Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential lies in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultrawideband tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light-emitting devices to touch screens, photodetectors and ultrafast lasers. Here we review the state-of-the-art in this emerging field.

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Graphene photonics and optoelectronics

BACKGROUND Materials by design is an appealing idea that is very hard to realize in practice. Combining the best of different ingredients in one ultimate material is a task for which we currently have no general solution. However, we do have some successful examples to draw upon: Composite materials and III-V heterostructures have revolutionized many aspects of our lives. Still, we need a general strategy to solve the problem of mixing and matching crystals with different properties, creating combinations with predetermined attributes and functionalities. ADVANCES Two-dimensional (2D) materials offer a platform that allows creation of heterostructures with a variety of properties. One-atom-thick crystals now comprise a large family of these materials, collectively covering a very broad range of properties. The first material to be included was graphene, a zero-overlap semimetal. The family of 2D crystals has grown to includes metals (e.g., NbSe 2 ), semiconductors (e.g., MoS 2 ), and insulators [e.g., hexagonal boron nitride (hBN)]. Many of these materials are stable at ambient conditions, and we have come up with strategies for handling those that are not. Surprisingly, the properties of such 2D materials are often very different from those of their 3D counterparts. Furthermore, even the study of familiar phenomena (like superconductivity or ferromagnetism) in the 2D case, where there is no long-range order, raises many thought-provoking questions. A plethora of opportunities appear when we start to combine several 2D crystals in one vertical stack. Held together by van der Waals forces (the same forces that hold layered materials together), such heterostructures allow a far greater number of combinations than any traditional growth method. As the family of 2D crystals is expanding day by day, so too is the complexity of the heterostructures that could be created with atomic precision. When stacking different crystals together, the synergetic effects become very important. In the first-order approximation, charge redistribution might occur between the neighboring (and even more distant) crystals in the stack. Neighboring crystals can also induce structural changes in each other. Furthermore, such changes can be controlled by adjusting the relative orientation between the individual elements. Such heterostructures have already led to the observation of numerous exciting physical phenomena. Thus, spectrum reconstruction in graphene interacting with hBN allowed several groups to study the Hofstadter butterfly effect and topological currents in such a system. The possibility of positioning crystals in very close (but controlled) proximity to one another allows for the study of tunneling and drag effects. The use of semiconducting monolayers leads to the creation of optically active heterostructures. The extended range of functionalities of such heterostructures yields a range of possible applications. Now the highest-mobility graphene transistors are achieved by encapsulating graphene with hBN. Photovoltaic and light-emitting devices have been demonstrated by combining optically active semiconducting layers and graphene as transparent electrodes. OUTLOOK Currently, most 2D heterostructures are composed by direct stacking of individual monolayer flakes of different materials. Although this method allows ultimate flexibility, it is slow and cumbersome. Thus, techniques involving transfer of large-area crystals grown by chemical vapor deposition (CVD), direct growth of heterostructures by CVD or physical epitaxy, or one-step growth in solution are being developed. Currently, we are at the same level as we were with graphene 10 years ago: plenty of interesting science and unclear prospects for mass production. Given the fast progress of graphene technology over the past few years, we can expect similar advances in the production of the heterostructures, making the science and applications more achievable.

2D materials and van der Waals heterostructures

Real-time prediction of massive transfusion during cesarean section using intraoperative hemodynamic monitoring data

We report optical scanning measurements on photocurrent in individual Germanium nanowire transistors. Photoconductivity measurements reveal that Germanium nanowire can be used as an ultrasensitive, nanoscale photodetectors, especially in the visible range. The photoconductivity shows a strong saturation behavior unlike Schottky photocurrents observed at the metal contacts.

Scanning Photoconductivity and Photocurrent Imaging in Germanium Nanowires

Background The rate of the prenatal diagnosis of congenital heart disease is increasing along with advances in fetal echocardiography techniques. Here, we aimed to investigate the trend of the use of fetal echocardiography over time and to compare the medical costs of congenital heart disease treatment according to whether fetal echocardiography was performed. Methods We reviewed our hospital’s database, and patients who underwent the first surgery for congenital heart disease within 30 days of birth during 2005–2007, 2011–2013, and 2017–2019 were included. The severity of congenital heart disease diagnosed in each case was evaluated according to The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Scores (STS-EACTS Mortality Scores) and Mortality Categories (STAT Mortality Categories). Results In total, 375 patients were analyzed, and fetal echocardiography use increased significantly after the 2010s compared with in 2005–2007 (19.1% vs. 39%, p = 0.032 in Mortality Category 1–3; 15.5% vs. 69.5%, p = 0.000 in Mortality Category 4–5). Additionally, the mean STS-EACTS Mortality Score was higher in prenatally diagnosed patients than in postnatally diagnosed patients (2.287 vs. 1.787, p = 0.001). In the recent period, there was no significant difference in hospitalization durations and medical costs according to whether or not fetal echocardiography was performed. Conclusions This single center study showed the use of fetal echocardiography is increasing. Further, prenatal diagnosis with fetal echocardiography causing no differences in medical costs in recent years. Therefore, we suggest that fetal echocardiography can be applied more widely without increasing the economic burden.

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Trend of fetal echocardiography use and comparison of medical costs for congenital heart disease treatment based on fetal echocardiography use in a Korean single center

Using ultrafast microscopy we find bound interlayer excitons in twisted bilayer graphene. By quantifying the binding energy, photoluminescence and ultrafast photocurrent we show such bilayer quantum materials enable fast, broadband photosensing.

Jiwoong Park

Papers

Real-time prediction of massive transfusion during cesarean section using intraoperative hemodynamic monitoring data

Scanning Photoconductivity and Photocurrent Imaging in Germanium Nanowires

Trend of fetal echocardiography use and comparison of medical costs for congenital heart disease treatment based on fetal echocardiography use in a Korean single center

Tunable Photocurrent and Photoluminescence from Interlayer Excitons in Twisted Bilayer Graphene and 2D Semiconductors

Diverse cardiovascular risk of recurrent spontaneous abortion: A prospective cohort study using UK Biobank