Karthik Shekhar Profile
Karthik Shekhar

@shekharlab

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Assistant Professor, UC Berkeley (CBE and Helen Wills Neuroscience Institute)

Berkeley, CA
Joined May 2019
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@shekharlab
Karthik Shekhar
1 year
Preprint alert: Electrical signaling in all living cells involves localized currents through ion transporters and ion channels. But these fluxes must then reorganize ions around the cell's lipid membrane. How does this reorganization occur?.
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@shekharlab
Karthik Shekhar
27 days
RT @PhysRevE: This study was conducted by Jafar Farhadi, @shekharlab, Kranthi Mandadapu, and colleagues at @UCBerkeley.
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@shekharlab
Karthik Shekhar
3 months
RT @KLabVision: The ON/OFF dichotomy is fundamental to visual processing. In a new study led by Flori Soto, we identify a conserved molecul….
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@shekharlab
Karthik Shekhar
4 months
RT @PhysRevResearch: Spatiotemporal dynamics of ionic reorganization near biological membrane interfaces, Hyeongjoo Row, Joshua B. Fernande….
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@shekharlab
Karthik Shekhar
7 months
RT @RachanaDSomaiya: New preprint! 🔥A wonderful collaboration of our @FellerMarla lab with Matthew Po, and @shekharlab. Here, we dive into….
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@shekharlab
Karthik Shekhar
8 months
Full credit to my student Alhad Deshpande (co-advised by Kranthi) for composing this thread, in addition to leading this work. I am merely the medium! (14/14).
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@shekharlab
Karthik Shekhar
8 months
Finally, we hope that this work inspires experimentation of viscodiffusive fluids and the exploration of other cross-coupled odd transport phenomena, in both active and passive systems. (13/14).
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@shekharlab
Karthik Shekhar
8 months
Finally, we also argue that odd viscodiffusion is fully consistent with the Curie symmetry principle as originally formulated by P. Curie (1894). (12/14).
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@shekharlab
Karthik Shekhar
8 months
Moreover, we’re able to identify chiral bacterial solutions as viscodiffusive fluids, and reinterpret previous microfluidic experiments () under the lens of odd transport phenomena! (11/14)
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@shekharlab
Karthik Shekhar
8 months
Odd viscodiffusive fluids can demonstrate some cool behavior! We can construct a “chiral generator” that induces a solute current through mechanical rotation and a reciprocal “chiral engine” that generates mechanical motion when maintaining a concentration gradient. (10/14)
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@shekharlab
Karthik Shekhar
8 months
In the case of passive viscodiffusive fluids, the FH allows us to develop a reciprocal relation (à la Onsager!), unifying viscodiffusive transport under one coefficient! (9/14)
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@shekharlab
Karthik Shekhar
8 months
The FH enabled us to derive Green-Kubo relations that show how viscodiffusion arises in chiral fluids in 3D. Remarkably, unlike the case of odd diffusion and odd viscosity, these fluids may be either passive or active! Thus, all chiral fluids are viscodiffusive! (8/14)
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@shekharlab
Karthik Shekhar
8 months
This is where we used the Flux Hypothesis, an extension of the Onsager Regression Hypothesis, proposed recently by Alhad, Cory, Ahmad Omar and Kranthi ( - to understand the microscopic origins of viscodiffusion. (7/14).
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@shekharlab
Karthik Shekhar
8 months
Through the lens of representation theorems, we show that these “viscodiffusive” couplings are strictly odd! Classically, these have been neglected through misinterpretations of the famed Curie Symmetry Principle. But when do these couplings appear? (6/14)
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@shekharlab
Karthik Shekhar
8 months
But it has long been appreciated that fluxes can arise from any driving force present (e.g. Dufor and Soret effects). We reasoned that mass fluxes may arise from velocity gradients and mechanical stresses may arise from concentration gradients, which we term “viscodiffusion.”
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@shekharlab
Karthik Shekhar
8 months
In 3D isotropic systems, the diffusion and viscosity tensors have no odd contributions! How then can 3D odd transport then come about? (4/14)
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@shekharlab
Karthik Shekhar
8 months
Odd transport phenomena couple fluxes to spatially orthogonal driving forces. Previous studies of isotropic odd transport, such as odd diffusion and odd viscosity, have largely involved 2D systems that are both chiral and active (driven). But what about 3D systems? (3/14)
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@shekharlab
Karthik Shekhar
8 months
With Alhad Deshpande, @coryhargus, and Kranthi K. Mandadapu, we show how helical objects, like this cavatappi, can demonstrate "odd" transport phenomena in 3D by interconverting mechanical and chemical energy. (2/14).
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@shekharlab
Karthik Shekhar
8 months
New preprint alert! What does this bowl of pasta have to do with the fundamentals of transport phenomena? (1/14)
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@shekharlab
Karthik Shekhar
8 months
RT @brainevodevo: @JenelleLWallace led a preview of two outstanding papers from @CcileCharrier , @blibep , @VanderhaeghenP2 , @fpolleux et….
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@shekharlab
Karthik Shekhar
8 months
RT @suri_lab: Check out new work by Alexandra, Agnish, Aditya and Cal on generative diffusion but with correlated….
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