Multirelational Organization of Large-scale Social Networks in an Online World

The capacity to collect fingerprints of individuals in online media has revolutionized the way researchers explore human society. Social systems can be seen as a non-linear superposition of a multitude of complex social networks, where nodes represent individuals and links capture a variety of different social relations. Much emphasis has been put on the network topology of social interactions, however, the multi-dimensional nature of these interactions has largely been ignored in empirical studies, mostly because of lack of data. Here, for the first time, we analyze a complete, multi-relational, large social network of a society consisting of the 300,000 odd players of a massive multiplayer online game. We extract networks of six different types of one-to-one interactions between the players. Three of them carry a positive connotation (friendship, communication, trade), three a negative (enmity, armed aggression, punishment). We first analyze these types of networks as separate entities and find that negative interactions differ from positive interactions by their lower reciprocity, weaker clustering and fatter-tail degree distribution. We then proceed to explore how the inter-dependence of different network types determines the organization of the social system. In particular we study correlations and overlap between different types of links and demonstrate the tendency of individuals to play different roles in different networks. As a demonstration of the power of the approach we present the first empirical large-scale verification of the long-standing structural balance theory, by focusing on the specific multiplex network of friendship and enmity relations.Comment: 7 pages, 5 figures, accepted for publication in PNA

OH 12.8-0.9: A New Water-Fountain Source

We present observational evidence that the OH/IR star OH 12.8-0.9 is the fourth in a class of objects previously dubbed "water-fountain" sources. Using the Very Long Baseline Array, we produced the first images of the water maser emission associated with OH 12.8-0.9. We find that the masers are located in two compact regions with an angular separation of ~109 mas on the sky. The axis of separation between the two maser regions is at a position angle of 1.5 deg. East of North with the blue-shifted (-80.5 to -85.5 km/s) masers located to the North and the red-shifted (-32.0 to -35.5 km/s) masers to the South. In addition, we find that the blue- and red-shifted masers are distributed along arc-like structures ~10-12 mas across oriented roughly perpendicular to the separation axis. The morphology exhibited by the water masers is suggestive of an axisymmetric wind with the masers tracing bow shocks formed as the wind impacts the ambient medium. This bipolar jet-like structure is typical of the three other confirmed water-fountain sources. When combined with the previously observed spectral characteristics of OH 12.8-0.9, the observed spatio-kinematic structure of the water masers provides strong evidence that OH 12.8-0.9 is indeed a member of the water-fountain class.Comment: 12 pages, 2 figures (1 color), accepted for publication in the Ap J Letter

Cruise summaries of Oceanus cruises 205, leg 8, and 216

A study of the upper ocean thermal and density structure in the northwestern Atlantic in 1989 compared temperature and density measurements made with Expendable Bathythermograph (XBT) and Conductivity-Temperature-Depth instruments with current data from an acoustic Doppler current profiler and satellite infrared imagery and altimetry. Two cruises were made in the spring and winter of 1989 with the goal of directly measuring the upper ocean currents and variabilty of the Gulf Stream. The XBT observations were used to extend the measured velocities geostrophically from the near-surface region to depths of 750 meters, thereby allowing transport estimates to be made for the upper ocean. In April the measurments were compared and used with the GEOSAT altimeter which, unfortunately, was not operating during the December cruise.Funding was provided by the National Science Foundation through Grant No. OCE-SS-1769S

Pengobatan Artesunat pada Penderita Malaria Falsiparum tanpa Komplikasi di Daerah Resisten Multidrug

A treatment trial of artesunate for uncomplicated falciparum malaria cases was conducted at ITCI Hospital, Balikpapan, East Kalimantan, Indonesia, in November 1992 - Januari 1993. The objectives of this study were to assess the efficacy and safety of artesunate. Thirty eight falcipamm malaria patients who had been selected according to criteria for the in vivo sensitivity test were treated orally with 100 mg artesunate 12 hourly on DO and followed 50 mg 12 hourly on Dl-4. All patients were hospitalized until declared cured clinically and parasitologicalty. The most prevalent clinical symptoms of these malaria patients were fever (84,2%), headache (81,6%), nausea (73,7%) and splenomegaly (71,0%o). The cure rates of artesunate were 100% (38/38 and 28/28) on D7 and D14, but on D21 and D28 there were 88,2% (15/17) and 75% (6/8) because of the presence of late Rl cases. The mean fever clearance time (FCT) and parasite clearance time (PCT) were as follows 15,1 1,8 h and 32,1 3,0 h (D7), 14,1 2,2 h and 33,3 3,8 h (D14), 15,7 3,0 h and 37,6 5,6 h (D21), 14,0 4,6 h and 32,0 5,9 h (D28) respectively. No side effect was found clinically and on laboratory examinations. Artesunate is effective and safe for treatment of uncomplicated falciparum malaria until D14 in a multidrug resistant area. A sequential combination of artesunate and other antimalarial drugs should be studied to achieve a radical cure

The vacuum bubbles in de Sitter background and black hole pair creation

We study the possible types of the nucleation of vacuum bubbles. We classify vacuum bubbles in de Sitter background and present some numerical solutions. The thin-wall approximation is employed to obtain the nucleation rate and the radius of vacuum bubbles. With careful analysis we confirm that Parke's formula is also applicable to the large true vacuum bubbles. The nucleation of the false vacuum bubble in de Sitter background is also evaluated. The tunneling process in the potential with degenerate vacua is analyzed as the limiting cases of the large true vacuum bubble and false vacuum bubble. Next, we consider the pair creation of black holes in the background of bubble solutions. We obtain static bubble wall solutions of junction equation with black hole pair. The masses of created black holes are uniquely determined by the cosmological constant and surface tension on the wall. Finally, we obtain the rate of pair creation of black holes.Comment: 3 figures, minor including errors and typos corrected, and refs. adde

USNS Bartlett cruise 40-B data report

A joint cruise with Dr. Michael Gregg of the Applied Physics Laboratory at the University of Washington was conducted from 8-24 January, 1983, aboard the USNS Bartlett to study the effects of wintertime cooling in a warm core ring. At the beginning of the cruise an XBT survey of ring 821 (found at 40°40'N, 66°W, east of the New England Seamounts) showed a rather confused pattern of surface temperature and salinity with the average depth of the mixed layer about 30m. On January 16-17, a storm passed near the ring with winds to 45 knots and temperatures below 0°C. An XBT survey at the end of the cruise showed that vertical mixing and cooling during the outbreak of cold air resulted in a more coherent pattern in the surface temperature and salinity of the ring and an increase in the thickness of the mixed layer to 180 m.Prepared for the Office of Naval Research under Contract N00014-82-C-0019; NR 083-004

GREAT [CII] and CO observations of the BD+40{\deg}4124 region

The BD+40\degree4124 region was observed with high angular and spectral resolution with the German heterodyne instrument GREAT in CO J = 13 \rightarrow 12 and [CII] on SOFIA. These observations show that the [CII] emission is very strong in the reflection nebula surrounding the young Herbig Ae/Be star BD+40\degree4124. A strip map over the nebula shows that the [CII] emission approximately coincides with the optical nebulosity. The strongest [CII] emission is centered on the B2 star and a deep spectrum shows that it has faint wings, which suggests that the ionized gas is expanding. We also see faint CO J = 13 \rightarrow 12 at the position of BD+40\degree4124, which suggests that the star may still be surrounded by an accretion disk.We also detected [CII] emission and strong CO J = 13 \rightarrow 12 toward V1318 Cyg. Here the [CII] emission is fainter than in BD+40\degree4124 and appears to come from the outflow, since it shows red and blue wings with very little emission at the systemic velocity, where the CO emission is quite strong. It therefore appears that in the broad ISO beam the [CII] emission was dominated by the reflection nebula surrounding BD+40\degree4124, while the high J CO lines originated from the adjacent younger and more deeply embedded binary system V1318 Cyg

Mechanisms of Hemolysis-Associated Platelet Activation

Background Intravascular hemolysis occurs after blood transfusion, in hemolytic anemias, and in other conditions, and is associated with hypercoagulable states. Hemolysis has been shown to potently activate platelets in vitro and in vivo, and several mechanisms have been suggested to account for this, including: (i) direct activation by hemoglobin (Hb); (ii) increase in reactive oxygen species (ROS); (iii) scavenging of nitric oxide (NO) by released Hb; and (iv) release of intraerythrocytic ADP. Objective To elucidate the mechanism of hemolysis-mediated platelet activation. Methods We used flow cytometry to detect PAC-1 binding to activated platelets for in vitro experiments, and a Siemens\u27 Advia 120 hematology system to assess platelet aggregation by using platelet counts from in vivo experiments in a rodent model. Results We found that Hb did not directly activate platelets. However, ADP bound to Hb could cause platelet activation. Furthermore, platelet activation caused by shearing of red blood cells (RBCs) was reduced in the presence of apyrase, which metabolizes ADP to AMP. The use of ROS scavengers did not affect platelet activation. We also found that cell-free Hb enhanced platelet activation by abrogating the inhibitory effect of NO on platelet activation. In vivo infusions of ADP and purified (ADP-free) Hb, as well as hemolysate, resulted in platelet aggregation, as shown by decreased platelet counts. Conclusion Two primary mechanisms account for RBC hemolysis-associated platelet activation: ADP release, which activates platelets; and cell-free Hb release, which enhances platelet activation by lowering NO bioavailability