In tandem with the exhibition, a panel discussion, free and open to the public, will be held March 9 at 4PM at the Austin Central Library. It will explore the role of the UNESCO Creative Cities Network (UCCN) and the individual and joint initiatives of its member cities and their communities to promote digital artmaking.
Immersive media exhibitions have become highly popular in recent years, showing much success in attracting and engaging audiences. Media artists have unprecedented new opportunities but also face unique challenges. These demands include securing funding, fabricating complex artwork, creating work that can tour, and maintaining tech-dependent art. At the moment, there are few organizational or informational sources of support for media artists. In order to fill this gap, media artists and arts administrators from UNESCO Media Arts cities around the world will gather to share their lessons about how to navigate and thrive in this new art landscape.
In 2015, Austin achieved the distinction of being the first (and only) city in the United States to receive a "City of Media Arts" designation from UNESCO (United Nations Educational, Scientific, and CulturalOrganization). The designation underscores Austin's reputation as a trendsetting global city at the intersection of art, music, and digital technology, and an international hub for creative exchange.
From individual artists to wide-ranging arts organizations, Austin has a rich and diverse cultural ecosystem. The city is recognized for its innovation and leadership in industries including music, film, gaming, and multidisciplinary digital experiences, and festivals such as South by Southwest (SXSW), Austin City Limits and the Fusebox Festival have made Austin a premiere cultural destination.
As a member of the UNESCO Creative Cities Network (UCCN), Austin works individually and in partnership with other UNESCO cities to promote creativity and cultural industries, strengthen participation in cultural life, and assure the integration of culture into urban development plans.
To learn more about Austin's UNESCO designation and activities, click the image below.
Image: Jacob Villanueva and Sue Lambe (top row, first and second from left) with other delegates at the Media Arts Festival.
Each year, Changsha, China, a fellow UNESCO City of Media Arts, hosts the Changsha Media Arts Festival. Sponsoring delegates from around the globe, including those from the UNESCO Creative Cities Network (UCCN), the Changsha Festival highlights the city's innovation in the media arts and serves as a platform for global exchange to further this field.
In May, Jacob Villanueva, a local artist working in media arts, represented Austin at the international event, accompanied by Sue Lambe, Art in Public Place Program Manager. We sat down with Jacob to learn more about his trip and what lessons we in Austin could learn from his experience.
Jacob, how and why were you selected for this trip?
I currently serve on the Art in Public Places Panel and the UNESCO Advisory Committee for the City of Austin. I have a wide range of experience in various media arts and, in my role as panelist and committee member, I assist with making artistic decisions for the city. At the suggestion of Mayor Pro Tem Tovo, and with support of the Cultural Arts Division, I accepted the invitation to represent Austin's media arts community in Changsha and welcomed the opportunity to see how global cities are currently supporting media arts.
What surprised you most about arts and culture in Changsha?
It was surprising to see how strongly ancient Chinese arts influence the newer art forms in China. The level of craft and detail of Chinese arts of the past continues to carry through to more contemporary arts.
Like Austin, Changsha is a UNESCO media arts city. How were media arts integrated into their city and cultural community?
During my visit to Changsha, I was exposed to a wide range of traditional crafts and newer media arts. The simple dialog of describing media arts in Changsha led me to believe that there isn't much of a distinction between traditional and new media arts there. The arts, collectively, are woven together. Conversations about a traditional craft such as ceramics had the same level of prestige or importance as newer media.
Were there any activities or programs that you saw that could be retooled and implemented in Austin?
Changsha has an interest in developing more exchanges with global artists and I think this is a great idea for Austin to explore. I got some of the most important visual information from going through the museums and performances, but it was the exchange and sharing of ideas from people in the community that was the greatest benefit of my experience there.
The Cultural Arts Division and SXSW have joined forces to develop an annual UNESCO Media Arts Showcase at SXSW. The inagural showcase was hosted March 12-13, 2018 as an official part of SXSW's art program and its new Cities Summit. The showcase comprised a mini-exhibition of media art installations and a companion panel discussion highlighting the global initiatives of the UNESCO (United Nations Educational, Scientific and Cultural Organization) Creative Cities Network.
In tandem with the exhibition, a panel discussion was held March 12, 2018 at the Four Seasons. The session explored the role of the UNESCO Creative Cities Network and the individual and joint initiatives of its members to promote creativity and cultural industries, strengthen participation in cultural life, and assure the integration of culture into urban development plans.
As part of the City of Media Arts cluster, Austin participates in international UNESCO exhibitions.
Vurv Collective (Kevin Reilly) represented Austin at the Gawngju Cultural Foundation Artist Exchange Exhibition in December 2017. The exhibition featured works from several other UNESCO Media Arts Cities and was held in conjunction with the 2017 Gwangju Cultural Foundation Meeting, which City staff attended.
Artist Clay Odom (Studio Modo) represented Austin at the UNESCO "Data City" exhibition in Enghien-les-Bains, France, April-July 2017. The exhibition featured works from several other UNESCO Media Arts Cities and was held in conjunction with the 2017 Creative Cities Annual Meeting, which CAD staff attended.
Check out this video for an overview of Austin's many media arts initiatives.


They are such a pleasure. They have such a sweet loving disposition, yes even the bulls! Only growing to approx. 42" at the hip when full grown, Mini Herefords are perfect for a small farm. Because of their small stature, you can raise 4 cows of 1 acre of pasture! You can easily divide your field into two or four paddocks and rotate your livestock as needed so as not to overgraze. By the time the cattle have grazed through the last one, the first is ready to be grazed again. The more paddocks, the more often you can move your cattle to fresh pasture. Since the animals will spend a week or more in each paddock, a water trough can be placed where the corners of several paddocks come together to serve them all.
For You: No antibiotics or hormones, lower in fat, calories and cholesterol, higher in beta-carotene, vitamin E, conjugated linoleic acid and omega-3 fatty acids (research shows these nutrients can play a part in reducing cancer, cholesterol, diabetes, high blood pressure and heart disease).
For the Environment: Reduced soil erosion and improved air and water quality, reduced greenhouse gases and global warming, improved habitat and forage for wildlife.
For the Cow: Raised naturally with fresh grass, air and water. Raised in a low-stress environment and humanely treated. Raised healthy, peaceful and natural. Free from antibiotics and growth hormones.


During its first few years, funding was of the utmost importance for Clean Energy Fuels . If the proposed stock sale by Chesapeake Energy had happened back then, it might have spelled doom for the nascent business. Now, however, some of the biggest companies in the world are buying into Clean Energy's vision for a cleaner driving America.
Just recently, FedEx CEO Frederick Smith professed that he sees a major shift for fleet vehicles toward liquified or compressed natural gas over the next 10 years. This support is huge given FedEx's fleet of around 90,000 vehicles. He was also outspoken about the need for the U.S. to approve exports of LNG, one of the few CEO proponents not employed by the energy sector.
T. Boone Pickens' brainchild is gathering momentum. Should you climb on board?
More details can be found in the video below.
The article Don't Fret Chesapeake's Sale of Clean Energy Stock originally appeared on Fool.com.
Joel South has no position in any stocks mentioned. Taylor Muckerman has no position in any stocks mentioned. The Motley Fool recommends Clean Energy Fuels, FedEx, and United Parcel Service. The Motley Fool has the following options: Long Jan 2014 $20 Calls on Chesapeake Energy, Long Jan 2014 $30 Calls on Chesapeake Energy, and Short Jan 2014 $15 Puts on Chesapeake Energy. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.


text:
Echo of a Song
By Brian Shivers - October 19, 2011
"Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight and the sin that clings so closely, and let us run with perseverance the race that is set before us, looking to Jesus the pioneer and perfecter of our faith." Hebrews 12:1-2
In 1996, I traveled with several students from Second Presbyterian Church to Santa Fe, NM where we worked on a small community farm sponsored by the local Presbyterian Churches. This farm, supported by volunteers, gave 100% of its produce to the homeless shelters in the area. The trip was more than any of us could have expected or imagined.
While in Santa Fe, we stayed at Saint Catherine Indian School, a boarding school founded in 1887 to provide Native American youth with a quality education. One afternoon on a quick return trip from the work site to the school, I had the opportunity to meet a Native American man who was walking across the campus. His name was Bob Chavez. He was the art teacher at the school.
After some small talk, Mr. Chavez invited into a quaint gift shop where the school sold pens, pencils, shirts, postcards, posters and the like to raise extra morning to support the school. Some of the cards and posters were adorned with pictures of the school or the beauty of the surrounding area. Other cards were graced with beautiful southwestern art. I inquired about the artwork which sparked this incredible story.
Bob, a Native American from the Conchiti Pueblo, told me that he served in World War II as a member of the New Mexico National Guard. He and 1800 of his comrades were taken captive in Japan. He survived four cruel years as a prisoner of war which included the brutal Bataan Death March that saw thousands of Filipino and American soldiers die. Bob said that while he was in the prison camps, he made a promise to the Great Spirit that if he survived, he would devote himself to his school, St. Catherine's Indian School, where he was a member of the first graduating class in 1935.
When he returned to New Mexico after the war, Bob made good on his promise. For over 50 years, he volunteered his time and considerable talent introducing art and track and field to the school. It was his artwork, produced in his simple art studio on St. Catherine's campus that adorned the posters and postcards sold in the gift shop.
Bob, whose Indian name given by his grandmother is Ow-u-te-wa, means "echo of a song." Bob passed away in 2002, and his life and work were honored by all who knew him. Manuel "Bob" Chavez has been and will continue to be the echo of God's song of faith, grace and love to countless Native American boys and girls and one youth minister from Indianapolis, Indiana.
Your life is also an echo of this song of grace. May others be blessed by its reverberations as they witness your life and give glory to God. Allow your life to SING!
Second Testament stories

redpajama_set_name: RedPajamaCommonCrawl


text:
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Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5
Saikat Mukhopadhyay1,
Lucas Lindsay1 &
David J. Singh2
Scientific Reports volume 6, Article number: 37076 (2016) Cite this article
Electronic properties and materials
The lattice thermal conductivity (κ) of hexagonal Ge2Sb2Te5 (h-GST) is studied via direct first-principles calculations. We find significant intrinsic anisotropy (κa/κc~2) of κ in bulk h-GST, with the dominant contribution to κ from optic phonons, ~75%. This is extremely unusual as the acoustic phonon modes are the majority heat carriers in typical semiconductors and insulators. The anisotropy derives from varying bonding along different crystal directions, specifically from weak interlayer bonding along the c-axis, which gives anisotropic phonon dispersions. The phonon spectrum of h-GST has very dispersive optic branches with higher group velocities along the a-axis as compared to flat optic bands along the c-axis. The large optic mode contributions to the thermal conductivity in low-κ h-GST is unusual, and development of fundamental physical understanding of these contributions may be critical to better understanding of thermal conduction in other complex layered materials.
Phase change memory devices exploit thermally induced transformations between different phases of phase change materials (PCMs) where thermal and thermoelectric properties of PCMs are of central importance. Ge2Sb2Te5 (GST), a prototypical phase change material, has been widely studied1,2,3,4,5,6,7,8,9,10 in this context due to its fast switching speed11 and large changes in electrical and optical properties upon phase transformation. Recently, Lee et al.5 reported anisotropic thermal conduction of GST thin films with in-plane film values significantly different from cross-plane film values for cubic and hexagonal phases and noted a varying conductivity with annealing time of the samples. They reported that cross-film conduction is favored by up to 54% due to thermal resistance of amorphous regions near grain boundaries5. All of the GST phases (cubic, hexagonal and amorphous) exhibit low thermal conductivity, and it has been shown that the thermal properties in thin film samples vary significantly with sample thickness attributed to boundary scattering and microstructure8. As thin film samples have varying degrees of extrinsic defects and microstructure, it is not clear whether there is intrinsic thermal conductivity anisotropy in bulk h-GST, anisotropy due solely to the hexagonal structure. In addition, h-GST has been shown to exhibit good thermoelectric properties12,13,14, though thermal conductivity studies particularly in bulk h-GST are limited.
Identifying mechanisms for obtaining low thermal conductivity and modification of materials to obtain it, e.g., by nanostructuring and alloying, is an important part of thermoelectrics research. This typically focusses on scattering of heat carrying acoustic phonons15. Optic phonon contributions are often negligible due to their typically low group velocities and short lifetimes16,17, even in cases where they comprise a large fraction of the total modes in complex crystals. An exception is the nuclear fuel, UO2, where the longitudinal optic branch was reported to be important18. Recently it has been shown that optic mode contributions can become important in other materials of interest for thermoelectric applications, e.g., PbTe (22%) and PbSe (25%)19, Mg2Si (30%) and Mg2Sn (18%)20. Here we examine the lattice dynamical properties of h-GST from first principles and connect these to its lattice thermal conductivity by direct calculations. We find κ values consistent with measured data. Importantly we find that in h-GST the optic phonons are the dominant heat carriers (~75%) at room temperature, and that these modes significantly affect the behavior of κ for different transport directions. We find significant intrinsic thermal conductivity anisotropy arising from the hexagonal structure and optical phonon contributions. This anisotropy may be of critical importance in phase change devices that contain h-GST in the crystalline phase with preferential orientations for crystallization.
We compare the calculated phonon density of states (PHDOS) with the measured Raman spectra21 of polycrystalline hexagonal GST films at 673 K and 773 K in Fig. 1. Two distinct peaks were measured at 3.2 THz (peak-A) and 5.1 THz (peak-B) and also appear in our calculation. Peak-A, reported to be the vibration of the heteropolar bond in the tetrahedral GeTe4 and pyramidal SbTe3 21, compares well (3.11 THz) with our calculation, however, the frequency of peak-B is underestimated (4.79 THz) by our calculation. A similar underestimation of the peak-B frequency (5.01 THz) was also reported in a previous theoretical work by Sosso et al.22 Regardless, this demonstrates the relative accuracy of the harmonic force constants in our calculations. We also note that the calculated PHDOS here compares well with the previously reported PHDOS from a first-principles calculation23 with slightly different acoustic velocities. These small variations likely arise from different DFT approximations employed [LDA23 vs. GGA (this work)] as LDA (GGA) typically gives shorter (longer) bonds, thus higher (lower) sound velocities. However, our calculated sound speed of the longitudinal acoustic mode 3.7 km/s (3.2 km/s) along a-axis (c-axis) compares well that measured in experiment (3.3 km/s)6.
Comparison of phonon density of states (normalized) at Γ along with the measured Raman spectra 21 at 673 K (orange circles) and 773 K (green circles).
The calculated κ as a function of temperature is given in Fig. 2(a), which clearly shows a strongly anisotropic κ along the two crystal directions: a- and c-axis. This is of potential importance for devices with h-GST (the crystalline phase in devices can be either h-GST or cubic GST) because strain, thermal gradients, directional growth, and interaction with substrates and interfaces can all lead to preferential alignment of the crystal axis, which in combination with the thermal conductivity anisotropy will affect device behavior. Furthermore, if controlled, it may provide another pathway for improving performance. As shown in Fig. 2(a), κ at 300 K for h-GST along the a-axis (1.67 W/m-K) is nearly twice of that along the c-axis (0.86 W/m-K). This anisotropy (κa/κc~2) persists throughout the entire temperature-range of this study. The magnitude of the anisotropy is similar to that found for layered Bi2Te324,25,26 and higher than that of manganese silicide (HMS)27. While significant bonding anisotropy was held responsible for the anisotropic κ in Bi2Te328 with van der Waals gaps in the low κ direction, a low-energy (<10 meV) twisting phonon and anisotropic group velocity of the optic phonons were found responsible for the observed κ anisotropy in HMS27. We note that Lee et al.5 measured an anisotropic κ favoring cross-film conductivity in polycrystalline h-GST thin films. Crystal orientation relative to the film may not be commensurate with a- and c-axis alignment and the anisotropy in experiment is attributed to amorphous regions near columnar grain structures in the films. The anisotropy reported here is due to intrinsic properties of the hexagonal crystal structure, thus direct comparison of these anisotropy mechanisms is not possible. In the following, we elaborate on the origin of the intrinsic anisotropy of κ in h-GST, and on the surprisingly large κ contribution from the optic phonon modes.
(a) Lattice thermal conductivity and (b) accumulated thermal conductivity with phonon frequency of h-GST along a-axis (red) and c-axis (blue). The contributions from optic and acoustic modes to total κ at 300 K along a- and c-axis are shown in the inset of Fig. 2(a). A schematic of the unit cell of h-GST is also shown in the inset of Fig. 2(b).
Firstly, the calculated κ for both crystal directions in Fig. 2(a) give the typical T−1 behavior, characteristic of Umklapp scattering, up to the highest temperature considered (T = 800 K). This is at variance with roughly T independent thermal conductivity measured by Lyeo et al.6. Further, the reported thermal conductivity (1.53 W/m-K)6 of thin film (270 nm) h-GST at 673 K is significantly higher than the calculated κ values given here: 0.75 and 0.39 W/m-K for the a- and c-axis, respectively. This discrepancy is likely due to a significant electronic contribution to the total thermal conductivity as h-GST has a relatively small band gap [~0.5 eV]29 in combination with a low lattice thermal conductivity. Using the Weidemann-Franz law coupled with electrical conductivity measurements, Lyeo, et al.6, estimated the electronic contribution to the total thermal conductivity was ~70% giving an estimated lattice contribution of 0.43 W/m-K at 673 K. Increasing electronic contribution to the total thermal conductivity would compensate the decreasing lattice thermal conductivity resulting from enhanced phonon-phonon scattering with increasing temperature, resulting in the T independent thermal conductivity behavior observed for h-GST in experiment. The calculated average κ (0.63 W/m-K) overestimates the measured value likely due to extrinsic scattering, e.g., grain boundaries and impurities. Further, the thermal conductivity of thin film h-GST is sensitive to sample thickness8. For instance, Reifenberg et al. measured a thermal conductivity (electron + phonon) of 350 nm h-GST thin films that was more than twice of that in samples with thickness of 60 nm8. Given the thickness of the samples in ref. 6 were 270 nm, this may also explain the overestimated calculated κ as compared to measurement. We estimated the effect of grain boundaries on κ using a simple empirical model for diffuse boundary scattering and found an increase of 11% in κ for a boundary scattering length of 350 nm as compared to that for a scattering length of 60 nm. We note that our calculations do not include the effects of boundary scattering on the electronic contribution to the thermal conductivity. Nevertheless, the focus of this study is to understand features of the intrinsic lattice thermal conductivity of h-GST, therefore, extrinsic scattering and the electronic contribution to κ are not considered further.
The accumulated thermal conductivity with phonon frequency [Fig. 2(b)] for the a- and c-axis demonstrates isotropic κ up to ~0.8 THz with a significant anisotropy in accumulated κ above this. This is precisely where the acoustic and optic phonon branches start to cross and the acoustic branches reach the zone boundary along the c-axis direction. Figure 3 compares the phonon dispersions for the a-axis (Γ → M direction) and c-axis (Γ → A direction) for h-GST. Firstly, we note that the overall acoustic frequency scale is comparable to other thermoelectric materials (lower than PbTe, Mg2Si and Mg2Sn; similar to Bi2Te3), partly due to the large masses of the constituent atoms and partly because of the similarity in bonding to PbTe and Bi2Te3. This gives lower velocity acoustic phonons and enhanced phonon-phonon scattering. The slopes of the dispersion curves give the phonon velocities, important in determining κ. More importantly, we note that the total κ consists of a dominant contribution from the optic modes for both crystal directions. While the conventional heat carriers, acoustic modes, give 25% (20%) of total κ along the a-axis (c-axis), 75% (80%) of the total κ is carried by optic modes [inset in Fig. 2(a)]. This is unconventional as optic mode contributions are not reported to give more than 25%19,20 of the total κ, and are typically much smaller. This warrants further investigations of thermal transport in low-κ materials with many low frequency optic branches.
Phonon dispersions of h-GST along the a-axis (red) and the c-axis (blue).
The phonon dispersion of h-GST shows an inherent anisotropy with highly dispersive optic branches (large group velocities) along the a-axis in contrast to flat optic branches along the c-axis. Further, the acoustic braches along the c-axis do not cross the low-lying optic modes apart from the zone boundary, while the acoustic branches along the a-axis undergo multiple crossings. This is largely a consequence of the smaller Brillouin zone along the c-axis. This is similar to GaAs/AlAs superlattices where the constituting n-units of bulk GaAs and AlAs were arranged along the growth axis so that the edge of the Brillouin zone along the growth direction is as far from the zone center as it is along a- and b-axis30. This was reported to significantly reduce the group velocities of optic modes along the c-axis. Importantly, the acoustic mode velocities near the zone center have little anisotropy and therefore elastic differences are not the origin of the thermal conductivity anisotropy, as will be discussed in more detail below.
To further evaluate the character of the phonon dispersions the projected phonon densities of states for the various atomic species are given in Fig. 4. The lowest frequency modes are predominantly from vibrations of the heavy Sb and Te atoms, with strong contributions from Ge-Te modes starting at ~2 THz. This leads to two prominent peaks in the density of states, the first of Sb-Te character from ~1–1.5 THz, and the second of Ge-Te character from ~ 2–2.5 THz. The higher optic branches have mixed Ge-Sb-Te character extending all the way to the top of the spectrum. It is striking to note the differences in projected phonon DOS along a- and c-directions. Although in the low frequency region, the vibrational modes (acoustic modes) along these crystal directions are similar, the vibrational modes in the higher frequency region (optic modes) are very different. While the optic modes along the c-axis are mostly stretching and anti-stretching modes consisting of Ge-Te and Sb-Te atoms, the optic modes along a-axis are notably more complex and include torsional and twisting modes in addition to the stretching and anti-stretching modes. This is due to the significantly stronger contribution from Te and Sb atoms along the a-axis at frequencies higher than 2.5 THz (Fig. 4).
Phonon density of states projected on individual atoms of h-GST along a-axis and c-axis.
While acoustic velocities are generally considered to be central to conductivity anisotropy, especially for low-κ systems like h-GST, we find no significant anisotropy in the group velocities. We calculated the average acoustic sound velocity along each direction using: Along the a-axis vavg = 2.87 km/s compared to 2.75 km/s along the c-axis, failing to explain the noted anisotropy of κ in Fig. 2. Therefore, it can be anticipated that the higher group velocities of the more dispersive optic bands along the a-axis as compared to the flat bands along the c-axis are responsible for the κ anisotropy in h-GST, especially since these modes govern the thermal transport behavior in this system.
In order to support the above statement, we plot the frequency-dependent averages of each component of the group velocity in Fig. 5. This is similar to the density regression estimates over all branches along the a- and c-axis27:
Calculated average group velocity components along the a- and c- axes as a function of frequency.
where α sums over all modes, q sums over all lattice vectors in the Brillouin zone, is the group velocity along the μ-direction and gα(ω) is phonon density of states.
As can be found in Fig. 5, the average group velocities of the optical modes (>1 THz) are appreciable in both crystal directions, and surprisingly the group velocity of the low lying optic branches surpasses that of the acoustic branches. We note that even the highest frequency optic phonons in the a-direction are significantly dispersive. Often optic modes are not considered as heat carriers because their velocities are small compared to their acoustic counterparts. In fact, we find the opposite is true in h-GST: the optic modes contribute 75% (80%) to κ along the a-axis (c-axis). Not only that, we also find notable anisotropy in group velocities of optic modes along the two crystal directions. While the group velocities of low lying TO modes along the a-axis dominate over that along the c-axis in the frequency range 1–1.5 THz, the opposite occurs around 2 THz. Moreover, the group velocities of the highest-frequency optic modes (>3.5 THz) along the c-axis are very small compared to that along the a-axis. Given that the anisotropy in the acoustic group velocity is not significant, these may very well explain the noted κ anisotropy provided the anharmonicities (as measured by mode Grüneisen parameters here) associated with these optic modes are not so high as to completely suppress the phonon lifetimes, and thus their contributions to κ.
We show the frequency dependent mode Grüneisen parameters derived from third-order anharmonic force constants28 as implemented in Phono3py31 in Fig. 6. We note that mode Grüneisen parameters are independent of crystal direction as well as the scattering rates determined here within the relaxation time approximation. Although the mode Grüneisen parameters vary over a wide range (~−1.0 to 18.0), the average over the whole frequency range is calculated to be 1.46. This is less than the average mode Grüneisen parameter of the acoustic modes of PbTe, PbSe and PbS32 despite the fact that the total thermal conductivity at 300 K is comparable. We note that the Grüneisen parameters of the high frequency modes are similar to or less than the lower frequency acoustic modes. Therefore, as far as anharmonicity is concerned, contributions to κ from optic modes are expected to be similar to or higher than those of acoustic modes with comparable velocities.
Frequency dependent mode Grüneisen parameters and scattering rates derived from third-order anharmonic force constants.
The Grüneisen parameters, however, fail to explain the increase in scattering rates (Fig. 6) and the saturation in the accumulated κ along the a-axis above 3.8 THz (Fig. 2b) despite these branches being significantly dispersive. Given the average mode Grüneisen parameters remain nearly constant in this frequency range and they are independent of crystal direction, one would expect similar scattering rates and significant contributions from the dispersive high frequency branches and further κ anisotropy. This can be explained in terms of the phase space available for three phonon scattering processes in this frequency range as shown in the joint density of states31 in Fig. 7 (see SI for details). The joint density of states is weighted by the Bose-distribution function of the phonon modes involved in the scattering processes at 300 K. The phase space for three-phonon scattering processes increases dramatically for frequencies higher than 3.8 THz, thus the optic phonons in this frequency range have significantly higher scattering rates [Fig. 6], which suppresses their contribution to κ even though the group velocities (and anisotropy) of these modes are significant. Therefore, we conclude that the thermal conductivity anisotropy in h-GST is mainly due to the dispersive optic branches with frequency less than 3.8 THz along the a-axis compared to the flat optic branches with lower group velocities along the c-axis. The differences in optic mode averaged velocities in a material with similar acoustic velocities can be understood in terms of zone folding effects. In particular, the zone folding along the long c-axis leads to more intersections with zone boundaries in this direction. Symmetry requires that non-degenerate modes have zero slopes when touching the boundary, i.e., zero c-direction velocities, but does not impose constraints on the velocities transverse to the boundary. This zone folding effect leads to a material that exhibits thermal anisotropy even though it is mechanically rather isotropic (i.e., the zone center sound velocities are nearly isotropic).
Frequency dependent weighted joint density of states.
Finally, accumulated κ as a function of phonon mean free path (λph) provides insight into heat conduction in nanostructured materials. Figure 8(a) clearly shows that most of the heat is carried by vibrational modes with λph ranging from 1–30 nm in h-GST crystals at 300 K. On the basis of this knowledge, we calculated κ at various temperatures using various grain sizes to examine the nanostructuring effect on κ in this system (Fig. 8b). We find that a reduction of κ as much as 54% can be achieved for grain size of 5 nm. Even for a grain size of 15 nm 31% reduction of κ compared to its bulk counterpart can be achieved. The effect of nanostructuring becomes more prominent at lower temperature where intrinsic λph values become larger. For example, at 200 K, for a grain size of 15 nm, κ drops 65% along a-axis and 63% along c-axis.
(a) Accumulated κ as a function of phonon mean free path. (b) κ as a function of temperature for various grain sizes. The green, blue and magenta curves represent κ for grain sizes of 5 nm, 10 nm and 15 nm, respectively. The dashed and solid lines are for κ along c-axis and a-axis, respectively. The red lines represent bulk κ.
We presented phonon dispersions and thermal conductivity calculations for h-GST. Although h-GST is a relatively isotropic material from a sound velocity perspective, it has a significantly anisotropic thermal conductivity. The reason for this is zone folding due to c-axis layering. This can be regarded as similar to a superlattice phonon scattering mechanism and is reflected in the fact that the anisotropy in the accumulation function starts only in the energy range of the optic branches. This effect is important because the low lying high velocity optic modes contribute significantly to thermal conductivity in h-GST, particularly for the in-plane direction. Intrinsic anisotropy in the thermal conductivity is potentially of interest for devices in cases where the crystalline h-GST phase is used, and the importance of optic phonon contributions to thermal transport may have significant impact on thermoelectric efficiency in materials with complicated phonon dispersions.
Calculations were done with the projector augmented wave (PAW)33,34 method using experimental lattice parameters35 and the Generalized Gradient Approximation (GGA) of Perdew, Burke and Ernzerhof36,37 as implemented in VASP38,39. The internal atomic coordinates were determined by total energy minimization. A 12 × 12 × 4 Monkhorst-Pack grid was used for sampling of the Brillouin zone with an energy cutoff of 550 eV. The convergence threshold for the energy was set to 10−5 eV and 10−3 eV/Å for its gradient. We employed a finite displacement method using the VASP-phonopy40 interface to calculate the harmonic force constants with higher convergence thresholds; 10−8 eV and 10−8 eV/Å for the energy and its gradient, respectively. Born effective charges were calculated using density functional perturbation theory. The third order anharmonic force constants were calculated using VASP-phono3py31 with a 2 × 2 × 2 supercell incorporating interactions out to 5th nearest neighbors. Finally, we calculated thermal conductivity by explicitly solving the phonon Boltzmann transport equation using 12 × 12 × 4 integration meshes. A tetrahedron method was employed for the calculation of the imaginary parts of self-energies. We note that the DFT and κ calculations changed little when increasing integration meshes to 12 × 12 × 8 and 12 × 12 × 12. Details of the method can be found elsewhere31.
Two different crystal structures have been reported for h-GST. We considered the h-GST structures given by Kooi et al.35 and Matsunaga et al.41,42, which differ in Ge-Te stacking. Kooi's structure gives notably lower total energy (0.15 eV) and is therefore likely the correct structure, thus we use this for the κ calculations. We note that while both structures resulted in stable phonon dispersions (no imaginary modes), the lowest order TO(Γ) mode was found to be situated at higher frequency in Matsunaga's structure [See Fig. S1 in the Supplementary Information] compared to Kooi's structure implying sensitivity of the low frequency TO mode to the positions of Ge and Sb.
How to cite this article: Mukhopadhyay, S. et al. Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5. Sci. Rep. 6, 37076; doi: 10.1038/srep37076 (2016).
Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Battaglia, J. L. et al. Thermal characterization of the SiO2-Ge2Sb2Te5 interface from room temperature up to 400 degrees C. J. Appl. Phys. 107, 044314 (2010).
Fallica, R. et al. Thermal and Electrical Characterization of Materials for Phase-Change Memory Cells. J. Chem. Eng. Data 54, 1698–1701 (2009).
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Kim, E. K., Kwun, S. I., Lee, S. M., Seo, H. & Yoon, J. G. Thermal boundary resistance at Ge2Sb2Te5/ZnS: SiO2 interface. Appl. Phys. Lett. 76, 3864–3866 (2000).
Lee, J. et al. Thermal conductivity anisotropy and grain structure in Ge2Sb2Te5 films. J. Appl. Phys. 109, 084902 (2011).
Lyeo, H. K. et al. Thermal conductivity of phase-change material Ge2Sb2Te5. Appl. Phys. Lett. 89, 151904 (2006).
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Siegrist, T. et al. Disorder-induced localization in crystalline phase-change materials. Nat. Mater. 10, 202–208 (2011).
Choi, M., Kim, D. H. & Park, C. H. Microscopic origin of lattice instability in ferroelectric PbTiO3. J. Korean Phys. Soc. 49, S481–S484 (2006).
Suh, D. S. et al. Thermoelectric heating of Ge2Sb2Te5 in phase change memory devices. Appl. Phys. Lett. 96, 123115 (2010).
Lee, J., Kodama, T., Won, Y., Asheghi, M. & Goodson, K. E. Phase purity and the thermoelectric properties of Ge2Sb2Te5 films down to 25 nm thickness. J. Appl. Phys. 112, 014902 (2012).
Sittner, E. R. et al. (GeTe)x-(Sb2Te3)1-x phase-change thin films as potential thermoelectric materials. Phys. Status. Solidi. A 210, 147–152 (2013).
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Slack, G. A. & Oliver, D. W. Thermal Conductivity of Garnets and Phonon Scattering by Rare-Earth Ions. Phys. Rev. B-Solid St. 4, 592 (1971).
Roufosse, M. & Klemens, P. G. Thermal-Conductivity of Complex Dielectric Crystals. Phys. Rev. B 7, 5379–5386 (1973).
Pang, J. W. L. et al. Phonon Lifetime Investigation of Anharmonicity and Thermal Conductivity of UO2 by Neutron Scattering and Theory. Phys. Rev. Lett. 110, 157401 (2013).
Tian, Z. T. et al. Phonon conduction in PbSe, PbTe, and PbTe1-xSex from first-principles calculations. Phys. Rev. B 85, 184303 (2012).
Li, W., Lindsay, L., Broido, D. A., Stewart, D. A. & Mingo, N. Thermal conductivity of bulk and nanowire Mg2SixSn1-x alloys from first principles. Phys. Rev. B 86, 174307 (2012).
Liu, B., Song, Z. T., Zhang, T., Feng, S. L. & Chen, B. M. Raman spectra and XPS studies of phase changes in Ge2Sb2Te5 films. Chinese Phys. 13, 1947–1950 (2004).
Sosso, G. C., Caravati, S., Gatti, C., Assoni, S. & Bernasconi, M. Vibrational properties of hexagonal Ge2Sb2Te5 from first principles. J. Phys-Condens Mat. 21, 254401 (2009).
Tsafack, T., Piccinini, E., Lee, B. S., Pop, E. & Rudan, M. Electronic, optical and thermal properties of the hexagonal and rocksalt-like Ge2Sb2Te5 chalcogenide from first-principle calculations. J. Appl. Phys. 110, 063716 (2011).
Nolas, G. S., Yang, J. & Goldsmid, H. J. Thermal conductivity: theory, properties and applications. 123 (Pelnum, 2004).
Cahill, D. G. et al. Nanoscale thermal transport. J. Appl. Phys. 93, 793–818 (2003).
Chiritescu, C., Mortensen, C., Cahill, D. G., Johnson, D. & Zschack, P. Lower limit to the lattice thermal conductivity of nanostructured Bi2Te3-based materials. J. Appl. Phys. 106, 073503 (2009).
Chen, X. et al. Twisting phonons in complex crystals with quasi-one-dimensional substructures. Nat Commun 6, 6723 (2015).
Wallace, D. C. Thermodynamics of Crystals. (Dover Publications, 1998).
Xu, B. et al. Effects of hydrostatic pressure on the electrical properties of hexagonal Ge2Sb2Te5: Experimental and theoretical approaches. Appl. Phys. Lett. 98, 142112 (2011).
Bies, W. E., Radtke, R. J. & Ehrenreich, H. Phonon dispersion effects and the thermal conductivity reduction in GaAs/AlAs superlattices. J. Appl. Phys. 88, 1498–1503 (2000).
Togo, A., Chaput, L. & Tanaka, I. Distributions of phonon lifetimes in Brillouin zones. Phys. Rev. B 91, 094306 (2015).
Zhang, Y., Ke, X. Z., Chen, C. F., Yang, J. & Kent, P. R. C. Thermodynamic properties of PbTe, PbSe, and PbS: First-principles study. Phys. Rev. B 80, 024304 (2009).
Blochl, P. E. Projector Augmented-Wave Method. Phys. Rev. B 50, 17953–17979 (1994).
Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).
Kooi, B. J. & De Hosson, J. T. M. Electron diffraction and high-resolution transmission electron microscopy of the high temperature crystal structures of GexSb2Te3 + x (x = 1, 2, 3) phase change material. J. Appl. Phys. 92, 3584–3590 (2002).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple (vol 77, pg 3865, 1996). Phys Rev Lett 78, 1396–1396 (1997).
Kresse, G. & Furthmuller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).
Kresse, G. & Furthmuller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comp. Mater. Sci. 6, 15–50 (1996).
Togo, A., Oba, F. & Tanaka, I. First-principles calculations of the ferroelastic transition between rutile-type and CaCl(2)-type SiO(2) at high pressures. Phys. Rev. B 78, 134106 (2008).
Matsunaga, T. et al. Structural investigation of Ge3Sb2Te6, an intermetallic compound in the GeTe-Sb2Te3 homologous series. Appl. Phys. Lett. 90, 161919 (2007).
Matsunaga, T. & Yamada, N. Structural investigation of GeSb2Te4: A high-speed phase-change material. Phys. Rev. B 69, 104111 (2004).
S.M. and L.L. acknowledge support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division and the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. DJS acknowledges support from the Department of Energy through the S3TEC energy frontier research center. S.M. gratefully acknowledges helpful discussions with Prof. Atsushi Togo related to the Phono3Py code.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, 37831, TN, USA
Saikat Mukhopadhyay
& Lucas Lindsay
Department of Physics and Astronomy, University of Missouri, Columbia, 65211-7010, MO, USA
David J. Singh
Search for Saikat Mukhopadhyay in:
Search for Lucas Lindsay in:
Search for David J. Singh in:
S.M. conceived the idea and conducted the calculations. S.M., D.J.S. and L.L. analyzed the results and wrote the manuscript.
Mukhopadhyay, S., Lindsay, L. & Singh, D. Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5. Sci Rep 6, 37076 (2016) doi:10.1038/srep37076
DOI: https://doi.org/10.1038/srep37076
Thermodynamic and thermoelectric properties of CoFeYGe (Y = Ti, Cr) quaternary Heusler alloys: first principle calculations
Raad Haleoot
& Bothina Hamad
Journal of Physics: Condensed Matter (2020)
Atomistic and experimental study on thermal conductivity of bulk and porous cerium dioxide
Linu Malakkal
, Anil Prasad
, Dotun Oladimeji
, Ericmoore Jossou
, Jayangani Ranasinghe
, Barbara Szpunar
, Lukas Bichler
& Jerzy Szpunar
Scientific Reports (2019)
Quasi-two-dimensional GeSbTe compounds as promising thermoelectric materials with anisotropic transport properties
Tian-Ran Wei
, Ping Hu
, Hongyi Chen
, Kunpeng Zhao
, Pengfei Qiu
, Xun Shi
& Lidong Chen
Applied Physics Letters (2019)
Structural, stability and thermoelectric properties for the monoclinic phase of NaSbS2 and NaSbSe2: A theoretical investigation
Mahmoud M. A. Mahmoud
, Daniel P. Joubert
& Mahlaga P. Molepo
The European Physical Journal B (2019)
Lattice Thermal Conductivity of mGeTe•nSb2Te3 Phase-Change Materials: A First-Principles Study
Yuanchun Pan
, Zhen Li
& Zhonglu Guo
Crystals (2019)
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Vote below! Let your voice be heard America!
We all know that while Barack Obama was president he would have given illegal immigrants any and everything for free if he could have. Not only did he stop the deportation of millions of illegals, he made policies that pandered to them.
The video below is the perfect example of how he was willing to sacrifice the good of American Citizens for people who broke our laws and remain in our country illegally.
No! They're not U.S. Citizens.
Yes, they deserve to get a piece of the pie.


Just because you have haemophilia doesn't mean that travelling isn't for you. It just requires a bit more forward planning! And with the right preparation, you should be able to experience the amazing adventures that travel can bring. Here we provide answers to some frequently asked questions that you may find helpful.
Even if you haven't had a bleed for years, being prepared when you travel can help ensure that your trip is memorable for all the right reasons. Perhaps most importantly, you will need to know how to manage your haemophilia independently. Your Haemophilia Treatment Centre should be able to help you with this, so make sure you let them know about your travel plans well in advance.
Depending on whether you are travelling in Australia or overseas, other things you may need to think about include arranging for your Haemophilia Treatment Centre to provide you with a Travel Letter, contacting your airline ahead of time to notify them that you will be bringing your medication and administration kit on board with you, and contacting the consulate of the country where you will be travelling to check if they have any special requirements for carrying medications and administration kits through their border control. If travelling overseas, you should also make sure that you have arranged appropriate health insurance and any necessary vaccinations before you leave.
Treatment for haemophilia varies across the world so the best thing to do is make sure that you bring everything you need to manage your condition with you. You can find a packing list that should help you get ready for your big adventure here. Importantly, you will need to ensure that you take your medication and anything you need to administer an infusion on board the plane with you in the cabin section, so you can ensure that nothing gets lost or damaged. Your Haemophilia Treatment Centre should also be able to help give you tips for packing everything you may need.
How can I transport my medication safely?
It is important that you never pack your clotting factor replacement therapy and administration kits in your checked luggage. This is because the temperature in an airplane's baggage compartment may adversely affect your medication, or it could get lost or damaged. Because it is temperature sensitive, you should take your medication on board with you in a cooler bag. Your Haemophilia Treatment Centre should be able to help you with more information about transporting medication safely.
Do I need travel insurance when travelling overseas?
Travel insurance is an absolute necessity when travelling overseas. As they say, if you can't afford travel insurance, you can't afford to travel! There are a number of companies who provide travel insurance for people with pre-existing conditions such as haemophilia, so shop around to find the policy that best suits your circumstances and travel plans.
It is important to ensure that you declare all pre-existing conditions when applying for travel insurance and you may like to consider adding Evacuation Cover. Before you sign on the dotted line make sure you are clear as to exactly what is covered by your policy so there are no nasty surprises if you need to make a claim. Your Haemophilia Treatment Centre should be able assist you in making all the necessary preparations to help ensure that you have as safe a trip as possible.
Do I need to be able to speak the language of the country that I am visiting?
While it is not necessary to be fluent in the language of the country to which you are travelling, it will be helpful to learn a few key phrases to help manage your treatment while travelling and to ensure that you get the assistance you need in case of an emergency.
Even if you haven't had a bleed for years, being prepared when you travel can help ensure that your trip is memorable for all the right reasons.


When you are new to programming with ASP and are trying to find a superior advent, this can be the booklet for you. built by way of desktop technology professors, Microsoft ASP.NET Programming for absolutely the newbie teaches the rules of programming via uncomplicated online game production. you'll gather the abilities that you just desire for simpler ASP programming purposes and may find out how those abilities may be placed to take advantage of in genuine international situations. better of all, by the point you end this publication, it is possible for you to to use the fundamental rules you might have realized to the following programming language you take on.
This textbook creation to the elemental components of basic astronomy and astrophysics serves as a origin for knowing the constitution, evolution, and saw houses of stars. the 1st 1/2 the ebook explains how stellar motions, distances, luminosities, shades, radii, lots and temperatures are measured or derived.
This is perhaps the most common subtype. In general, you use string variables to store textual values, such as FirstName="William Burroughs" or CityName="Indianapolis". HINT Note in the examples that with string variables you use quotation marks around the value assigned to the variable, but with integer subtypes you do not use quotes. I'll talk more about this difference in the next section. Declaring Constants in VBScript Remember your senior prom or your wedding? Before you walked into the reception hall with your date or spouse, you were announced to the crowd so that everyone would know who you are.
AM FL Y Click Add/Remove Windows 3. The Windows Components Wizard dialog box opens. 3). 4. 4). TE ASP Programming for the Absolute Beginner 6 5. Leave all the options checked for installation. This ensures that you have complete IIS functionality. P TRA When installing IIS, be sure to disable the FTP Server option. Leaving it on can pose some very serious security breaches. 6. Click Install. Note that you might be asked to provide your Windows 2000 CD-ROM to complete the installation process. 3 Note the Description information shown when you click the IIS option.
In a nutshell, server-side processing takes all the guesswork and variability out of utilizing a programming language such as VBScript within your Web pages because the code processing is done on the server, not in the browser. 3 The VBScript in this page allows variables to be assigned values and then allows those values to be displayed. asp is processed on the server, only the resulting HTML is sent to the browser. 4). HINT Untitled-5 30 Because only the resulting HTML is sent to the Web browser, server-side processing is more secure, in general, because a user can't see potentially sensitive program code when viewing the source code.


text:
Q: httpd-devel requires outdated version of glibc-common on CentOS 6.3 httpd-devel requires an outdated version of glibc-common on CentOS 6.3 x86_64 and Apache/2.2.15. It wants 2.12-1.80.el6 and I have 2.12-1.80.el6_3.3.x86_64 installed (via CentOS @update repo)
Here is the error when I run "yum install httpd-devel.x86_64"

Error: Package: glibc-2.12-1.80.el6.i686 (base):

   Requires: glibc-common = 2.12-1.80.el6
   Installed: glibc-common-2.12-1.80.el6_3.3.x86_64 (@updates)
       glibc-common = 2.12-1.80.el6_3.3
   Available: glibc-common-2.12-1.80.el6.x86_64 (base)
       glibc-common = 2.12-1.80.el6

with "yum install httpd-devel.x86_64 --skip-broken", I get:
Packages skipped because of dependency problems:
> apr-1.3.9-3.el6_1.2.i686 from base apr-devel-1.3.9-3.el6_1.2.x86_64
> from base apr-util-devel-1.3.9-3.el6_0.1.x86_64 from base
> cyrus-sasl-devel-2.1.23-13.el6.x86_64 from base
> db4-cxx-4.7.25-17.el6.x86_64 from base db4-devel-4.7.25-17.el6.x86_64
> from base glibc-2.12-1.80.el6.i686 from base
> 1:httpd-devel-2.2.15-15.el6.vm.1.x86_64 from virtualmin
> libuuid-2.17.2-12.7.el6.i686 from base
> nss-softokn-freebl-3.12.9-11.el6.i686 from base
> openldap-devel-2.4.23-26.el6.x86_64 from base

Bottom line, I can't get httpd-devel installed.
Could this be a priority problem?
priority = 1 [asl-3.0]
priority = 1 [base]
priority = 1 [virtualmin]
priority = 1 [virtualmin-universal]
priority = 50 [epel]

repo id | repo name | status
C6.0-base |  CentOS-6.0 - Base | disabled
C6.0-centosplus | CentOS-6.0 - CentOSPlus | disabled
C6.0-contrib | CentOS-6.0 - Contrib |  disabled
C6.0-extras |  CentOS-6.0 - Extras |  disabled
C6.0-updates | CentOS-6.0 - Updates |  disabled
C6.1-base |  CentOS-6.1 - Base | disabled
C6.1-centosplus | CentOS-6.1 - CentOSPlus | disabled
C6.1-contrib | CentOS-6.1 - Contrib |  disabled
C6.1-extras |  CentOS-6.1 - Extras |  disabled
C6.1-updates | CentOS-6.1 - Updates |  disabled
C6.2-base |  CentOS-6.2 - Base | disabled
C6.2-centosplus | CentOS-6.2 - CentOSPlus | disabled
C6.2-contrib | CentOS-6.2 - Contrib |  disabled
C6.2-extras |  CentOS-6.2 - Extras |  disabled
C6.2-updates | CentOS-6.2 - Updates |  disabled
asl-3.0 | Atomicorp - - Atomic Secured Linux 3.0 | enabled: | 623
asl-3.0-testing | Atomicorp - - Atomic Secured Linux 3.0 (TESTING) | disabled
base | CentOS-6 - Base | enabled: | 6,346
c6-media |  CentOS-6 - Media | disabled
centosplus |  CentOS-6 - Plus | disabled
contrib | CentOS-6 - Contrib | disabled
debug | CentOS-6 - Debuginfo |  disabled
epel | Extra Packages for Enterprise Linux 6 - x86_64 |  enabled: 7,627+125
epel-debuginfo | Extra Packages for Enterprise Linux 6 - x86_64 - Debug |  disabled
epel-source |  Extra Packages for Enterprise Linux 6 - x86_64 - Source | disabled
epel-testing | Extra Packages for Enterprise Linux 6 - Testing - x86_64 | disabled
epel-testing-debuginfo | Extra Packages for Enterprise Linux 6 - Testing - x86_64 - Debug | disabled
epel-testing-source |  Extra Packages for Enterprise Linux 6 - Testing - x86_64 - Source | disabled
extras | CentOS-6 - Extras | enabled: |  4
updates | CentOS-6 - Updates | enabled: | 0+523
virtualmin |  RHEL/CentOS/Scientific 6 - x86_64 - Virtualmin |  enabled: | 73
virtualmin-universal | Virtualmin Distribution Neutral Packages | enabled: | 187+1

Apache is from:
rpm -qi httpd
Name        : httpd                        Relocations: (not relocatable)
Version     : 2.2.15                            Vendor: (none)
Release     : 15.el6.vm.1                   Build Date: Thu 17 May 2012 03:35:08 AM UTC
Install Date: Thu 28 Jun 2012 05:13:47 AM UTC      Build Host: srv1.cloud.virtualmin.com
Group       : System Environment/Daemons    Source RPM: httpd-2.2.15-15.el6.vm.1.src.rpm
Size        : 3067984                          License: ASL 2.0
Signature   : DSA/SHA1, Thu 17 May 2012 03:09:42 PM UTC, Key ID e8dd3fa0a0bdbcf9
URL         : http://httpd.apache.org/
Summary     : Apache HTTP Server

A: Disabling priorities allowed "yum install httpd-devel" to work.
PS: i now have priorities as
priority = 10 [asl-3.0]
priority = 10 [asl-3.0-testing]
priority = 20 [virtualmin]
priority = 20 [virtualmin-universal]
priority = 30 [base]
priority = 30 [updates]
priority = 40 [extras]
priority = 50 [epel]

does this seem ok?

A: Congrats:  you have encountered Dependeny Hell [tm].  Good news: It's always self-inflicted; no exceptions.
Virtualmin - I worked with Jamie on a project before outta SCONJ; this isn't like him - is providing an httpd-devel that violates the naming convention set forth by the fedora guidelines that in turn regulates enterprise linux packaging around CentOS as well.  THIS SHOULD NOT HAPPEN -- third-party repositories like Virtualmin should not overload the names of packages delivered upstream (like those in CentOS itself.
So, in short, you were using a bad repo.  Don't feel bad:  a lot of them have this issue, and there's no way to know otherwise.  Evan Dag used to do this in his RPMs.
I've never had to use the priorities setup, and I've been on RedHat/derivs since 98 or so.  I can't comment on whether your solution is valid, and the whole thing seems like a hack to get around a problem that the regs now avoid.
Disable the virtualmin repo.
sed -i '/^enabled/r\enabled=0' /etc/yum.repos.d/name-of-virtualmin.repo-file

Only enable it on the command line for one-off things, and understand until they get it fixed that it will cause dependency issues.
yum --enablerepo virtualmin [command]

Jamie is a VERY smart and capable dev, and his product and repos should be better.  This can only be a short-term thing.

redpajama_set_name: RedPajamaStackExchange


text:
package org.apache.felix.dm.lambda.samples.compositefactory;

/**
 * Our properties interface that is implemented by DependencyManager.
 * @author Felix Project Team
 */
public interface MyConfig {
    String getFoo();
}

redpajama_set_name: RedPajamaGithub


INDEPENDENT LEGAL ADVICE OR "ILA" IN A SEPARATION AGREEMENT – IS THERE A DIFFERENCE?
Firstly, Happy New Year! Today's topic is: "Independent Legal Advice," commonly referred to as "ILA." Following are four scenarios which in my view illustrate the common assumptions and mis-assumptions of what ILA means and the huge importance that it has.
I'll use the words "Independent Legal Advice" to mean that each party retains his/her own lawyer to advise them in the negotiation of a Separation Agreement or Marriage Contract ("Pre-nup"). I'll use the shortened "ILA" to mean that a party wants "quick and cheap" advice from a lawyer and the lawyer's signature on the "Certificate of Independent Legal Advice" attached to the Agreement. Is there a difference? The following 4 scenarios* I hope will provide the answer.
Is there a difference? The following 4 scenarios I hope will provide the answer.


text:
< Previous | Prasoon Joshi
Prakash Jha | Next >
Prashant Ruia
The New-Age Entrepreneur
When you're a young boy born into one of India's most wealthy business families, you can be forgiven for living it up as a teenager.
Instead, Prashant Ruia showed up at the offices of his family corporation, Essar, at age 15. "In 1985, it was an exciting time for the company — we were just getting going, and I just wanted to get on with it," he told UK's The Telegraph. It often seems like he hasn't stopped since.
Now Chief Executive of the Essar Group, a multinational conglomerate with interests in shipping, power, steel, oil and gas, communications and ports, Prashant is that rarest of combinations: a strategic thinker who's also good at execution and operations. That explains why Essar today employs over 75,000 people and operates in over 25 countries.Prashant has been instrumental in taking the company beyond its traditional strengths: he helped orchestrate the Essar-Vodafone partnership, to give Essar a key role in India's mobile telephony revolution; he also helped combine Essar's oil and gas businesses under the umbrella of Essar Energy to make it India's second largest private power producer.
Last year, he set his sights on listing Essar Energy, an FTSE 100 company, on the London Stock Exchange — a milestone the group achieved in May 2010.
< Previous | Prasoon Joshi /


text:
Xiaojue Wang
Graduate Program Director
Degree: B.A., MA., Peking; M.Phil., Ph.D., Columbia
Specialty: Modern and contemporary Chinese and Sinophone literature; the cultural Cold War; Chinese-German intellectual connections; cultural memories; film and media studies; gender and sexuality
326 Scott Hall
Xiaojue Wang is Associate Professor of Chinese Literature in the Department of Asian Languages and Cultures and Director of Graduate Studies in the Program in Comparative Literature. Her research interests are Chinese literature and culture from late imperial to contemporary periods, cultural Cold War studies in global Asias, Chinese-German intellectual connections, cultural memories, film and media studies, gender and sexuality, and comparative literature. She is the author of Modernity with a Cold War Face: Reimagining the Nation in Chinese Literature across the 1949 Divide (Harvard University Asia Center, 2013), which examines the diverse, dynamic cultural practices in mainland China, Taiwan, Hong Kong, and overseas across the 1949 Chinese divide, and re-positions modern Chinese literature in the global context of the Cold War.
Professor Wang is currently completing her second book, tentatively entitled The Edges of Literature: Eileen Chang and the Aesthetics of Deviation, which seeks to chart the Cold War cultural geography in the transpacific and global Asias. Centering on the prominent bilingual woman writer Eileen Chang, this study explores how Chang maneuvered between art and politics; colonialism, modernization, and cosmopolitanism; migration and expatriation; as well as high art, popular culture, and technology.
Her work has appeared in Verge: Studies in Global Asias, Interventions: International Journal of Postcolonial Studies, CLCWeb: Comparative Literature and Culture, Chinese Literature: Essays, Articles, Reviews (CLEAR), and MCLC Modern Chinese Literature and Culture, and numerous Chinese-language journals including Twenty-First Century, Modern Chinese Literature Studies, Dushu, Foreign Literature Review, etc. She is also the Chinese translator or co-translator of Jürgen Habermas' Strukturwandel der Öffentlichkeit, Horkheimer Reader, Andreas Huyssen's After the Great Divide: Modernism, Mass Culture, Postmodernism, and John Fiske's Understanding Popular Culture, among others.


text:
Yoon, Choi, and Yun: Detecting Bacterial Growth in Continuous Ambulatory Peritoneal Dialysis Effluent Using Two Culture Methods
The Korean Journal of Internal Medicine 2010;25(1):82-85.
Detecting Bacterial Growth in Continuous Ambulatory Peritoneal Dialysis Effluent Using Two Culture Methods
Se-Hee Yoon, Nak Won Choi, Sung-Ro Yun
Department of Internal Medicine, Konyang University College of Medicine, Daejeon, Korea.
Correspondence to Se-Hee Yoon, M.D. Department of Internal Medicine, Konyang University College of Medicine, 685 Gasuwon-dong, Seo-gu, Daejeon 302-718, Korea. Tel: 82-42-600-9066, Fax: 82-42-600-9090, sehei@hanmail.net
Received April 24, 2009 Accepted August 03, 2009
The aim of this study was to evaluate the peritonitis-causing bacteria detected in peritoneal fluid using a blood culture bottle in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).
One-hundred and eleven dialysates from 43 patients suspected of peritonitis related to CAPD were retrospectively evaluated between May 2000 and February 2008. In all cases, 5 to 10 mL of dialysate was inoculated into a pair of BacT/Alert blood culture bottles, and 50 mL of centrifuged dialysate was simultaneously inoculated into a solid culture media for conventional culture. The results were compared to those of the conventional culture method. Isolated microorganisms were compared between the two methods.
The blood culture method was positive in 78.6% (88 / 112) of dialysate specimens and the conventional culture method in 50% (56 / 112, p < 0.001).
The blood culture method using the BacT/Alert system is useful for culturing dialysates and improves the positive culture rate in patients with suspected peritonitis compared to the conventional culture method.
Keywords: Culture media; Peritoneal dialysis; Peritonitis; Sensitivity and specificity
Continuous ambulatory peritoneal dialysis (CAPD) is an important form of dialysis treatment for patients with end-stage renal disease as compared to hemodialysis. The major complication of CAPD is peritonitis, which accounts for significant antibiotic use in patients undergoing peritoneal dialysis. According to the International Society for Peritoneal Dialysis (ISPD) and the contemporary treatment guidelines [1-3], antibiotic therapy should be adjusted based on the Gram stain or culture results after empiric initial therapy for peritoneal dialysis-related peritonitis. Prolonged and unnecessary broad antibiotic exposure poses serious concerns due to the significant potential for inducing and selecting resistance, as well as for susceptibility to antibiotic toxicities and fungal peritonitis. Therefore, a definitive microbiological diagnosis and an appropriate adjustment to therapy are important [4].
According to the current ISPD guidelines, the centrifuged sediment of peritoneal effluent is recommended to be inoculated on both solid culture media and blood culture (BC) medium, and if equipment for centrifuging large volumes of fluid is not available, BC bottles can be directly infected with 5 to 10 mL of effluent [2]. Many reports support the advantage of the BC method over the conventional culture (CC) method [5-12]. However, the CC method is still used as the priority method for isolating bacteria in CAPD peritonitis in many hospitals.
The aim of this study was to determine how effective the BC method is for culturing CAPD effluent compared to the current method of culturing concentrated CAPD effluent in solid media.
The dialysates of patients suspected of having CAPD peritonitis based on clinical signs and symptoms (abdominal pain with or without fever and peritoneal signs and/or cloudy fluid) between May 2000 and February 2008 were included in this study. We reviewed all of the peritonitis cases during the study period and excluded cases that were not cultured simultaneously by both the BC and CC methods. Specimens were aseptically obtained from the drained effluent bag. Dialysate (5 to 10 mL) was inoculated into one aerobic and one anaerobic BacT/Alert BC bottle at bedside and transported to the microbiology laboratory. Additionally, 50 mL of dialysate was transported to the laboratory in a sterile container. The 50 mL of dialysate was centrifuged at 3,000 g for 15 minutes, and the sediment was used for the CC method. The CC method included inoculating the centrifuged sediment onto 5% sheep's blood, MacConkey agar, and thioglycollated broth, which were incubated at 35℃. The plates were examined after 24 and 48 hours, and the broth was kept for 5 days and examined for growth daily. The isolated organisms were identified and susceptibility testing was performed using the VITEK test card (BioMerieux Vitek, Inc., Hazelwood, MO, USA). The BC method was performed using 5 - 10 mL of peritoneal dialysis effluent inoculated into aerobic and anaerobic BacT/Alert bottles (Organon Teknika Inc., Scarborough, Ontario, Canada), following the manufacturer's instructions. Both bottles were then incubated in the BacT/Alert system at 36℃ with continuous agitation and monitoring for 5 days. The broth was aspirated for Gram staining when bacterial growth was detected by CO2 production. The broth was then subcultured on 5% sheep's blood and chocolate agars and incubated at 35℃ in 5% CO2 for 2 days. The resulting bacteria were identified by the VITEK test card.
The statistical analysis was performed with SPSS for Windows version 10 (SPSS Inc., Chicago, IL, USA). The final reporting statistical comparisons were performed using the paired Student's t-test, and comparisons of the percentages between groups were made with the McNemar test. The level of significance was 0.05.
Organisms from the 112 episodes of peritonitis were isolated using both the BacT/Alert BC bottle method and the conventional centrifugation culture method from May 2000 to February 2008. All cases met the diagnostic criteria for peritonitis. None of the patients were on antibiotics at the time of specimen collection.
Characteristics of isolated bacteria from CAPD fluid
The microbiological characteristics of the peritonitis episodes are listed in Table 1. Using both the BC and CC methods, 81.2% positive cultures were detected. In this series, Gram-positive bacteria were predominant in patients over Gram-negative bacteria (56.3% and 21.4%, respectively). The most common Gram-positive organism was coagulase-negative Staphylococcus, which was detected in 30 of the peritonitis cases (26.8%). Others were Streptococcus species in 19 of the cases (17.0%), Staphylococcus aureus in six (17%), and Corynebacterium species in five (4.5%). The most common Gram-negative organisms were Escherichia coli and Acinetobacter species, which were detected in five cases each (4.5%), and others were Stenotrophomonas species in four cases (3.6%) and Enterobacter in three (2.7%) (Table 1).
Positive rates using the two culture methods
The BC method detected 88/122 (78.6%) positive cultures and the CC method detected 56/112 (50%) (p < 0.0001). The Gram-positive bacteria positive rate was 58.9% (66 / 112) using the BC method and 32.1% (36 / 112) using the CC method (p < 0.0001). The Gram-negative bacteria positive rate was 20.5% (23 / 112) for the BC method and 15.2% (17 / 112) for the CC method (p = 0.07). Of the 112 patients, results from 53 (47.3%) agreed for both methods, whereas 1 / 112 (0.9%) partially agreed. In this case, Streptococcus was isolated using both methods and Pseudomonas was isolated by the BC method only. Thirty-four percent (38 / 112) of the bacterial species were isolated with the BC method only, and the majority were Gram-positive bacteria such as Streptococcus species (12 / 112) and coagulase-negative Staphylococcus (11 / 112), while five (5 / 112) Gram-negative bacterial species were isolated with the CC method group. Yeast, Enterococcus, Streptococcus, and coagulase-negative Staphylococcus were cultured only by the CC method (Table 2).
This study showed that microbiological culture rates improved significantly using the BC rather than the CC method. The sensitivities of the BC method and the CC method were 78.6% and 50%, respectively. The range of organisms detected was similar to those reported in previous studies, with Gram-positive organisms dominating (61 / 112, 54.5%). In 1982, Kammerer et al. [5] introduced the BC method to diagnose CAPD peritonitis. In the same year, Luce et al. [6] showed that the incidence of culture negative peritonitis could be reduced from 22% to 4% using the BC method. Since then, many other studies have supported these results [7,8].
Several other methods have been used to improve the sensitivity of culturing dialysates. These methods include centrifugation, filtration, enrichment procedures, large-volume culture, and phagocytic cell lysis. However, some of these methods are time-consuming and require considerable specimen manipulation [9-12]. The advantages of the BC method using the BacT/Alert system include noninvasive monitoring, earlier detection of microbial growth, and decreased technologist manipulation [13].
Several studies have reported on using the BC culturing method for patients with spontaneous bacterial peritonitis, but published data on its use for culturing dialysate from patients with CAPD peritonitis are lacking in Korea [14-17].
Several possible explanations exist for the advantages of the BC method. The sodium polyanethol sulfonate present in the BC bottles acts as an anticoagulant and provides antiphagocytic activity to the culture medium, which may be significant [18]. The direct inoculation of dialysate in the BC method may also reduce the bacterial death and contamination rate. In the CC method, bacteria may die because of delayed inoculation and the continued endogenous antimicrobial activity of the ascetic fluid. Another advantage of the BC method is the reduced time to initially detect a positive culture because the BC bottles are continuously monitored by the BacT/Alert instrument. The BacT/Alert system is a continuous monitoring blood culture system that uses colorimetry to detect CO2 production.
The difference in the Gram-negative organism detection rates for the BC and CC methods was not significant (p = 0.070). However, the total number of Gram-negative organisms was low (24), and 23 Gram-negative organisms were detected by the BC method. Only one Gram-negative organism was missed by the BC method, whereas seven Gram-negative organisms were missed by the CC method.
In this study, the BC method failed to identify yeast. One study reported that the BacT/Alert system failed to detect a significant number of fungemia episodes with the use of BC bottles [19]. This may have been due either to a failure of the medium to support the growth of such fungi or the failure of the computer-generated algorithms of the instrument to detect such growth even when it was present [20].
We use the simple dialysate effluent for the BC media rather than the centrifuged effluent because using centrifuged effluent is a complicated procedure and because of the limitations of a retrospective study.
In summary, although it may have limitations for fungus detection, the direct inoculation of peritoneal fluid into a BC bottle improves the positive culture rate in patients with suspected peritonitis compared to the CC method. Thus, the BC method allows for an earlier appropriate antibiotic treatment and reduces unnecessary antibiotic toxicity.
1. Keane WF, Alexander SR, Bailie GR, et al. Peritoneal dialysis-related peritonitis treatment recommendations: 1996 update. Perit Dial Int 1996;16:557–573PMID : 8981523.
2. Piraino B, Bailie GR, Bernardini J, et al. Peritoneal dialysis-related infections recommendations: 2005 update. Perit Dial Int 2005;25:107–131PMID : 15796137.
3. Caring for Australians with Renal Impairment (CARI). The CARI guidelines. Evidence for peritonitis treatment and prophylaxis: treatment of peritoneal dialysis-associated peritonitis in adults. Nephrology (Carlton) 2004;9(Suppl 3):S91–S106PMID : 15469568.
4. Troidle L, Gorban-Brennan N, Kliger A, Finkelstein FO. Continuous peritoneal dialysis-associated peritonitis: a review and current concepts. Semin Dial 2003;16:428–437PMID : 14629601.
5. Kammerer J, Dupeyron C, Vuillemin N, Leluan G, Fouet P. Importance of cytologic and bacteriologic examination of ascitic fluid from cirrhotic patients in the diagnosis of bacterial peritonitis: apropos of 610 samples from 156 patients. Med Chir Dig 1982;11:243–251PMID : 7109757.
6. Luce E, Nakagawa D, Lovell J, Davis J, Stinebaugh BJ, Suki WN. Improvement in the bacteriologic diagnosis of peritonitis with the use of blood culture media. Trans Am Soc Artif Intern Organs 1982;28:259–262PMID : 6761935.
7. Lye WC, Wong PL, Leong SO, Lee EJ. Isolation of organisms in CAPD peritonitis: a comparison of two techniques. Adv Perit Dial 1994;10:166–168PMID : 7999819.
8. Rayner BL, Williams DS, Oliver S. Inoculation of peritoneal dialysate fluid into blood culture bottles improves culture rates. S Afr Med J 1993;83:42–43PMID : 8424203.
9. Males BM, Walshe JJ, Garringer L, Koscinski D, Amsterdam D. Addi-Chek filtration, BACTEC, and 10-ml culture methods for recovery of microorganisms from dialysis effluent during episodes of peritonitis. J Clin Microbiol 1986;23:350–353PMID : 3517053.
10. Doyle PW, Crichton EP, Mathias RG, Werb R. Clinical and microbiological evaluation of four culture methods for the diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis. J Clin Microbiol 1989;27:1206–1209PMID : 2753997.
11. Sewell DL, Golper TA, Hulman PB, et al. Comparison of large volume culture to other methods for isolation of microorganisms from dialysate. Perit Dial Int 1990;10:49–52PMID : 2128189.
12. Taylor PC. Routine laboratory diagnosis of continuous ambulatory peritoneal dialysis peritonitis using centrifugation/lysis and saponin-containing media. Eur J Clin Microbiol Infect Dis 1994;13:249–252PMID : 8050439.
13. Weinstein MP, Mirrett S, Reimer LG, et al. Controlled evaluation of BacT/Alert standard aerobic and FAN aerobic blood culture bottles for detection of bacteremia and fungemia. J Clin Microbiol 1995;33:978–981PMID : 7790471.
14. Alfa MJ, Degagne P, Olson N, Harding GK. Improved detection of bacterial growth in continuous ambulatory peritoneal dialysis effluent by use of BacT/Alert FAN bottles. J Clin Microbiol 1997;35:862–866PMID : 9157143.
15. Vas SI, Law L. Microbiological diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis. J Clin Microbiol 1985;21:522–523PMID : 3886688.
16. Runyon BA, Umland ET, Merlin T. Inoculation of blood culture bottles with ascitic fluid: improved detection of spontaneous bacterial peritonitis. Arch Intern Med 1987;147:73–75PMID : 3541825.
17. Runyon BA, Hoefs JC. Culture-negative-neutrocytic ascites: a variant of spontaneous bacterial peritonitis. Hepatology 1984;4:1209–1211PMID : 6500513.
18. Ludlam HA, Price TN, Berry AJ, Phillips I. Laboratory diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis. J Clin Microbiol 1988;26:1757–1762PMID : 3183023.
19. Lyon R, Woods G. Comparison of the BacT/Alert and Isolator blood culture systems for recovery fungi. Am J Clin Pathol 1995;103:660–662PMID : 7741115.
20. Khare S, Yurack J, Toye B. Culture of dialysate in suspected CAPD associated peritonitis using the BacT/Alert system. Diagn Microbiol Infect Dis 1996;25:101–106PMID : 8902403.
Characteristics of causative organisms isolated from 112 peritonitis
Values are presented as number (%).
Comparison of microorganism recovery from peritoneal fluid between the two culture methods (n = 112)
Pleural and pericardial empyema in a patient with continuous ambulatory peritoneal dialysis peritonitis 2013 September;28(5)
Mycobacterium fortuitum Peritonitis Associated with Continuous Ambulatory Peritoneal Dialysis 1993 January;8(1)
Eosinophilic Peritonitis in a Patient with Continuous Ambulatory Peritoneal Dialysis CAPD 2004 June;19(2)
Relationship between the Serum Parathyroid Hormone and Magnesium Levels in Continuous Ambulatory Peritoneal Dialysis CAPD Patients using Low - magnesium Peritoneal Dialysate 2002 June;17(2)


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Тигар ајкула  (Galeocerdo cuvier) врста је ајкуле и део породице Galeocerdo. Ова врста велики је макропредатор, а може да достигне дужину преко 5 м.  Живи у тропским и умерено тропским водама, посебно око централних острва Пацифика. Име је добила због тамних пруга које подсећају на тигрове, али како сазрева оне бледе. Углавном лову ноћу и сама, а храни се са великим бројем живих организама, укључујући морске псе, ракове, рибе, туљане, корњаче, морске змије, делфине па чак и друге мање ајкуле.

Због своје разноврсне исхране названа је "предатором смећа", а и зато јер конзумира и неке нејестиве предмете, који су јој пронађени у стомаку. Сматра се скоро угроженом врстом, а лови се углавном због пераја. Тиграста ајкула је друга по реду ајкула која највише напада људе.

Таксономија и опис

Тигар ајкулу су први описали биолози Перон и Лесур 1882. године и назвали је Squalus cuvier. Милер и Хенле су 1837. године ову врсту преименовали у Galeocerdo tigrinus. Род Galeocerdo потиче од грчке речи galeos што значи морски пас, а kerdo значи лисица. Често се ова врста колоквијално назива морски пас ајкула. Ова врста члан је реда Carcharhiniformes у којој се налази још 270 врста. Припаднике ове врсте карактеришу мембране на очима, два леђна пераја, анална пераја и пет шркржних прореза. Највећи члан ове породице је Carcharhinidae.

Тигар ајкула обично достиже дужину од 3,25 до 4,25 м и тешка је од 385 до 635 килограма. Женке ове врсте су изузетно крупне и прелазе дужину од 5 м, док су највећи мужјаци дужине до 4 м.  Поједини примерци су тежине и до 900 килограма. У водама Аустралије рибари су ухватили трудну женку ајкуле, која је имала 5,5 м, а тежила је 1524 килограма. У старим студијама пописана је ајкула ове врсте дужине од 7,4 м, али она нија научно потврђена. Тигаг ајкула друга је највећа врста у својој породици иза врсте Rhincodon typus. Зуби тигар ајкуле су врло оштри и изражени, оформљени тако да се пробијају кроз месо и кости жртве, а могу да сломе оклоп корњаче или шкољку. Током живота неколико пута мењају зубе, а друге врсте из исте породице имају доста краће зубе од тигар ајкуле. Зуби су широки готово колико и њихов корен, велики и бели.

Тиграста ајкула има дугачко пераје и дугачки реп, због којег је у могућности да се брзо креће. Ова врста обично користи мале покрете тела како би пливала. Имају висока леђна пераја. Кожа ове врсте креће се од плаве до светлозелене са белим или светложутим мрљама. Предност овога у томе што када лови плен може бити камуфлирана. Тамне мрље и пруге највидљивије су код младих примерака тигар ајкуле.

Глава им је у облику клина што олакшава окретање на једну страну. На њушци имају мале бразде који садрже електрорецепторе што им омогућава да лакше дођу до хране. Тигар ајкуле такође имају сензорни орган звани "бочна линија" који се протеже на бочним странама тела, а примарна структура овог органа је откривање вибрација у води односно помоћ у лову и откривању плена. Иако врсте из њене породице немају доњи капак, тигар ајкула има мембрану која може да покрије око. Рефлентивни слој иза мрежнице тиграсте ајкуле омогућава ћелијама да виде и у условима слабог осветљења.

Станиште и исхрана

Тигар ајкула се често креће уз обалу, углавном у тропским и суптропским водама широм света. Њено понашање је првенствено номадско, али је  вођена топлим струјама и остаје ближе Екватору током хладнијих месеци. Има тенденцију да се задржава у дубоким водама уз гребене. У западном делу Тихом океана такође је пописана ова врста, као и у водама Јапана и Новог Зеланда. Забележена је и на Медитерану, у водама око Шпаније и Сицилије. Тигар ајкуле такође настањују Мексички залив, као и воде Северне Америке. Остале локације где су пописане укључују Африку, Кину, Индију, Аустралију и Индонезију. Појединци из ове врсте лоцирани су на дубинама од 900 м, док су у водама око Хаваја примећени на дубинама од само 3,5 м и редовни су у приобалним водама дубине од 6 до 12 м.

Тиграста ајкула храни са великим бројем рибљих врста и другим водоземцима. Ове грбљивице углавном једу ноћу, а откривено је да се млади примерци углавном хране ситним рибама, медузама и мекушцима, као и главоношцима.

Отприлике у време када достигну дужину од 2,3 односно буду близу сексуално зрелости, њихов избор хране знатно се проширује и почињу да лове много веће рибе. Хране се великим бројем риба, раковима, морским змијама, делфинима (дугонг), перајарима, морским лавовима, морским корњачама, џиновским кожастим корњачама, Caretta caretta, зеленим морским корњачама и мањим врстама тигар ајкула. У чак 28,8% примерака на којима се истраживало пронађене су морске коњаче, што указује да се њима доста често хране. Због великог ризика, делфини често избегавају регије у којима живе тигар ајкуле. Документовано је како ова врста у групи напада болесног грбавог кита 2006. године близу Хаваја. Тигар ајкула се храни и мртвим китовима, што је такође документовано.

Исхрана и размножавање

Поред одличног вида и јаких зуба, ова ајкула преузима велики део плена у водама које настањује и има мало природних непријатеља. Има могућност да хвата таласе ниских фреквенција и тако прати свој плен чак и у мутној води. У стомацима неколико тигар ајкула пронађени су и коњи, козе, овце, пси, мачке, пацови, у водама око Хаваја. Због свог агресивног понашања и неселективног стила храњењна, тигар ајкула често једе нејестиве предмете попут лименки, гума и других.  Све тигар ајкуле пливају споро, што може отежати њихову потрагу за пленом. Међутим, добро се камуфлирају и упрокос томе што су споре, једне су од бољих пливача у својој породици.

Мужјаци тигар ајкуле достижу сексуалну зрелост када буду од 2,3 до 2,9 м дужине, а женке када буду 29, до 3,5 м. Типична тежина младих и сексуално зрелих примерака тигар ајкуле је од 80 до 130 кг. Женке се паре једном у три године, а размножавају се унутрашњом оплодњом. Парење се у северној хемисфери одвија између марта и маја, а женка се порађа између априла и јуна наредне године. На јужној хемисфери парење се одбија у новембру, децембру или почетком јануара. Млади се рађају као потпуно развијени, а развијају се у мајчином телу до 16 месеци. Легла се крећу од 10 до 80 младунаца, новорођенче је дугачко између 51 и 76 цм. Није познат животни век тигар ајкуле, али се зна да живе дуже од 12 година.

Тигар ајкула редовно се лови због пераја, меса или јетре у некомерцијалном риболову. Због сталне потражње за њеним перајем, може се довести до тога да она постане угроженија. Врста се сматра скоро угроженом због риболова, према подацима Међународне уније за заштиту природе. У јуну 2018. године, Министарство за заштиту животне средине Новог Зеланда квалификовало је ову врсту као сигурну и неугрожену. Пераје ове врсте има врло мало храњивих састојака, а јетра има високу концетрацију витамина А, који се користи у производњи витаминских уља. Поред тога, тигар ајкула се лови због своје коже и велике килаже. Иако ове врсте ретко нападају људе, наводи се да је тигар ајкула одговорна за велики део инцидената и сматра се најопаснијом од свих ајкула.

Често посећује гребене, луке и канале, па је често у близини људи. Такође настањује ушћа неких река и мањим потоцима који се уливају у океане. Заузима друго место по броју напада на људе, одмах иза велике беле ајкуле. Између 1959. и 2000. године убијено је 4688 тигар ајкула како би се сачувао туризам широм света. Упркос оштећењу популације, показало се да се њен број није драстично смањио, а данас је лов на њу забрањен на Хавајима и у другим државама света.

Галерија

Референце

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 Ross DA (2000) The Fisherman's Ocean Stackpole Books.

 Simmonds EJ and MacLennan, DN (2005) Fisheries Acoustics Blackwell Publishing.

Спољашње везе

 General information Enchanted Learning. Retrieved January 22, 2005.
 "Different diet information" Shark Info. Retrieved January 22, 2005.
 "Tiger sharks in Hawaii" Research program. Retrieved January 22, 2005.
 "Tiger shark: Fact File" from National Geographic
 Tracking research on tiger sharks
 Pictures of tiger sharks
 Diver Has Been Friends With Tiger Shark For 20 Years!

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