Science & Mathematics - 9 August 2007

2007-08-09 04:11:51 · 1 answers · asked by Anonymous in Physics

Hi,
My letters, on the computer's sreen, have suddenly become very small. I can hardly read anything on my computer.
Could anybody explain me how to change it to normal size?
Thank you.

2007-08-09 04:10:47 · 6 answers · asked by Anonymous in Other - Science

A Norman window has the shape of a rectangle surmounted by a semicircle of diameter equal to the width of the rectangle. If the
perimeter of the window is 20 ft, what dimensions will admit the most light (i.e. maximum
area).

2007-08-09 04:10:23 · 2 answers · asked by no idea 2 in Mathematics

• if the system accelerates 2.3 m from rest, how much work is done by gravity on the system?
• How can I use the definition of KE to identify the velocity of the system after having moved through the 2.3 m assuming that the system was released from rest.

so we have

m1 = 1 kg
m2 = 1.06 kg
x = 2.3 m
v0 = 0

2007-08-09 04:09:18 · 1 answers · asked by e=mc^2 1 in Physics

(13)
Can the graph of a rational function have both a horizontal and an oblique
asymptote? Explain.

2007-08-09 04:08:56 · 2 answers · asked by no idea 2 in Mathematics

2007-08-09 04:08:40 · 2 answers · asked by black 1 in Engineering

We have demonstrated for the first time that inhalation of common air pollutants affects the systemic vasculature of humans. Short-term exposure to PM2.5 and O3 at levels that occur in urban environments causes acute conduit artery vasoconstriction without producing immediate alterations in endothelial-dependent or -independent vasomotion. This finding is important because it suggests that alterations in arterial tone may be a relevant mechanism contributing to air pollution–mediated acute cardiac events and because it provides evidence that the observations shown by large epidemiological studies are biologically plausible.1

Relevance of Conduit Artery Vasoconstriction
It is reasonable to suspect that the coronary vasculature may respond similarly to air pollution exposure because brachial and coronary reactivity strongly correlate (r=0.79, P<0.001 for brachial versus coronary FMD).10 Even so, a reduction in coronary diameter of this relatively small magnitude (0.1 mm) would have minimal impact on healthy adults. However, congruent with epidemiological findings that individuals at increased risk for acute air pollution–related cardiac events generally have pre-existing cardiovascular disease, 2 this degree of sudden coronary vasoconstriction could promote cardiac ischemia in those with underlying flow-limiting obstructive lesions or could trigger instability of susceptible plaques.11 Furthermore, the vasculature of patients with coronary risk factors is known to hyper-react to a variety of vasoconstrictors,12,13 which potentially increases their susceptibility for acute cardiac events after air pollution exposure. Additional investigations in the coronary circulation and in high-risk individuals are needed to confirm these hypotheses.

Mechanisms and Mediators of Vasoconstriction
Because this is the first study to investigate the effects of air pollution on the vasculature, a more complete understanding of the pathophysiological mechanisms underlying our observations and the specific pollutants involved requires further investigation. Substantial evidence links increased PM2.5 alone with cardiac mortality.1 However, our initial air pollution exposure was chosen to be PM2.5 plus O3 because this mixture occurs in "real-life" settings. At present, an effect on the vasculature partially mediated by O3 cannot be ruled out. Determinations of the relative importance of PM2.5 versus O3 and specific components in fine particulate matter await follow-up studies now that a meaningful effect of urban air pollution on vascular function has been demonstrated.

Potential biological mechanisms for the vasoconstriction include a reflex increase in sympathetic nervous system activity via stimulation of pulmonary vagal afferents14 or an acute increase in vascular ET release, analogous to cigarette smoking.15 PM2.5 inhalation has been shown to induce systemic inflammation and cytokine production,16 possibly related to free radical activity of components in particulate matter.17 In turn, these have the capacity to enhance vascular ET expression by direct mechanisms or via activation of oxidative stress pathways.6 Indeed, we have previously demonstrated the presence of increased plasma ET levels acutely after PM2.5 exposure.5

In conclusion, alterations in arterial tone and reactivity in response to PM2.5 and O3 exposure is a new arena for future research into the biological mechanisms linking air pollution with acute and potentially chronic cardiovascular events. Further investigations are needed to confirm and extend our findings to the coronary circulation and to subjects with existing heart disease.

2007-08-09 04:03:29 · 1 answers · asked by Anonymous in Biology

What is the orbital KE of a satellite of mass 560 kg in circular orbit about a planet of mass 21 * 10 ^ 24 kg, orbiting at a distance of 47700 km from the center of the planet?
(G = 6.67 * 10 ^ -11 N m ^ 2 / kg ^ 2)

It also asked what would be the PE.

My question is pertaining to my formulas.
To determine the velocity I used
V = square root of ( G * M * m / radius )
KE = .5 * M * m * v ^2
PE = - G* M * m / R

M = mass of planet, (21 e 24 kg)
m = mass of satellite 560 kg
R = 47700 km

2007-08-09 04:02:57 · 1 answers · asked by Anonymous in Physics

I think we should paint a big picture of Bob Marley's face on the side of the space shuttle. We could play reggae during the blast-off! Isn't that cool? What do you think?!!!

2007-08-09 03:47:15 · 9 answers · asked by Anonymous in Astronomy & Space

If anyone could explain how the following is done step by step, it would be greatly appreciated!

Find the volume of the solid that lies below the surface z = f(x,y) and above the region in the xy-plane bounded by the given curves.

z = 9 - x - y; y = 0, x = 3, y = (2/3)x

2007-08-09 03:44:42 · 2 answers · asked by Anonymous in Mathematics

im looking for detaails about the 2 moon situation that is making news globally. i know its taking place on august 27, but what time is it for people in france (specifically la rochelle)? im dying to know. thx!

2007-08-09 03:43:44 · 11 answers · asked by Luvin Usagi 2 in Astronomy & Space

Plz explain lucidly.

2007-08-09 03:38:05 · 5 answers · asked by Aqua 2 in Physics

Anyone know any infrastructures that are U-shaped, or shaped like a parabola? Please do help me. I need it for my project.

Thanks a lot!

2007-08-09 03:35:01 · 4 answers · asked by Belx2 2 in Engineering

I have a brainteaser that I need an answer for.
You have exactly 100 dollars to spend and you must buy exactly 100 head of cattle.
Bull are 5.00 each
cows are 2.50 each
calves are .10 each.
I need to know how many of each to buy to make eactly 100 dollars and have 100 animals.

Thank.

2007-08-09 03:29:23 · 5 answers · asked by Anonymous in Mathematics

Using the tolerance as for minimum or maximum resistance values of the resistor? could you give me some example please? tanku.

2007-08-09 03:26:06 · 3 answers · asked by Redrope 1 in Engineering

the potential energy of an object is given by U(x)= 3x^2-2x^3, where U is in joules and x is in meters.
a. determine the force acting on this object.
b. at what positions is this object in equilibrium/
c. which of this equilibrium positions are stable and which are unstable?

2007-08-09 03:20:51 · 1 answers · asked by la 1 in Physics

When any body is released from infinite distance on a planet then
it aquires the speed equal to escape velocity of that planet.It can be simply derived by using concept of integration.Now my question is that when a body is released from infinite distance on the black hole will it aquire the escape speed of black hole which is greater than speed of light?

2007-08-09 03:16:06 · 14 answers · asked by pradyumna k 1 in Astronomy & Space

2007-08-09 03:13:53 · 4 answers · asked by Anonymous in Geography

Mendeleyev's Dream, when I read this I seriously, seriously thought about changing my career.

2007-08-09 03:13:52 · 2 answers · asked by Anonymous in Chemistry

2007-08-09 03:12:48 · 3 answers · asked by Miles 1 in Chemistry

any specific molecular compounds?

2007-08-09 03:12:15 · 3 answers · asked by kd yo 1 in Chemistry

2007-08-09 03:09:25 · 3 answers · asked by jackson 2 in Chemistry

If the world rotates every 24 hrs, one should be able to go up, hover, then come down and be in India in about 12 hrs. Do we need to be in space where the earth's gravity and atmosphere have less of an effect on us?

2007-08-09 03:08:53 · 13 answers · asked by FX 1 in Astronomy & Space

2007-08-09 03:07:57 · 2 answers · asked by jrzedvl 1 in Chemistry

2007-08-09 03:07:53 · 5 answers · asked by Flex 1 in Earth Sciences & Geology

2007-08-09 03:07:42 · 2 answers · asked by kiran d 1 in Physics

Or maybe just unfortunate objects in the way? How does the lost charge in the thundercloud get replaced?

2007-08-09 03:06:11 · 6 answers · asked by duh 2 in Physics

I have a group project online to do and don't understand exactly what I am supposed to do. We have to create a new town named Luca with a population of 3,942. I have to graph the Growth Model by Radical Equation. Please Help! If you need additional information let me know. I really need this done!

2007-08-09 03:04:37 · 3 answers · asked by Anonymous in Mathematics

if parallel universes and dimensions exsists? could it be that there is an infinite barrier separating our dimensionsfrom this gap and could high speed particles go surpass this barrier?

2007-08-09 03:02:51 · 5 answers · asked by Mel M 2 in Astronomy & Space

Which planet has a longer day than year?

2007-08-09 03:02:11 · 6 answers · asked by Anonymous in Astronomy & Space