Integrated Calendar

The effects of ocean circulation on the climate’s response to anthropogenic emissions at low and high latitudes are examined. At high latitudes, we examine the effects of ocean circulation on the North Atlantic sea surface temperature, which has large climate impacts in the Northern Hemisphere. In recent years and in climate projections a cooling trend is found in the North Atlantic surface (the North Atlantic warming hole). Using observations and large ensemble of model simulations, we find that since the beginning of 21st century there has been a reduction in surface meridional heat advection, which cools the North Atlantic midlatitudes and is part of an emerged forced response to anthropogenic emissions and not part of internal climate variability, and thus projected to continue in coming decades.

At low latitudes, the Hadley cell plays an important role in setting the strength and position of the hydrological cycle. Climate projections show a weakening of the Hadley cell, together with widening of its vertical and meridional extents. These changes are projected to have profound global climatic impacts. Current theories for the Hadley cell response to increased greenhouse gases account only for atmospheric and oceanic thermodynamic changes, but not for oceanic circulation changes. Here, the effects of ocean circulation changes on the Hadley cell response to increased greenhouse gases are examined. First, using a hierarchy of ocean-model configurations under increased greenhouse gases or arctic sea-ice loss, we show that, by cooling the surface and atmosphere, ocean circulation contracts and strengthens the Hadley cell, and thus reduces its projected response.

The term “ocean waves” typically evokes images of surface waves shaking ships during storms in the open ocean, or breaking rhythmically near the shore. Yet much of the ocean wave action takes place far underneath the surface, and consists of surfaces of constant
density being disturbed and modulated. These -internal waves- are ubiquitous in the ocean, contain a large amount of ocean energy, and play an important role in the ocean circulation since they transfer energy from large to small scales and thus provide a link between climatological forcing and small-scale dissipation.
Yet, despite internal wave ubiquity, energy, and decades of study we still do not understand how the energy cascades through the internal wave spectrum.
In this talk the traditional wave turbulence formulation of internal wave interaction will be discussed, and rebutted: internal waves are too nonlinear to be accurately described by the kinetic equation. So we are in the midst of something gloriously messy and nonlinear. We
will propose an alternative formulation based on the hypothesis of scale separated (nonlocal) interactions in momentum space.

This is joined work with Dr. Kurt Polzin from whoi.edu

Homologous recombination is an engine of genetic diversity in evolution and in plant breeding. This process typically occurs during meiosis when homologous chromosomes pair and exchange DNA segments. It is a stochastic and infrequent process; closely linked genes rarely recombine and it is limited to sexual reproduction. We showed recently that inter-homologues recombination can be targeted at specific loci, using a CRISPR-Cas-induced DNA double strand break in plant somatic tissues. We discuss the mechanisms of somatic recombination and the prospect for redesigning chromosomes in a targeted manner in crops with or without sexual reproduction.

Episodic memory – the ability to encode, maintain and retrieve information – is critical for everyday functioning at all ages, yet little is known about the development of episodic memory systems and their brain substrates. In this talk, I will present data from a series of studies with which we begin to identify how brain development underlies changes in episodic memory throughout childhood and adolescence. Using structural MRI data, I will present evidence demonstrating how brain development sets limits on cognitive developmnet. I will show that individual differences in fine structural measures of the hippocampus, a region known to be critical for episodic memory, and the prefrontal cortex (PFC), a region that shows protracted structural development, partially explain age-related improvement in episodic memory. Using functional neuroimaging methods including functional MRI (fMRI) and electrocorticography (ECoG), I will present our ongoing attempts to characterize the neural correlates of episodic memory development. Evidence from fMRI studies suggest that age differences in episodic memory functioning may primarily relate to age differneces in PFC activation and connectivity patterns. Intracranial evidence further underscores the role of the PFC in memory and reveals that spatiotemporal propagation of frontal activity supports memory formation in children. I will highlight the challenges in investigaitons of brain-behavior relations in pediatric populations and discuss how advances in methodologies provide unique opportunities for moving towards a mechanistic understanding of developmental changes.

Since the first demonstration of laser cooling and trapping three decades ago, our abilities to manipulate atomic ensembles and individual atoms with light have been substantially extended. Among those novel capabilities, I will discuss a new method how to directly optically cool an atomic gas to form a Bose-Einstein condensate, without any evaporation. I will also discuss the deterministic preparation of a large array of individual atoms with controlled optically induced long-range Ising type interactions for quantum simulation, and potentially, quantum computing.