub killed this strategy.
Staub v. Proctor Hospital
Staub was an Army reservist, whom Proctor Hospital employed until it discharged him in 2004. Staub sued Proctor for violation of the Uniformed Services Employment and Reemployment Rights Act (– USERRA). Under — USERRA, an employer may be liable for unlawful discrimination if "the person's [military] membership is a motivating factor in the employer's action."
Staub claimed two of his supervisors openly discriminated against him because of his military status and activities. He further alleged that their actions, including trumped up disciplinary warnings for violations of non-existing policies, influenced the ultimate decision to terminate his employment. Staub acknowledged that the person who made the termination decision, the Director of Human Resources, had no discriminatory animus. Rather, she was the unknowing "cat's paw" of the discriminatory supervisors. Nonetheless, Staub argued that his lower-level supervisors discriminatory actions were "a motivating factor" in his termination, because the Human Resources Director based her decision on the supervisors' recommendation.
Proctor Hospital argued the "sole influence" theory to defeat Staub's claims. According to Proctor, the Director of Human Resources performed her own "independent investigation" by reviewing Staub's personnel file to verify past performance issues.
The Supreme Court adopted a broad standard, applying cat's paw liability if: (1) a supervisor acts with discriminatory motive; (2) the discriminatory supervisor intends to cause the adverse action; and (3) the discriminatory act is a "proximate cause" of the adverse action.
Staub's Impact on Internal Investigations
The Court also rejected the argument that a decision maker's independent investigation could scrub the decision clean of any discriminatory motive. That may work sometimes, but not always. If a supervisor has a discriminatory motive, the investigation must reveal an independent basis to support the adverse action. Otherwise, there is a lingering link between the bias and the decision. So long as that link is present, there is potential liability for unlawful discrimination.
Recommendations by lower-level supervisors cannot be "rubber-stamped." Now, there are two potential levels of investigation: (1) investigating whether there is any evidence of discriminatory animus by the lower-level supervisor; and (2) if so, investigating whether there is an independent basis to support the recommended adverse action.
Investigations: Prevention and Protecting Against Cat's Paw Liability
Employers may conduct internal investigations after complaints of discrimination or retaliation arise. However, by the time an investigation is initiated, the negative action likely has already taken place. Accordingly, the potential for cat's paw liability should prompt employers to consider "pre-adverse action" investigations in appropriate cases.
Not every discharge or other adverse action warrants a pre-investigation. For example, a manager responsible for making a decision without the need for approval from superiors does not have to investigate his or her own motivations. This situation may occur in smaller workplaces. It may also occur when the manager making the decision is the supervisor of the employee to be disciplined or discharged.
In cases where decisions are based on subjective criteria, or in larger businesses, however, a fresh look at the circumstances may be warranted. Employers with policies and procedures in place for pre-action review should examine whether the review is sufficiently thorough and systematic to avoid later claims.
At minimum, employers should ensure that decisions are supported by facts that can be verified objectively. If a supervisor wishes to discharge someone for violating a policy, the person reviewing the situation should be satisfied that the facts establishing the violation are verifiable. It is also important to determine whether a policy is applied consistently or selectively.
The investigator/reviewer should assess whether there is a "history" between the employee and supervisor, and whether the employee has made complaints in the past or otherwise could be vulnerable to a decision motivated by an illegal reason.
Identification of corroborating information is another important component. If the lower-level supervisor is recommending termination for attendance issues, have other supervisors identified the same attendance issues with this employee? The more corroboration there is, the less likely it is that there is a discriminatory lower-level supervisor attempting to use the employer as a cat's paw.
Another issue worth examination is to anticipate whether an employee will offer an excuse for the conduct underlying the negative action. It is worth determining if the decision maker is "pouncing" on an error that is attributable to something beyond the employee's control. Although employment is often "at will," the issue here is ensuring that a decision is motivated by lawful considerations.
As with most things employment law, documentation is very important. Managers and supervisors should be required to produce documentation to a reviewer or investigator that establishes the justification for proposed action, particularly if a supervisor takes the position that the employee "knew" of his or her performance deficiency, or that prior counseling had been given.
Other Tools to Help Employer's Avoid Becoming a Cat's Paw
Preventing "cat's paw" liability is consistent with good human resources practices generally. For example, employers should clearly communicate job expectations to employees so they understand what is expected. When an employee is not surprised by adverse action, the chance of a discrimination claim is reduced.
A proper open-door and complaint procedure is also important. When an employee is disciplined and does not seek a review or complain of unfair or discriminatory treatment, that helps the supervisor justify discharge or more severe discipline based on similar reasons.
Proper training also plays a role. Managers and supervisors should be trained how to communicate disciplinary action and job expectations. They also must be alerted to the company's efforts to prevent liability through a proper review procedure discussed above. Supervisors need to understand that their proposed negative actions will be subjected to scrutiny and analysis, which will encourage them to put more thought into their decisions.
The workplaces may seem to require quick decisions and operates at an increasingly faster pace. However, sound human resources policies permit management to "put on the brakes" to review and investigate before taking action that can result in expensive and time consuming employment claims.


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Members of the 6888th Central Postal Directory Battalion take part in a parade ceremony in honor of Joan d'Arc at the marketplace where she was burned at the stake (Rouen, France).
May 27, 1945
The 6888th Postal Battalion was an all female, all black unit responsible for sorting every piece of mail sent to US troops in the European theater. Letters from home were vital to maintaining morale, yet when the 6888th first arrived in Europe, letters were stacked to the ceiling of their temporary post office. Some letters had been in storage for as long as two years. Sorting the 90 billion pieces of mail sent to American troops in Europe required the women to keep track of the location of every US solider in Europe, including all 7,500 Robert Smiths. Some mail was merely addressed to "Junior" or "Buster." Yet thanks to their round the clock sorting, 65,000 letters went out three times a day to soldiers throughout Europe.
The women served in Birmingham (UK), Rouen (France), and Paris before being sent home at the end of the war. Like many female units, their work was not honored with any fanfare at the time. In 2009 the 1,000 women who served in the 6888th Postal Battalion were finally honored by the US Army at the Women's Memorial at Arlington National Cemetery.


text:
News in 2011
Inaugural Interdisciplinary Science Research Lectures: A smart wound dressing concept for detecting and treating infection in paediatric burn wounds
One of the missions of the IScience programme is to demonstrate the symbiosis of teaching and research. The Interdisciplinary Science Guest Research Lecture series aims provide lectures accessible to undergraduates and non-experts to raise awareness of current interdisciplinary research topics.
On 24th November 2011 our first speaker Dr Toby Jenkins, Head of Biophysical Chemistry Research at the University of Bath, discussed the science behind the creation of a smart wound dressing for detecting and treating infection.On 24th November 2011 our first speaker Dr Toby Jenkins, Head of Biophysical Chemistry Research at the University of Bath, discussed the science behind the creation of a smart wound dressing for detecting and treating infection.
There is frequent reference to 'nanotechnology' in the media, and many people, including Prince Charles, have an opinion on its merits – or otherwise. However, few people seem to know exactly what nanotechnology is – including many scientists. Still fewer have heard of 'nano-biotechnology': the applications of nanotechnology to biological systems.
Toby discussed one potential clinical application of this technology. The problem of infection, especially with the evolution of drug-resistant bacteria, such as MRSA, is well known but it is less known that infection is a cause of death in half of all people who die from thermal burns. The focus of the technology Toby and his team are developing is to treat burns in young children. This is part of a research project currently taking place across five European countries, applying nano-biotechnology to the fabrication of an advanced wound dressing which will monitor whether a wound or burn is infected by bacteria. If the wound becomes infected, the dressing will automatically release an antimicrobial agent and, if this fails to stop the infection, then changes colour to alert the patient or clinicians.
Collaboration to create new Sustainable Development module
A collaboration between the Centre for Interdisciplinary Science and the School of Biological Sciences has received funding from the HEA Bioscience Centre to create a new module on sustainable development. The Departmental Teaching Enhancement Scheme will provide funding to the develop sustainability literacy teaching for students in Biological sciences and in the College of Science and Engineering. This new module will build on the existing option for Interdisciplinary Science students by broadening the scope to include sociological, ethical and economic issues beyond the usual conservation biology option.
Science and Sustainability: Improving Livelihoods in Kenya
Students from the University of Leicester have left a lasting impression on local community groups in Lake Naivasha, Kenya, after visiting in April this year. They visited Naivasha as part of the Sustainable Livelihoods field course, which is run each year by the Centre for Interdisciplinary Science. The course allows students to apply skills learnt during their degree to tackling real world issues of sustainability. This year's student projects – 'Reduction of fluoride in drinking water' and 'Briquette making' - were particularly successful in raising awareness of key issues and transferring knowledge to local communities.
Although fluoride is added to drinking water in some areas of the UK, very high levels of fluoride can have a negative effect on human health. Students Amy Cook and Ashleigh Glossop found that drinking water from bore holes around Lake Naivasha had fluoride concentrations well above WHO guidelines for safe levels. Some people in the area had already taken steps to reduce fluoride in their water; however Ashleigh and Amy found that many people were unaware of the health risks of fluoride. They tested a simple method of reducing fluoride concentration in drinking water, using carbonised animal bones, and found it to be successful.
I-science students Alicia Peel and Zoe Bailey worked on a project researching and creating different "Briquettes" – a fuel source made from compressed waste material - with the intention of introducing them to local communities as an alternative to charcoal.
Zoe said, "We looked at how these Briquettes could be advantageous to local communities and how different characteristics of the Briquettes (e.g. ratios, components or preparation method) affected how effective they were a fuel source. We also investigated how charring [carbonising] the Briquettes or the components of the Briquettes affected their efficiency, as well as looking at a couple of possible methods of charring."
Zoe and Alicia found that, overall, charred Briquettes worked best (they burned hotter and gave out less smoke); however, non charred Briquettes still worked well and are simpler to produce. Briquettes have a number of benefits for local communities. They are made from waste material and therefore provide a low cost alternative to charcoal, they can also provide a sustainable livelihood for people making and selling the Briquettes. If Briquettes become widely adopted in the area they should help to reduce the environmental damage caused by the production and burning of charcoal.
Students worked with a number of local community groups including the Lake Naivasha Disabled Environmental Group (LNDEG). These community groups have now implemented some of the suggestions put forward by the students and they have found the information very useful. Thadius Mogendi, Chairman of the LNDEG, has kept in touch with the students by email to keep them up to date with the progress they have made since April.
Ed Morrison, a PhD student working on wetland restoration in Naivasha, worked with the students. He said, "The briquettes have helped disadvantaged communities, with no access to electricity, reduce their dependence on environmentally-destructive charcoal production. The students supplied the materials and training necessary for the LNDEG to produce biomass briquettes from locally-available and otherwise discarded waste materials. They are now busy selling this alternative fuel in the settlement, at KSh 3/briquette [2p] and helping to spread knowledge about re-use of wastes towards affordable and environmentally-positive fuel production for the rural poor, reducing local rates of deforestation in the process."
As well as helping local communities in Kenya, the students who take part in the field course also get a lot out of the experience. Zoe Baily said, "I really enjoyed the Kenya field course. Being in Kenya was a really great experience, I loved getting to meet the local people and learning what life was like for them. It was amazing to be able to experience an environment so beautiful and different from what I am used too."
Zoe went on the say, "I think the best part about the field course was that I got to work on my own project that I knew could actually be of real benefit to the local communities. I was especially pleased when I recently received an email update from the Lake Naivasha Disabled Environmental Group informing us that, after the presentation Alicia and I gave, they are now producing and selling Briquettes."
The Sustainable Livelihoods course is run by Emma Tebbs, Graduate Teaching Assistant for the I-Science course, and Dr David Harper, originator of the module, who is a Senior Lecturer in Ecology & Conservation Biology in the Biology Department. David also teaches ecology on the I-Science degree by running the 'Biosphere' module and sustainability by contributing to 'Sustainable Futures'. He has conducted scientific research in Kenya & Tanzania for over 25 years, focussing upon the sustainability of water resources.
The field course will take place again in 2012 during the Easter holidays, when another group of students will travel to Kenya to work on a new set of projects. The course is open to anyone at the university. Anyone interested in taking part can find out more by contacting Emma Tebbs – _EMAIL_.


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கருத்தெழுதிய அனைவருக்கும் மிக்க நன்றி...
இந்திய நடுவண் அரசின் மத்திய நீர்வள அமைச்சு(Ministry of Water Resources), முல்லைப் பெரியாரின் பிரச்சனையை பற்றிய புள்ளி விவரணையை இணையத்தில் வெளியிட்டுள்ளது... அதனை இங்கே பார்வைக்கு இணைக்கிறேன்..
Mullai Periyar Dam issue
On 29-10-1886 a lease indenture for 999 years was made between Maharaja of Travancore
and Secretary of State for India
for Periyar irrigation works by another agreement in 1970, Tamil Nadu was permitted to generate power also.
2. The Mullaperiyar Dam was constructed during _PHONE_ across Periyar River in the then Travancore state (now Kerala) territory after said indenture. The Periyar Dam with full reservoir level of 152 ft. provides for diversion of water from the reservoir through a tunnel to Vaigai basin in Tamil Nadu for irrigation benefits in 68558 ha.
3 In 1979, reports appeared in Kerala Press about the safety of Mulla Periyar Dam. On 25th
November, 1979 Chairman, CWC held discussions at Thirvananthapuram regarding strengthening Periyar dam with officers of Irrigation and Electricity, Deptt. of Kerala and PWD of Tamil Nadu. In the meeting, emergency measures to be completed before next monsoon (1980), medium term measures and long-term measures for strengthening of Periyar Dam were decided. One of the emergency measures was to keep the shutters of spillway raised fully to lower the reservoir level to 136 ft.
4. A second meeting under the Chairmanship of Chairman, CWC was held on 29th
April 1980 at New Delhi and it was opined that after the completion of emergency and medium term measures in the form of cable anchoring,
the water level in the reservoir can be restored up to 145 ft.
As per the Memorandum on the Rehabilitation of Mulla Periyar Dam prepared by CWC and forwarded to Tamil Nadu on 25th
March, 1986, emergency measures were implemented.
In the aforesaid Memo, CWC gave its recommendation about peak flood and size of additional vents to be added in the spillway for implementing remaining emergency measure of providing additional spilling capacity. It also gave its recommendation about the design details of concrete backing on the downstream face of the dam.
Besides this, CWC suggested The Government of Tamil Nadu to examine the possibility of raising the top of RCC parapet by another two feet apart from few other suggestions.It was opined in the forwarding note that after completion of the proposed strengthening measures, provision of other additional vents and implementation of other suggestions, Periyar dam would be competent to hold water upto FRL of 152 ft.
6. The matter became subjudice
with several petitions in the Kerala and Tamil Nadu High Courts. All these cases were transferred to the Supreme Court which heard the matter and desired in its order dated 28.4.2000 that Honorable Minister (WR) may convene a meeting of the Chief Ministers of both the states of Kerala and Tamil Nadu to amicably resolve the issue..
7. Honorable Minister (WR) convened the Inter-State meeting on 19.5.2000 and as decided in the meeting, an Expert Committee under Member (D&R), CWC with representatives from both States was constituted in June 2000 to study the safety of the dam with respect to strengthening of dam carried out by The Government of Tamil Nadu on the advice of Central Water Commission and advise regarding raising of water level in the reservoir beyond 136 ft as a result of strengthening of dam.
8. The Committee in its report of March, 2001 opined that with the strengthening measures implemented, the water level can be raised from 136 ft. to 142 ft. without endangering safety of the dam. Further raising of water level to 152 ft. will be considered after balance strengthening measures are implemented.
9. In the case of Transfer Petition (Civil) No. 779-783/1998 Dr. Subramanian Swamy Vs Tamil Nadu, the Report of the Expert Committee was filed in the Honorable Supreme Court on 31.8.2001 and also sent to the State Governments of Kerala and Tamil Nadu.
10 In writ Petition ( C) No. 386 of 2001 (Mulla Periyar Environmental Protection Forum Vs Union of India and Ors) the Supreme Court in its Judgement dated 27.2.2006, permitted the Government of Tamil Nadu to raise the water level of Mulla Periyar dam from 136 ft. to 142 ft. and take up the remaining strengthening measures.
11. Consequent to the aforesaid orders of the Supreme Court of India, the Kerala Government passed the Kerala Irrigation and Water Conservation (Amendment) Act 2006 which received the assent of the Governor on 18th March 2006 which prohibited the raising of water level beyond 136 ft. in the Mulla Periyar Dam as Mullaperiyar Dam was placed under the Schedule of "Endangered Dams".
12. The Government of Tamil Nadu filed a suit No. 3 of 2006 - State of Tamil Nadu v/s State of Kerala and Union of India in the Honorable Supreme Court on 31.3.2006 praying for -
- Declaration of Kerala Irrigation and Water Conservation (Amendment) Act 2006 passed by Kerala Legislature as unconstitutional in its application to and effect on Mulla Periyar Dam.
- Pass a decree of permanent injunction restraining Kerala from application and enforcing impunged legislation enforcing with or obstructing Tamil Nadu from increasing the water level to 142 feet and from carrying out the repair works as per judgment of Supreme Court dated 27th February 2006.
13. A Review Petition filed by the State of Kerala on 3.4.2006 was dismissed
by the Supreme Court on 27.7.2006.
14. In the matter referred to in para 13 above, the Honorable Supreme Court has passed an order on 25.9.2006 stating the two State Governments independently or with the intervention of the Union of India may try to sort out the dispute, if possible.
15. The Honorable Union Minister (WR) convened an inter-State meeting of the Chief Ministers of States of Tamil Nadu & Kerala on Mulla periyar dam issue on 29.11.2006 at New Delhi. Honorable Union Minister (WR) further discussed matter with the Minister (WR/PW) from the States of Tamil Nadu & Kerala on18.12.2006. The States of Tamil Nadu and Kerala reiterated their respective stand
in the meetings and no consensus could be reached regarding a solution acceptable to both States. The matter is now subjudice.
16. Subsequently, Honorable Chief Minister of Tamil Nadu met Honorable Prime Minister on 18.12.2007 and Honorable Prime Minister suggested him to have a meeting with Honorable Chief Minister of Kerala on Mulla Periyar issue. Honorable Chief Minister of Tamil Nadu met Honorable Chief Minister of Kerala on 19.12.2007 in presence of Honorable Union Minister of Water Resources. Further a letter dated 20.12.2007 was received from the Honorable Chief Minister of Tamil Nadu mentioning that in the above meeting, Honorable Chief Minister of Tamil Nadu suggested to oversee the seepage measurement of the dam by Engineers not belonging to either of the two States through CWC and Honorable Chief Minister of Kerala agreed to consider them.
17. Later, the Govt. of Tamil Nadu forwarded a letter dt 22/1/08 of Honorable Chief Minister of Kerala addressed to Honorable Chief Minister of Tamil Nadu wherein it is mentioned that in the meeting dt 19/12/2007 he suggested a joint mechanism to monitor the seepage. The Govt. of Tamil Nadu also enclosed a letter dated 4/2/2008 from Honorable Chief Minister of Tamil Nadu addressed to Honorable Chief Minister of Kerala wherein it is mentioned that joint monitoring was not discussed in the meeting.
18. CWC was requested to suggest a suitable mechanism for monitoring the seepage and possible structure of the Committee to monitor it. They suggested a ninemember Committee headed by a Chief Engineer, Central Water Commission having representatives from both States for Monitoring the seepage of Mulla Periyar Dam. The composition of the Committee along with terms of reference was sent to Chief Secretary, Government of Tamil Nadu and Kerala vide letter dated 28.4.2008 for


as if
Definition of as if
 1. 1 : as it would be if It was as if he had lost his last friend.
 2. 2 : as one would do if He ran as if ghosts were chasing him.
 3. 3 : that It seemed as if the day would never end.
 4. 4 —used to say that something is not true, not possible, will not happen, etc. "I am sure I am very affectionate," said Dora; "you oughtn't to be cruel to me, Doady!" "Cruel, my precious love! As if I would—or could—be cruel to you, for the world!" — Charles Dickens ; sometimes used informally as an interjection to say that something suggested or claimed is impossible, incorrect, or ridiculously unlikely to be true A simple collection of songs? As if. How about a conceptual ode to London's millennia-old history? — Craig McLean Big budgets? High-priced actresses? As if! The film cost a modest $13 million, a figure achieved by not casting stars, but rather stars-in-the-making … — Nicholas Fonseca
Examples of as if in a sentence
 1.
13th Century
First Known Use of as if
13th century
AS IF Defined for Kids
as if
Definition of as if for Students
 1. 1 : the way it would be if It's as if we'd never left.
 2. 2 : as someone would do if They acted as if they knew me.
 3. 3 : 2that 1 It seemed as if the day would never end.
Learn More about as if
Seen and Heard
What made you want to look up as if? Please tell us where you read or heard it (including the quote, if possible).
a side road used to avoid a toll
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ML Career Presentation (Individual Performance Event) ARIZONA ONLY
This event allows members to combine career research with verbal presentation skills. One of the goals of FBLA is to prepare members for the workforce. This event begins that process through career exploration.
Each Middle Level chapter may enter members who are on record in the FBLA-PBL Online Membership System as having paid dues by the officially published deadline for the current school year.
Spring Competition Procedure
Members are to identify their dream career and conduct research for your presentation. The presentation should include the following information (but can include more):
1) What type of education is needed to enter into this career?
2) Is this career in high demand?
3) What part of the country would have the most of these types of careers?
4) What is the average starting pay for this career?
Based on their research members will create a "Dream Career" board on a tri fold presentation board. The board can include computer generated items, hand written items, etc. The more creative the better. We will NOT provide power however. Members will have up to 5 minutes to set up their presentation board and materials. The presentation will be 2-5 minutes long and will answer the four questions listed above plus provide any additional information that is relevant to the career.
Chapters may enter an unlimited amount of individuals at competition. The top three (3) winners are recognized.
CLICK HERE for the the rating sheet
Missey Goodman, State Adviser
Office: _PHONE_
Fax: _PHONE_
 - YouTube


Main Content
Duration in days
D = days(X) returns an array of days equivalent to the values in X.
 - If X is a numeric array, then D is a duration array in units of fixed-length days. A fixed-length day is equal to 24 hours.
 - If X is a duration array, then D is a double array with each element equal to the number of fixed-length (24-hour) days in the corresponding element of X.
The days function converts between duration and double values. To display a duration in units of days, set its Format property to 'd'.
collapse all
X = magic(2);
D = days(X)
D = 2x2 duration
 1 day 3 days
 4 days 2 days
Add each number of fixed-length days to the current date and time.
t = datetime('now') + D
t = 2x2 datetime
 24-Feb-2021 14:52:50 26-Feb-2021 14:52:50
 27-Feb-2021 14:52:50 25-Feb-2021 14:52:50
Create a duration array.
X = hours(23:20:95) + minutes(45)
X = 1x4 duration
 23.75 hr 43.75 hr 63.75 hr 83.75 hr
Convert each duration in X to a number of days.
D = days(X)
D = 1×4
 0.9896 1.8229 2.6562 3.4896
Input Arguments
collapse all
Input array, specified as a numeric array, duration array, or logical array.
 - days creates fixed-length (24 hour) days. To create days that account for Daylight Saving Time shifts when used in calendar calculations, use the caldays function.
Extended Capabilities
See Also
Introduced in R2014b


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Multilevel factor analysis models are widely used in the social sciences to account for heterogeneity in mean structures. In this paper we extend previous work on multilevel models to account for general forms of heterogeneity in confirmatory factor analysis models. We specify various models of mean and covariance heterogeneity in confirmatory factor analysis and develop Markov Chain Monte Carlo (MCMC) procedures to perform Bayesian inference, model checking, and model comparison.
We test our methodology using synthetic data and data from a consumption emotion study. The results from synthetic data show that our Bayesian model perform well in recovering the true parameters and selecting the appropriate model. More importantly, the results clearly illustrate the consequences of ignoring heterogeneity. Specifically, we find that ignoring heterogeneity can lead to sign reversals of the factor covariances, inflation of factor variances and underappreciation of uncertainty in parameter estimates. The results from the emotion study show that subjects vary both in means and covariances. Thus traditional psychometric methods cannot fully capture the heterogeneity in our data.
Ansari, Asim, Kamel Jedidi, and Laurette Dube. "Heterogeneous Factor Analysis Models: A Bayesian Approach." Psychometrika 67, no. 1 (March 2002): 49-78.
Each author name for a Columbia Business School faculty member is linked to a faculty research page, which lists additional publications by that faculty member.
Each topic is linked to an index of publications on that topic.


May 23 2011
Category: Medical Supplies
Power WheelchairsThere are many differences between a power chair and a motorized scooter. The major differences involve indoor vs. outdoor use and the degree of body strength, posture integrity, and walking ability experienced by the user. Price should also be included in the comparison since most power wheelchairs are more expensive than scooters. Power wheelchairs are also more likely to be covered by Medicare and scooters are usually not.
A power wheelchair or electric wheelchair is best used in the home for routine activities of daily living and for getting around from room to room. A power chair is ideal for someone who has very limited mobility and, without the power wheelchair, would not be able to move around without someone helping them most of the time.
A mobility scooter can be used in the home, but it is better for outdoor use, since scooters are usually too large and difficult to maneuver through narrow rooms and small areas. Also, the person who uses a power scooter must be able to support their own body for a long time and be able to steer a handlebar. Scooters are usually for people who have just a slight problem with walking for long periods of time.
Tags:,,,
One Response to "What is the difference between a power wheelchair and a power scooter?"
 1. Angela H. says:
 Nice definition, but I have one caveat.
 A Medicare beneficiary may be eligible to receive a portion of their money back from Medicare when they purchase a scooter. But, in order to qualify, they must have Medicare Part B coverage and they must meet certain medical coverage criteria as determined by their doctor. So, sometimes, a power scooter will be covered by Medicare. It all depends on the individual's needs, the doctor's diagnosis, and Medicare's specific guidelines.
Challenge this Answer and/or Discuss


text:
Create an aquarium environment that simulates the natural habitat of your aquatic inhabitants with Hagen Air Curtain Air Diffuser from Pet Store
. Covering a large surface area, these air tubes are porous, enabling it to release powerful flow of air. It aerates your tank and at the same time moves the water similar to the natural water current in both marine and freshwater environments. Amazingly, even with its powerful aeration and water agitation, the diffuser does not move out of its place. It is securely held by ceramic weights so that it can perform its functions without being carried by its own thrusts.
This diffuser measures fifteen inches in length. It is flexible and can be converted to various shapes to develop lovely display of air curtains and bubbles. It also does not require too much pressure to be able to release air and move water. It does not use oxygen that your fish and other aquatic life need.
The Hagen Air Curtain Air Diffuser is convenient to use and easy to clean. It comes with a cleaning ring that glides along the diffuser's tube to avoid pollutants and harmful substance from clinging and clogging the tubes. This diffuser is ideal for all sizes of tanks and can be used for both freshwater and saltwater
- The Power Agitator
- Flexible, porous air tubes with large surface area
- Provide powerful aeration and water agitation
- Complete with ceramic weights to hold in place
- Can be formed into many shapes to produce beautiful bubble displays and air curtains
- Requires very little pressure
- Does not consume oxygen vital to fish
- Include cleaning ring that slides along the tube to prevent clogging
- Safe for fresh or salt water


How to Brew Smoked Beer: Rauchbiers, Smoked Stouts, and More
Smoked beer can be polarizing. While some people love it, others can't stand it. Is it an acquired taste? Or are there not enough great quality smoked beers available on the market? We're here to shed some light on this often misunderstood area of brewing.
With many breweries reviving this historic style, smoked beer is becoming increasingly popular. Still though, for the best and freshest versions, you'll need to brew it yourself!
How To Brew A Great Smoked Beer
Fans of Scotch, Southern barbecue, smoky bacon, and smoked salmon should all try brewing a smoked beer. And even if you don't love other smoked food and drinks, smoked beer might bring a new and interesting aspect to your brewing repertoire.
What is a Smoked Beer?
Smoked beers refer to all beers with a smoky flavor. No… the beer isn't put in a smoker like making smoked ribs!
Instead, smoked beer is made with malt that has been dried in wood-fired kilns. This malt absorbs the flavor of the burning wood smoke, which is transferred into beer during the mashing process.
Smoked beer comes in a wide range of flavors, styles, strengths, and colors. The one common thread is the use of smoked malt, in varying percentages.
What is Smoked Malt?
Smoked malt is the key to smoked beer. Interestingly, all beer was once brewed with smoked malt. That's because malted barley was exclusively kilned over wood-fired ovens, where the smoke passed through the malt. This imparted that unmistakable smoky taste in all brewer's malt as it dried.
During the industrial revolution, through the 17th century, coal fired kilns began to replace most wood-fired ones. Smoke from the burning coal was diverted to chimneys, and the residual heat produced by the coal was what was used for drying the malt.
Because of this, smoked flavor was eliminated from nearly all malt. Brewers and consumers alike began enjoying the more neutral flavored malts. The shift allowed brewers to have more flexibility in highlighting hop and yeast expression.
Wood smoked malt was relegated to traditional breweries and specialty beers. Today, several maltsters make specialty smoked malt, and some breweries even produce their own. The largest smoked malt producing maltster is Weyermann, in Bamberg, Germany.
Types of Smoked Malt
Smoked malt is usually malted barley, but smoked wheat malt is also fairly common. Malt can be smoked with any type of wood, but the most commonly available are:
 - Beechwood: Traditional and most common type of smoked malt, often sold as Rauch Malt or Rauchmalz. Very smoky but pleasantly balanced.
 - Oak: Rounded and subtle smoke flavor. Often used for smoked wheat production.
 - Cherrywood: Commonly found in the U.S. Balanced smokiness much like beechwood smoked malt.
 - Peat: High smokiness and an almost acrid flavor. This is what Single Malt whisky is made from for that intensely smoked profile.
Smoked Beer Styles
Smoked Marzen
General in name, Rauchbier directly translates to "smoke beer" from German. In Germany, the term Rauchbier refers to all types of beers made with smoked malt. Confusing perhaps, outside of Germany, Rauchbier generally refers to a specific style of beer: smoked marzen.
Smoked marzen is dark, malty, and very smoky but backed by delicious malt sweetness. Hop bitterness is subdued but present, adding to drinkability. It's a marzen, a classic German lager, but made with nearly 100% smoked malt.
The most quintessential smoked beer, Aecht Schlenkerla Rauchbier Märzen, is world-class and a must-drink for any fan of smoked beer.
Smoked Pale Lager
Less common, but equally delicious, are smoked pale lagers, like smoked helles and smoked pilsner. With all of the thirst-quenching and crisp qualities of the base style, the added layer of smoke creates a delicious new dimension.
Brewed with 40 to 60% smoked malt, smoked pale lagers come across exceptionally smoky due to the subtle base malt and hop flavors. Served cold and highly carbonated, there may be no better pairing for barbecued foods like sausages and pulled-pork.
Grodziskie is a historic smoked beer from Poland. Dating back to the 14th or 15th century, the style is a light and refreshing ale brewed with oak-smoked wheat malt. It's very effervescent and bright, with a rounded body and soft mouthfeel from the wheat malt.
At around 3 to 4% ABV, Grozsikie is similar to Belgian grisette, but brewed with 100% oak-smoked wheat malt and fermented with a clean German ale yeast.
Smoked sour ale – certainly not a beer for everyone. You might be surprised by the complex mix of flavors that Lichtenhainer puts forth. The style originates in Thuringia, Germany and is usually brewed with equal parts pilsner malt, wheat malt and smoked malt.
It's light in body, low in alcohol, pale and refreshing, very much like Berliner Weisse, but not quite as tart. The subtle layer of smoke adds to its drinkability and complexity, creating a very unique and quaffable beer.
Smoked Porter and Smoked Stout
Porters and stouts are common candidates to be smokified. Whether you're brewing a session strength porter or a sticky imperial stout, a bit of smoked malt can complement the roasted and chocolatey malt.
When brewing smoked stouts and porters, be sure to retain some residual sweetness. Too dry, black smoked beers can come across burnt tasting. Using an English yeast, like Wyeast 1318 London Ale III, or incorporating some caramel malts can help soften the mouthfeel.
What makes a good Smoked Beer?
Smoked beer can vary widely in style and level of smokiness. Depending on the brewer's vision, beers can range from very subtly smoked to face-in-a-campfire levels. There are no minimum or maximum thresholds for smokiness.
Generally, smoked beer should be balanced. If it's very smoky, malt sweetness and balanced bitterness should complement those intense flavors. For lightly smoked beers, like smoked pilsner or helles, crisp malt backbone and herbal hoppiness is desirable.
For those unaccustomed to smoked beer, it does take some getting used to. Many people directly associate smoked flavors with food – like bacon or smoked ham – which can be a bit mind-bending in the context of beer.
Per Schlenkerla, the masters of smoked beer:
How to brew Smoked Beer
Brewing smoked beer takes experimentation and an ambitious brewing spirit. Using smoked malt, you need to be willing to accept that the beer might come out a little "too much" or "not enough". The more you brew with smoked malt, the more consistent you'll be able to design recipes.
Generally, smoked beers are not overly hoppy. Assertive hop character can clash with smoked flavor, or the smokiness can overwhelm hoppiness. That said, a smoked NEIPA may be possible with the right mix of ingredients – I've certainly been considering experimenting.
Recipe design
Smoked malt can replace a certain percentage of the base malt from most beer recipes. If you have a favorite helles or pilsner recipe, swap out 40 to 50% of the pilsner malt with smoked malt.
Here's a handy guide that can help with smoked beer recipe decisions:
Style Average Smokiness Smoked Malt % Other Malts Yeast
Smoked Marzen (Rauchbier) ⬤⬤⬤⬤⬤⬤⬤⬤◯◯ 90 – 100% CaraMunich (2%), roasted barley (2%) Lager
Smoked Helles ⬤⬤⬤⬤⬤⬤◯◯◯◯ 20 – 50% Pilsner Lager
Smoked Pilsner ⬤⬤⬤⬤◯◯◯◯◯◯ 10 – 30% Pilsner Lager
Grodziskie ⬤⬤⬤⬤⬤⬤⬤⬤⬤◯ 100% oak-smoked wheat German Ale
Smoked Stout and Porter ⬤⬤⬤⬤⬤◯◯◯◯◯ 15 – 40% Pale malt, roasted barley, chocolate malt, caramel malt Ale or Lager
Lichtenhainer ⬤⬤⬤◯◯◯◯◯◯◯ ~33% Wheat (33%), Pilsner (33%) Lactobacillus and Ale
Recipe: Smoked Pilsner
This is a simple Smoked Pilsner recipe that's a great introduction to the world of smoked brewing. A touch of wheat helps round out the mouthfeel, and a heavy hand of smoked malt comes across smoky but balanced.
It's extremely refreshing and drinkable like a Pilsner, but with a layer of unique smoked complexity.
Final Volume Original Gravity Final Gravity ABV IBU SRM
5 Gallons 1.048 1.008 5.3


Title: The dynamics and control of in-situ combustion.
Author: Young, Tobias J.
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 1997
Availability of Full Text:
Access through EThOS:
Improved oil recovery (lOR) techniques target the 60% of oil left behind by primary and secondary methods (those that utilise the natural energy of an oil reservoir). Air injection in situ combustion (lSC) is a thermal lOR technique used in general to increase the temperature in a reservoir and in turn reduce the viscosity of the oil. This increases the mobility of the oil and can lead to significant improvement in recovery factors. The process is complex and much work is needed to improve modeling capabilities essential for reservoir management. To investigate high pressure air injection a combustion tube facility has been commissioned and four in situ combustion tube tests completed. This involved the development of data acquisition and control software (lsc View) to fully automate the air injection facility. The ISC tests were carried out with a West Shetland Clair crude oil of 19.7°API and air injection fluxes between 12 and 70m3/m2hr and pressures between 50 and 100 bar. Post-mortem analysis of the burned cores showed 100% oil displacement in areas of core swept by the combustion front. In these areas the amount fuel burned varied between 4.6 and 15.3 %OOIP (original oil in place). The combustion front temperatures varied between 450°C and 730°C. It was found that combustion front temperature increased with air injection flux. The combustion front velocity varied between 10.4 and 22.2cmlhr. The combustion front velocity was observed to increase with pressure thus the combustion front velocity and hence propagation of the combustion front was shown to be reaction rate dependent. History matching of the ISC tests was completed using the STARS simulator (Computer Modeling Group) a fully implicit non isothermal reservoir simulator. The simulations showed that when the grid size approached that of the actual reaction zone then the kinetics at different pressures did not change. Therefore, at this grid scale, the kinetic parameters used for a pseudo component representation of the oil can be applied as if it were a pure component, independent of pressure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: DOI: Not available
Keywords: Oil recovery


Tahoe Tessie
From Wikipedia, the free encyclopedia
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Tahoe Tessie is a cryptozoological creature which supposedly resides in North America's largest alpine lake, Lake Tahoe, located in Nevada and California. Tales of the lake-dwelling creature can be traced to stories told by members of the Washoe and Paiute tribes in the mid-19th century, stating that the creature resides in an underwater tunnel beneath Cave Rock, and sightings have continued into modern day.
Sightings describe Tessie as being between 10 and 80 feet long, having a large, serpentine body "as wide across as a barrel," and coloration ranging from jet black to turquoise. Its skin is usually described as smooth, despite having reptilian features.
In the 1950s, two off-duty police officers out on the lake reported seeing a large, black hump rise from the water, and keep speed with the boat, going over 60 mph (97 km/h).
According to an anonymous witness on Weird California.com, "Myself, along with 3 others watched a large serpent-like creature feeding/hunting in a school of large trout. It was in the middle of winter of 1979 off the dock at Homewood. It was about as big around as a telephone pole and maybe 30'-60' in length from what we could see of it. It didn't swim like a snake (side to side). It was diving up and splashing down with its head/neck? into the school of fish, which were leaping out of the water ahead of it. We were speechless for several minutes afterwards."
In the 1980s, two fishermen reported seeing a 15-foot-long (4.6 m) serpent pass underneath the surface of the water, near Cave Rock.
Several weeks after, two divers reported finding an underwater cave, and a creature shot out, leaving the silt stirred. Where the creature had been, there were two large fin-prints.
Sometime in the late 1990s, a kayaking instructor reported seeing a glance of what looked like a green two-person kayak flip over and immediately sink. When he approached the area in a speedboat, there were no traces of the kayak, and his students did not report flipping over at any time.
In 2004, an off-duty bartender on the Tahoe Queen took a picture of a black hump in the water, which he claims is the top of the creature's head.
In 2006 a family vacationing near Tahoe sited a large, black, scale lacking creature appearing similar to a sturgeon with an upturned white nose. However the creature moved up-and-down like a mammal instead of side-to-side like a reptile.
There has been rumored Tessie footage, which is reportedly being analyzed before being released to the public.
There have been many theories surrounding Tahoe Tessie, the most popular being that it is either a Plesiosaur, Pliosaur, Ichthyosaur or a Mosasaur, due to fossils of the creatures being found in the Surrounding Nevada Desert, and Sierra Nevada mountains. These theories are quickly dismissed by many Tessie experts, stating that the lake was formed in the last Ice Age, long after the creatures went extinct. Other theories say that it may be anything from a population of Sturgeon, to a new species of Freshwater eel.
In the media[edit]
Tahoe Tessie is a popular logo for many Tahoe-based companies, with a cartoon version being in many children's picture books, and a popular character featured in local newspapers. There even used to be a local museum and hotline, but both recently closed.
Purported sightings continue in modern times.[1][2]
 1. ^ "Tahoe Tessie". americanmonsters.com. Retrieved 2009-05-24. [dead link]
 2. ^ Sheffield, Keith (2005-04-29). "Dark shapes in the lake: Tahoe Tessie legend remains alive for visitors". Tahoe Daily Tribune. Retrieved 2013-07-22.


text:
In Windows 10 build 18298, are a number of changes were made to the built-in console subsystem of the operating system. There is a new "terminal" tab in console option that allows adjusting several new options for the Command Prompt, PowerShell, and WSL. One of them is the ability to change the cursor shape.
Windows Console subsystem is utilized by certain built-in apps of Windows 10, including the Command Prompt, PowerShell, and WSL. In Windows 10 Build 18298, which represents the upcoming version 19H1, also known as version 1903, you will find a set of experimental options of the console.
These settings are "experimental", because in certain scenarios, it's possible that they might not behave like you would expect them to, may not make it into the next OS release, and may change completely in the final version of the OS.
One of the is the shape of the cursor. It will be set for the specific shortcut you used to open a console instance. E.g. if you have multiple command prompt shortcuts, you can set the desired cursor shape for each of them individually. This way, PowerShell, WSL, and the command prompt may have their own independent settings.
Console Cursor Shapes
At the moment of this writing, Windows supports the following cursor shapes for the console.
Legacy Style - this one is the classic console cursor.
Here is how to switch between them.
To change the cursor shape in the console in Windows 10,
- Open a new command prompt window, elevated command prompt, PowerShell, or WSL.
- Right-click on the title bar of its window and select Properties from the context menu.
- Switch to the Terminal tab.
- Under Cursor Shape, set the desired cursor shape.
You are done!
Tip: With Windows 10, Microsoft added an ability to have a semi-transparent console window for cmd.exe, and PowerShell. It's a lesser known feature that you can change the transparency level on the fly for the current window with hotkeys. See
Articles of interest:
- Pin Admin Command Prompt to Taskbar or Start in Windows 10
- Use Ctrl + Mouse Wheel To Zoom Windows 10 Console
- Download Official Windows Command Reference For Over 250 Console Commands
- Download Color Schemes for Command Prompt in Windows 10
-... and more!


Altai Balance Canada – Advanced Blood Balance Supplement Reviewed!
Jul 22, 2021
Altai Balance supplement is a progressive and pristine formulation that upholds optimal glucose levels in Canada. With an amazing amalgam of berries and other ingredients, Altai Balance can dependably regulate blood sugar levels and improve one's immunity.
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Each Altai Balance pill comprises a blend of 19 top-caliber, home-grown ingredients. It possesses the fundamental motivation behind detoxifying hazardous particulate matter. This particulate matter makes the body store more fat and diminishes insulin sensitivity. In this manner, it hinders the digestion of the blood glucose levels.
As indicated on the Altai Balance Official Website, it is the lone all-organic anti-aging blend that targets the root cause of unbalanced glucose. It benefits include:
Knowledgeable blood science,
Powerful digestion,
Ensured cells,
Superior degrees of energy and imperativeness,
A much more youthful looking self.
Altai Balance Canada Reviews – A Dietary Supplement that Upgrades Overall Wellbeing?
Type-2 diabetes is perhaps a crippling medical issue that influences a large number of men and women in Canada. Today, almost 10 percent of individuals are probably suffering from type-2 diabetes.
Overseeing high glucose has been a typical issue for the vast majority of people. Under normal circumstances, the pancreas delivers sufficient insulin to the body cells. But, few people devour more sugar and carbs than they ought to. This opens their pathways to the steady risk of obesity. When a person keeps on stacking up more weight, diabetes sets in. Overseeing type 2 diabetes requires the mediation of a specialist. He/she screens the glucose levels over time.
Altai Balance is an effective and natural supplement that attempts to maintain favorable glucose levels. This high level glucose support formula professes to wipe out the underlying driver of type-2 diabetes.
What Ingredients Constitute Altai Balance?
Altai Balance ingredients list contain a shifted blend of herbs and spices that can cut down glucose and eliminate harmful toxins from the blood.
Chromium: This ingredient is fit for making the cells more open to the activities of insulin hormone. Besides, it helps with adjusting glucose and controlling diabetes.
Biotin: Biotin helps to convert carbs, fats, and proteins into energy that the body needs.
Vitamin B: These micronutrients play a pivotal role in separating sugars and utilizing them for energy creation. This is a fundamental prerequisite for stable glucose upkeep.
Vitamin C: Being practically the same as glucose, these particles can vie for assimilation. If the blood glucose is high, Vitamin C can get spent. It is a viable antioxidant that guards against any harm that may emerge because of expanded glucose levels.
Vitamin E: It develops insulin affectability and highlights insulin resistance in overweight people. Diminished glucose fixations and fasting plasma insulin, joined with expanded HOMA, can offer subjects with developed insulin sensitivity.
Manganese: This micronutrient works with the proteins and regulates blood sugar levels.
Cinnamon: It brings down glucose levels by acting like insulin. In the end, it triggers a typical insulin reaction.
Magnesium: The body needs magnesium to synthesize insulin. Insulin stores magnesium in the cells. If the cells become insulin resistant, magnesium gets used up.
Alpha Lipoic Acid: This ingredient helps in dealing with extreme harm brought about by expanded sugar levels.
Licorice: This fixing upholds the adrenal organs, and further adds to glucose balance.
Fenugreek seed: Fenugreek helps in easing back the assimilation of sugar into the blood.
Zinc: It provides assistance during various parts of cell digestion, and illnesses identified with zinc lacks.
Bitter Melon: It is a powerful antioxidant that fixes blood chemistry and lowers blood glucose levels.
The other ingredients include Cayenne pepper, Cinnamon bark, Juniper berries, and White Mulberry extract.
Altai Balance Advantages – The safest method to regulate blood sugar?
Altai Balance pills assure steady and healthy glucose levels.
The supplement lowers fat mass and improves muscle mass.
It decreases uneasiness levels and expands energy levels.
The formula flushes out harmful fats from the circulatory system.
It accelerates energizing glucose digestion.
The benefits prompt a more satisfied life without stress over the long haul.
The capsules support a better immune system and assists you in your fight against infections, microscopic organisms, and illnesses.
Each tablet is produced using all-natural ingredients.
The supplement is made in an FDA affirmed office in the USA.
There are no side effects.
The formula is non-habit-forming and non-resilience framing.
How Does Altai Balance Supplement Work?
To help bring back the glucose to its ideal level, Altai Balance contains pure and powerful ingredients. These fixings possess an ability to control your glucose levels. As per the official site, Altai Balance formula resets your glucose levels. It delivers mystical outcomes with respect to your glucose and waistline.
Predictable utilization of the supplement helps support a sound healthy heart, mind, and joints. Besides, it helps your energy levels and works on wellbeing. The most awesome aspect of utilizing Altai Balance is that it works with your normal diet. When your glucose levels will be at their ideal level, you will achieve a lean and thin body that you've longed for.
Click Here To Check the Availability Of Altai Balance Supplements in Canada
To summarize, Altai Balance works by:
It detoxifies the circulatory system of harmful particulate matter.
The pills postpone the digestion of starches into glucose.
It provides you additional energy by burning fat and utilizing unused glucose.
It shields cells from future harm.
What is the ideal Altai Balance Dosage?
Altai Balance is suggested for individuals who are more than 18 years old. The creators recommend taking the supplement once daily on a consistent basis with food. It is strongly prescribed to counsel a medical services provider prior to taking a dietary supplement, particularly if you are a pregnant lady and nursing mom.
Altai Balance begins delivering recognizable outcomes within 3 weeks of use. But, the results may vary across people.
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Are there any serious Altai Balance Side Effects?
Altai Balance does not cause any side effects. If you take more than one pill daily, suppose two, you may face light indications of side effects like cerebral pains or queasiness. Therefore, we suggest that you take the supplement as per suggested measurement. Still, if you follow the suggested measurements and feel irregular indications, promptly quit utilizing it and counsel your doctor for legitimate advice.
Is Altai Balance A Scam?
No, it is not. By perusing this review I can comprehend that it is a real supplement. It can possibly regulate blood sugar levels and provide assistance in your fight against obesity.
Aside from that, the supplement delivers ensured results. If not, you are allowed to get a full refund of your cash. Also, that would be conceivable inside 60 days after you register your purchase.
Where to Buy Altai Balance at Best Price in Canada?
You can Buy Altai Balance at the Official Website, no where else. If you buy from another source, you are responsible for the associated risks such as opening yourself to ill-produced duplicates. The latest prices are as follows.
One Bottle (30 Day Supply) is valued at $49.
Three Bottles (90 Day Supply) is accessible for a discounted cost of $117.
Six Altai Balance Bottles (180 Day Supply) cost mere $204.
Moreover, the merchant expects their clients to avoid buying the supplement from an outside source like Amazon, eBay, or WalMart. Payments can easily be completed through PayPal, Mastercard, and Visa.
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TECNAR Laser UT Productslut icon
Non-Contact Ultrasonics From The Laboratory To The Plant Floor
 As someone working in nondestructive testing, you have often encountered situations where contact between the sensor and the inspected part is difficult or simply not possible. Laser-ultrasonics is a novel inspection technique that combines the precision of ultrasonic inspection to the non-contact nature of optical detection. The use of laser-ultrasonics has been demonstrated in a wide variety of applications ranging from inspection of aerospace composite materials, to coating analysis with laser generated surface waves, to in-plant wall thickness measurements of hot mechanical tubing.
 Until recently, access to commercial laser-ultrasonic equipment has been rather limited. Tecnar Automation Ltee (TECNAR) has taken the task to development and market laser-ultrasonic equipment for use in both laboratory and industrial environments. TECNAR has made recent advances to bring laser-ultrasonics out of the hands of laser experts and into to the hands of NDE operators.
 TECNAR has introduced the TWM, a compact fully integrated detection system that is easy to setup and to use. The TWM is the perfect tool to add a sensor to your testing equipment. Also, TECNAR has introduced the FPC, a robust detection system that has the fastest response time for laser-ultrasonic detection. The FPC is perfectly adapted for use on mobile target as well as for rapid scanning of stationary parts.
 TECNAR can also deliver complete laser-ultrasonic system for dedicated application. In particular, the LUT is a Laser-Ultrasonic Thickness gauge for on-line wall thickness and eccentricity measurement of hot seamless steel tube.
 Introduction to laser-ultrasonics
 Laser-ultrasonics is a combination of the precision of ultrasound measurements with the flexibility of optical systems. Ultrasonics is a well known non-destructive technique that can provide several parameters of interest for materials. The measurement of the time-of-flight of an ultrasonic wave within the bulk of a material can directly measure the thickness, provided that the velocity of sound in the material is known, or can determine the presence of defect within the bulk of the material. The method is used in several industries, such as for aircraft inspection or thickness gauging of metal, because it provides high accuracy measurements. Subtle changes in wall thickness are easily detected and quantified.
 Measurements of ultrasonic velocity, when the materials thickness is known, can also be used to determine internal temperature, phase changes (such as austenitic to ferritic transition), texture and porosity. Ultrasonic attenuation (i.e., the reduction in sound amplitude between successive ultrasonic pulse echoes) provides additional information on the materials internal structure, in particular, provides a direct method for grain size measurement in-situ of metallic samples.
 Laser-ultrasonics is a combination of two separate methods: laser generation of ultrasounds and laser detection of ultrasounds. Laser generation of ultrasounds is a technique that has been in use since the early development of pulsed lasers. Efficient laser generation of ultrasounds on metal is performed by sending a strong laser pulse onto the surface of the material, thus causing ablation or vaporization of a small quantity of the material at the point of impact of the laser, as shown in Figure 1.1. Following the ablation, a recoil force is generated, which is the source of a compression (longitudinal) ultrasonic wave. The compression wave propagates in a direction normal to the free surface of the material, i.e., the surface of impact of the laser beam, independently of the angle of incidence of the laser light. Hence, time-of-flight of the traveling ultrasonic pulse is always recorded in the direction normal to the surface.
Figure 1.1: Laser generation of ultrasound in ablation mode
 When ablation of the material is not possible, the power of the generation laser is reduced. The absorption of the laser light then only causes a sharp increase of the temperature of the material near the surface, as shown in Figure 1.2. The temperature gradient will result in the creation of stress near the surface from the resulting thermal expansion of the material. Strong compression (longitudinal) waves will propagate in a direction normal to the surface, while shear (transverse) waves will propagate at an angle dependant on the properties of the material. After a short delay, the thermal energy is diffused within the bulk of the materials, leaving the surface without any damage or noticeable mark.
Figure 1.2: Laser generation of ultrasound in thermo-elastic mode
 Laser detection of ultrasound is based on the demodulation by an optical interferometer of the laser light reflected or backscattered from the surface of the material. In laser detection, a single frequency, high-coherence length, laser light is focused on or near the point of impact of the generation laser beam on the surface of the material. Any surface motion at the point of impact of the detection laser is recorded on the reflected light as a frequency (or phase) variations (Doppler Effect), as shown in Figure 1.3. The ultrasonic surface displacements are therefore "encoded" in the phase of the reflected or backscattered laser light, called the signal beam.
Figure 1.3: Laser detection of ultrasounds
 The basis of optical detection of ultrasound consists of three steps: an ultrasonics-to-optics conversion, an optical phase modulation to intensity modulation process, and finally an optical intensity to electrical signal conversion. The ultrasonics to optics conversion, as described previously, is produced by the surface motion associated with the ultrasonic wave that induces a phase change on the light beam reflected or scattered by the surface.
 Since optical detectors are not sensitive to phase variations but rather to intensity variations, an optical phase-to-intensity conversion is required. An interferometric process performs the conversion. The process is achieved by combining a reference light beam with the signal light beam. The combination of the two beams will then "beat" as a function of the phase difference between both beams. Numerous interferometers have been used to produce the reference beam based on passive interferometric techniques, such as the confocal Fabry-Perot, the use of which has been validated in various industrial environments.
Laser-ultrasonics detection with FPC
 TECNAR's FPC laser-ultrasonic detection unit is based on the confocal Fabry-Perot approach. The principle of detection is to use time delayed images of the light from the target to form the needed reference beam. A Fabry-Perot is an optical system consisting of two mirrors: the front mirror being partially reflective while the second is fully reflective. As shown in Figure 1.4, the signal beam incident to the Fabry-Perot is partially reflected by the front mirror and partially transmitted inside the cavity. The transmitted signal beam then propagates inside the cavity where it is completely reflected by the back mirror. This reflected beam is then also partially transmitted and partially reflected by the front mirror. Therefore, in front of the cavity we have the initial signal beam that interferes with multiple reflections from the cavity.
Figure 1.4: Principle of operation of the FPC
 If there is no phase variation as function of time in the input beam to the Fabry-Perot, then the output beams will add in phase if the cavity length is an integer number of the optical wavelength of the input beam (either 532 nm or 1064 nm depending on the model of the FPC). This can be observed by recording the output optical intensity of the Fabry-Perot as function of the length of the cavity, as shown in Figure 1.5. Each peak in the figure corresponds to a resonance mode of the cavity.
Figure 1.5: Principle of operation of the FPC
 The same result would be achieved if the optical wavelength of the signal beam is swept instead of the cavity length. Since phase variation as a function of time can be viewed as a frequency variation, if the cavity length is set to half-height amplitude (mid-amplitude of the peaks shown in the figure above), any frequency variations will cause a corresponding amplitude variation of the reflected beams intensity, which can then be recorded by a photodetector.
 For proper laser-ultrasonic operation, the cavity length of the Fabry-Perot must therefore be constantly stabilized at a predetermined distance, with respect to the optical wavelength of the detection laser. Any drift of the detection laser optical wavelength must be tracked and accounted for by the cavity of the Fabry-Perot. Also, ambient vibration and mechanical thermal expansion can cause small changes in the cavity length, which must be accounted for.
 TECNAR's FPC is supplied with an internal electronic stabilization loop. The system uses a combination of the reflected beams to obtain a stabilization feedback signal. The feedback signal is sent to a PZT translator mounted at one end of the Fabry-Perot. The PZT translator moves the mirror to adapt the length of the cavity and compensate for any mismatch between the detection laser wavelength and the cavity length in order to achieve optimum sensitivity for laser-ultrasonic detection.
Laser-ultrasonics detection with TWM
 Recently, following developments made at the IMI-NRCC and the Laboratoire Charles Fabry of the Institut d'Optique, Research unit associated to the Centre National de la Recherche Scientifique - France, an active interferometer approach has been introduced based on two-wave beam mixing.
Figure 1.6: Principle of detection with photorefractive crystal
 In this approach, a pump light beam and a signal light beam, which carries the ultrasonic information as phase