33,602 research outputs found
SPICE modelling of photoluminescence and electroluminescence based current-voltage curves of solar cells for concentration applications
Quantitative photoluminescence (PL) or electroluminescence (EL) experiments can be used to probe fast and in a non-destructive way the current-voltage (IV) characteristics of individual subcells in a multi-junction device, information that is, otherwise, not available. PL-based IV has the advantage that it is contactless and can be performed even in partly finished devices, allowing for an early diagnosis of the expected performance of the solar cells in the production environment. In this work we simulate the PL- and EL-based IV curves of single junction solar cells to assess their validity compared with the true IV curve and identify injection regimes where artefacts might appear due to the limited in-plane carrier transport in the solar cell layers. We model the whole photovoltaic device as a network of sub-circuits, each of them describing the solar cell behaviour using the two diode model. The sub-circuits are connected to the neighbouring ones with a resistor, representing the in-plane transport in the cell. The resulting circuit, involving several thousand subcircuits, is solved using SPICE
Integrability and chemical potential in the (3+1)-dimensional Skyrme model
Using a remarkable mapping from the original (3+1)dimensional Skyrme model to
the Sine-Gordon model, we construct the first analytic examples of Skyrmions as
well as of Skyrmions--anti-Skyrmions bound states within a finite box in 3+1
dimensional flat space-time. An analytic upper bound on the number of these
Skyrmions--anti-Skyrmions bound states is derived. We compute the critical
isospin chemical potential beyond which these Skyrmions cease to exist. With
these tools, we also construct topologically protected time-crystals:
time-periodic configurations whose time-dependence is protected by their
non-trivial winding number. These are striking realizations of the ideas of
Shapere and Wilczek. The critical isospin chemical potential for these
time-crystals is determined.Comment: 15 pages; 1 figure; a discussion on the closeness to the topological
bound as well as some clarifying comments on the semi-classical quantization
have been included. Relevant references have been added. Version accepted for
publication on Physics Letters
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Agency, Liberation, and Intersectionality among Latina Scholars: Narratives from a Cross-institutional Writing Collective
Among United States residents, the number of doctoral degrees conferred to Latinx students represents a small percentage compared to other groups. For example, from 2009–2010, the percentage of degrees conferred to Latinx students was 5 percent compared to 74 percent for White students, 11 percent for Asian/Pacific Islanders, 7 percent for African Americans, and 0.7 percent for Indian/Alaska Natives. During the same period, the proportion of doctoral degrees conferred to females was 55 percent for Latinas compared to 65 percent for African American students, 56 percent for Asian/Pacific students, 54 percent for American Indian/Alaska Native students, and 51 percent for White female students (National Center for Education Statistics). Historically, underrepresented minority (URM) students encounter a plethora of issues that influence their educational experiences, yet there is a scarcity of scholarship that elucidates the quality of experience of women of color (WOC) pursuing doctorate degrees (Aryan and Guzman). As multi-marginalized, firstgeneration college students, we continuously struggle to find a place within higher education. Our educational pathways to becoming doctoral recipients have occurred primarily within the context of alienation, significantly influencing our need to connect with other WOC who have also felt isolated and disconnected. Consequently, we needed to find each other because knowing that there were other Latinas in doctoral programs, and actually getting to know them, validated our existence within academiaUniversity Writing Cente
Revisiting Minimal Lepton Flavour Violation in the Light of Leptonic CP Violation
The Minimal Lepton Flavour Violation (MLFV) framework is discussed after the
recent indication for CP violation in the leptonic sector. Among the three
distinct versions of MLFV, the one with degenerate right-handed neutrinos will
be disfavoured, if this indication is confirmed. The predictions for leptonic
radiative rare decays and muon conversion in nuclei are analysed, identifying
strategies to disentangle the different MLFV scenarios. The claim that the
present anomalies in the semi-leptonic -meson decays can be explained within
the MLFV context is critically re-examined concluding that such an explanation
is not compatible with the present bounds from purely leptonic processes.Comment: 36 pages, 4 figures. V2: References added; version accepted for
publication on JHE
Conformal Invariance of the Pure Spinor Superstring in a Curved Background
It is shown that the pure spinor formulation of the heterotic superstring in
a generic gravitational and super Yang-Mills background has vanishing one-loop
beta functions.Comment: Reference adde
Space-time noncommutativity and (1+1) Higgs Model
We compare the classical scattering of kinks in (1+1) Higgs model with its
analogous noncommutative counterpart. While at a classical level we are able to
solve the scattering at all orders finding a smooth solution, at a
noncommutative level we present only perturbative results, suggesting the
existence of a smooth solution also in this case.Comment: 18 pages, 2 figure
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