Biraz fizik..biraz web

Tek arkaplan resmiyle yuvarlak kenarlı tablolar

Bora Canbula — Fri, 18 Apr 2008 06:08:56 +0000

Bu yazıda tek bir daire resmi ile yuvarlak kenarlı tablolar yapmayı anlatmaya çalışacağım..tabi bunu yapmak için css’den faydalanacağız..kullandığım resim aşağıdaki daire resmi

bu resim 30×30 piksel boyutunda ortası #336699 renginde basit bir daire ve yuvarlak kenarlı şık tablolar yapmak için ihtiyacımız olan tek şey şimdi de kodlarımıza geçelim..

tablomuzun üst tarafını oluşturan kodlarımız şöyle..burada sol üst köşe için dairemizi sol üste hizaladık ve genişlik ve yükseklik değerlerini 15 piksel vererek sadece işimize yarayan kısmının görünmesini sağladık zira sağ üst köşe için dairemizi sağ üste hizalayıp yine aynı boyut ayarlamasını yapacağız..orta bölümde ise sadece arkaplan rengini dairenin içiyle aynı renkte vermemiz yeterli

bu kısımda tablomuzun içeriğini yazabiliriz..ben örnek bir şeyler yazdım



sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

alt kısım ise üst tarafta yaptıklarımızın tam tersi..burada dikkat ettiğimiz nokta daireleri hizalarkan top değil bottom kullanıyoruz yani alt köşelere hizalıyoruz

sonuç ise şöyle olacak..vay be tek resimde işi bağladık

sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd
sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd
sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd
sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd
sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd
sdmklas dmkasl dmacvsd vasd vasdv asd vasdv asd vsdv asd vd vasdv asdv asd vasd

Finding The Higgs Boson

Bora Canbula — Thu, 17 Apr 2008 19:56:25 +0000

Is the imperative of the two most powerful particle accelerators ever built—the Tevatron at Fermilab, now reaching the peak of its decades-long performance, and the Large Hadron Collider (LHC) at CERN, where beams will circulate for the first time around a 27-km track within the next few months. The Higgs has not yet been discovered, but at this week’s meeting of the American Physical Society (APS) in St. Louis dozens of talks referred to the status of the Higgs search. Why is the Higgs so important? Because it is thought to pervade the universal vacuum; not, as with the old aether, to provide a material substrate for the propagation of electromagnetic waves, but rather to interact with particles and confer mass upon them.

The Higgs’ ministrations are usually hidden away in the vacuum, but if enough energy is brought to bear in a tiny volume of space—at the point where two energetic particles collide—then the Higgs can be turned into an actual particle whose existence can be detected. Theoretical calculations made using the standard model of particle physics combined with previous experiments serve to limit the possible range of masses for the Higgs particle. Right now that mass is thought to be larger than 114 GeV but smaller than about 190 GeV.

The Tevatron delivers more than enough energy to create a particle in that energy range. The main issue, then, is luminosity, or the density of beam particles crashed together per second. The Tevatron recently established a record high luminosity: 3.1 x 10^32 per cm^2 per second. What would a Higgs event look like? One speaker at the meeting, Brian Winer (Ohio State), said that the “most Higgs-like Higgs event” seen so far was one in which (it is surmised) the proton-antiproton collision at the Tevatron had created a fireball which then decayed into a W boson (one of the carriers of the weak nuclear force) and a Higgs particle.

The Higgs in turn quickly decayed into a bottom-antibottom quark pair whose combined mass amounted to 120 GeV. By itself such an event does not constitute a discovery. Successfully observing the Higgs involves finding an inventory of candidate events substantially larger than the number of expected background events from collisions which do not produce a Higgs particle but which mimic some features of the Higgs. Time (and luminosity) will tell whether the Tevatron accumulates enough Higgs candidate events to establish a statistically-satisfactory “discovery.”

One Tevatron physicist, Dmitri Denisov (denisovd@fnal.gov) summarized the likely status of things when the experiments (the CDF and D0 detector groups) start to wrap up in the year 2010. The luminosity, he said, would probably be twice what it is now and that 4 to 8 times more data would be analyzed than is available today. The Higgs, if it exists, is expected to show up in abundance at the LHC, where the collision energy is much higher than at the Tevatron. Abraham Seiden (abs@scipp.ucsc.edu) of UC Santa Cruz summarized the current status of the LHC.

In the CERN lab scientists and engineers are now chilling down the magnets which steer protons around their proper trajectory to the near-absolute-zero temperatures needed for operating in a superconducting mode. Although designed to produce proton beams at 7 TeV, the accelerator will at first hold to a more conservative 5 TeV. As for the present schedule, Seiden quoted a recent CERN report specifying mid June as the time when the machine would be cooled and ready to circulate beams around the ring and August as the time when actual particle collisions will commence. However, several scientists at the meeting, when asked, were somewhat skeptical that this timeline would be met.
As for the prospective scenario for discoveries at LHC in coming years, Seiden said that finding evidence for a supersymmetric particle (one of a large family of hypothetical particles) might be possible as early as the year 2009, while finding the Higgs might be possible by 2010.

Optical Clocks Get Better

Bora Canbula — Thu, 10 Apr 2008 20:24:15 +0000

Two separate experiments in Colorado compare the frequency of emissions from atoms or ions to an uncertainty of 10^-16 or better. Earlier atomic clocks operated by reading out the movements of internal transitions from one quantum state to another in cesium atoms; the light emitted was in the microwave range. With frequency comb techniques (http://www.aip.org/pnu/2008/split/853-1.html) measurement of optical-range frequencies can also be made with high accuracy.

In the 28 March 2008 issue of Science two groups reported new superb levels of precision. One experiment, carried out by a JILA/Colorado/ NIST-Boulder team (Ludlow et al.), gauges the uncertainty of a clock based on neutral strontium atoms to a level of 10^-16 by comparing it to a clock using calcium atoms and located a kilometer away. The other experiment, carried out at NIST-Boulder (Rosenband et al), looks at two clocks 100 meters apart.

The clocks contain respectively a single aluminum and a single mercury ion. The fractional uncertainty in the ratio of the frequency outputs for the clocks was determined to be 5.2 x 10^-17. (NIST information at http://www.nist.gov/public_affairs/releases/logic_clock/logic_clock.html and http://www.nist.gov/public_affairs/clock/clock.html )