Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid large reabsorption losses. However, determination of the optimum Tm(3+) concentration required to ensure efficient energy transfer from Cr(3+) to Tm(3+) and from Tm(3+) to Ho(3+) has not been made in the Ho:Tm:CR:YAG crystal. The results obtained so far are given

Posterior mini-incision total hip arthroplasty controls the extent of post-operative formation of heterotopic ossification.

Heterotopic ossification (HO) is the formation of bone at extra-skeletal sites. Reported rates of HO after hip arthroplasty range from 8 to 90 %; however, it is only severe cases that cause problems clinically, such as joint stiffness. The effects of surgical-related controllable intra-operative risk factors for the formation of HO were investigated. Data examined included gender, age of patient, fat depth, length of operation, incision length, prosthetic fixation method, the use of pulsed lavage and canal brush, and component size and material. All cases were performed by the same surgeon using the posterior approach. A total of 510 cases of hip arthroplasty were included, with an overall rate of HO of 10.2 %. Longer-lasting operations resulted in higher grades of HO (p = 0.047). Incisions >10 cm resulted in more widespread HO formation (p = 0.021). No further correlations were seen between HO formation and fat depth, blood loss, instrumentation, fixation methods or prosthesis material. The mini-incision approach is comparable to the standard approach in the aetiology of HO formation, and whilst the rate of HO may not be controllable, a posterior mini-incision approach can limit its extent

HUBUNGAN ANTARA KESEIMBANGAN, KELINCAHAN DAN KOORDINASI MATA-KAKI DENGAN DRIBBLING DI SSB KECAMATAN KATAPANG

Tujuan dalam penelitian ini adalah untuk menelaah mengenai hubungan antara keseimbangan, kelincahan dan koordinasi mata-kaki dengan dribbling di ssb kecamatan katapang. Sampel diambil sebanyak 15 orang yang berada di SSB DOMESTIK Kec Katapang dengan menggunakan teknik purposive sampling. Pengambilan data dilakukan melalui tes Keseimbangan, Kelincahan dan Koordinasi mata-kaki terhadap dribling. Perhitungan statistik menggunakan SPSS dengan pearsoncorelation . Dari hasil pengolahan dan analisis data diperoleh hasil nilai pearson correlation tes keseimbangan dengan nilat r = -0,818. p = 0.000< 0.05 maka Ho ditolak. Tes kelincahan dengan r = 0.687. p = 0.005< 0.05 maka Ho ditolak. Tes koordinasi mata-kaki terhadap Dribling dengan diatas nilai r = 0,598, p = 0,019< 0,05 maka Ho ditolak,hubungan kelincahan, keseimbangan dan koordinasi mata kaki terhadap dribbling dengan nilat r = 0,917. p = 0.000< 0.05 maka Ho ditolak. Maka peneliti dapat menyimpulkan terdapat hubungan yang signifikan antara Kelincahan , Keseimbangan dan Koordinasi mata-kaki terhadap kemampuan Dribbling di SSB kecamatan Katapang. ----------- The Relationship Among Balance, Agility, and Ankle Coordination in Dribbling at SSB Katapang Distric

Rare earth elements in Andaman Island surface water : geochemical tracers for the monsoon

The Asian summer monsoon affects the lives of billions of people. With the aim of identifying geochemical tracers for the monsoon related freshwater input from the major rivers draining into the Bay of Bengal and Andaman Sea we have taken surface seawater samples from various locations up and down the Andaman Islands during 2011. Importantly, in some locations samples have been taken in March, July and November, covering most of a seasonal cycle and different monsoon phases. Samples were collected from the side of small wooden boats or while swimming and were filtered within a few hours at 0.45 or 0.22 microns using the vacuum produced by a water jet or a hand operated peristaltic pump. Filtered and unfiltered samples were acidified to < pH 2 and analysed for Y and the REEs with an automated online preconcentration ICP-MS technique [1]. The local input of REEs from streams and sediment rich areas such as mangrove environments is clearly identified by middle REE enrichments in the shale normalised patterns of some samples. These middle REE bulges accompany large increases in dissolved REE concentrations at some locations, especially for the July samples obtained during the peak monsoon season with frequent storms. Y/Ho fractionation aslo occurs during the local input of dissolved REEs with affected samples having lower Y/Ho ratios. Conversly, some samples, in particular those taken after heavy rainfall in March, show strong REE scavenging accompanied by the prefferential removal of dissolved light REEs and higher Y/Ho ratios. The time series at a location away from local input sources shows remarkably similar REE patterns and concentraions in March and July. Then in October-November, following the peak in monsoon river discharge, the dissolved REE concentration increases by almost a factor of 2. The notable exception to this seasonal pattern is the Ce anomally which is around 0.3 in March and November but 0.6 in July, implying less oxidative removal of Ce(IV) during the peak summer monsoon rains. With the exception of elevated dissolved Ce concentrations, the North Pacific Deep Water normalised REE patterns are similar to those reported for offshore samples from the Bay of Bengal and Andaman Sea [2]. These seawater normalised patterns are distinctive having a middle REE enriched arc with similar light and heavy REE values suggesting the input from large rivers in the region is traceable using seawater REE chemistry. [1] Hathorne et al. (2012), Online preconcentration ICP-MS analysis of rare earth elements in seawater, Geochem. Geophys. Geosyst., 13, Q01020, doi:10.1029/2011GC003907. [2] Amakawa et al. (2000), Geochim. Cosmochim. Acta 64, 1715-1727

An Inframarginal Analysis of the Heckscher-Olin Model with Transaction Costs and Technological Comparative Advantage

In the paper we introduce technological comparative advantage and transaction costs into the Heckscher-Olin (HO) model and refine the HO theorem, the Stolper-Samuelson theorem, the Rybczynski theorem, and factor equalization theorem. The refined core theorems can be used to accommodate recent empirical evidence that is at odds with the core theorems.H-O theorem, factor equalization theorem, Stolper-Samuelson theorem, Rybczynski theorem

The Determinants of Immigration-Policy Preferences in Advanced Economies: A Cross-Country Study

This paper employs survey data to examine the determinants of immigration-policy preferences among ten advanced economies. Ordered probit specifications suggest that skill level is a robust determinant of immigration-policy preferences and that less-skilled workers are more likely to express a preference for policies that restrict immigration. The results also suggest that older individuals, members of trade unions, and those who classify their political ideology as conservative are more likely to favor limiting immigration while non-citizens are less likely to favor such policies. Individual country-level regression results vary, in particular with regard to the influence of trade union member- ship, which is a robust determinant of immigration-policy preferences for both measures of skill in only a subset of nations. (JEL FO, F2, HO