Excitonic Stark effect in MoS2_2 monolayers

We theoretically investigate excitons in MoS$_2$ monolayers in an applied in-plane electric field. Tight-binding and Bethe-Salpeter equation calculations predict a quadratic Stark shift, of the order of a few meV for fields of 10 V/$\mu$m, in the linear absorption spectra. The spectral weight of the main exciton peaks decreases by a few percent with an increasing electric field due to the exciton field ionization into free carriers as reflected in the exciton wave functions. Subpicosecond exciton decay lifetimes at fields of a few tens of V/$\mu$m could be utilized in solar energy harvesting and photodetection. We find simple scaling relations of the exciton binding, radius, and oscillator strength with the dielectric environment and an electric field, which provides a path to engineering the MoS$_2$ electro-optical response.Comment: 9 pages, 7 figure

Characterizing network paths in and out of the clouds

Commercial Cloud computing is becoming mainstream, with funding agencies moving beyond prototyping and starting to fund production campaigns, too. An important aspect of any scientific computing production campaign is data movement, both incoming and outgoing. And while the performance and cost of VMs is relatively well understood, the network performance and cost is not. This paper provides a characterization of networking in various regions of Amazon Web Services, Microsoft Azure and Google Cloud Platform, both between Cloud resources and major DTNs in the Pacific Research Platform, including OSG data federation caches in the network backbone, and inside the clouds themselves. The paper contains both a qualitative analysis of the results as well as latency and throughput measurements. It also includes an analysis of the costs involved with Cloud-based networking.Comment: 7 pages, 1 figure, 5 tables, to be published in CHEP19 proceeding

Defining a canonical unit for accounting purposes

Compute resource providers often put in place batch compute systems to maximize the utilization of such resources. However, compute nodes in such clusters, both physical and logical, contain several complementary resources, with notable examples being CPUs, GPUs, memory and ephemeral storage. User jobs will typically require more than one such resource, resulting in co-scheduling trade-offs of partial nodes, especially in multi-user environments. When accounting for either user billing or scheduling overhead, it is thus important to consider all such resources together. We thus define the concept of a threshold-based "canonical unit" that combines several resource types into a single discrete unit and use it to characterize scheduling overhead and make resource billing more fair for both resource providers and users. Note that the exact definition of a canonical unit is not prescribed and may change between resource providers. Nevertheless, we provide a template and two example definitions that we consider appropriate in the context of the Open Science Grid.Comment: 6 pages, 2 figures, To be published in proceedings of PEARC2

Vaginal cuff recurrence after radical cystectomy: an under - studied site of bladder cancer relapse

Vaginal cuff recurrence of tumor following radical cystectomy is a rare site of disease recurrence, however it has never been specifically studied. The aim of the study is to evaluate incidence, risk factors, and long-term oncologic outcomes of vaginal cuff recurrence in a cohort of female patients treated with radical cystectomy for invasive urothelial carcinoma of the bladder