Animals modify their behaviors in response to changes in their external social environment and internal physiological state to maximize their chances of survival and reproduction. This behavioral flexibility allows animals to have different responses to the same sensory stimulus depending on the needs of the animals and their environment. To understand how such flexibility arises in the nervous system, we studied how social environment can modulate mating behavior in the vinegar fly, Drosophila melanogaster. We found that when mature male flies are raised in an environment of high population density, they enhance their courtship display towards females. A similar enhancement is not observed in immature males, suggesting that there is an interaction between signals arising from the internal state (reproductive maturity) and the external environment (population density) of the fly. We identified the neural substrate of this behavioral modulation as plasticity in a single type of aphrodisiac pheromone sensing neuron that enhances its pheromone sensitivity only in mature males raised in dense housing conditions. Neuronal sensitization is induced by a synergistic interaction between juvenile hormone, a signal for reproductive maturity, and activity-dependent signaling pathways. Further, the adaptive responses of pheromone sensing neurons are sexually dimorphic in nature - they are observed in males but not in females. Sex differences in neuronal plasticity are regulated by FruitlessM, a male-specific transcription factor that regulates pheromone sensitivity in these neurons. Our findings indicate that FruitlessM likely functions as a genomic coincidence detector—integrating internal reproductive maturity and external population density—to modulate mating behavior in a sexually dimorphic manner.

Mechanistic studies into cellular and molecular basis of behavioral flexibility are largely possible due to the availability of genetic tools that allow precise manipulations of neural circuits. In a parallel effort, we expanded the fly toolkit by developing a new method to alter gene expression in a spatially and temporally controlled manner, and demonstrated its utility in mapping and manipulating neuronal circuits underlying odor preference behavior. We anticipate that the development of these tools will further advance our understanding of how internal state and environmental context modulate behaviors in an integrated fashion.

A techno-economic analysis was conducted for a 100% renewable energy-based standalone microgrid system comprising of solar PV, battery energy storage and Power to Hydrogen(P2H) system (comprised of Electrolyzer, Fuel Cell and Hydrogen Storage Tank). Hydrogen is gaining widespread interest globally as an energy carrier as well as a storage medium. This study evaluates the potential of hydrogen systems to utilize (in fuel cells) and store (in the form of compressed hydrogen) excess renewable electricity generated which otherwise would be curtailed.Four scenarios (including a diesel generator only base-case scenario) were investigated for a 25 year project lifetime period to select the most optimal set of energy technologies to meet load requirements of a microgrid in San Diego, CA. The microgrid had an electrical load of around 2900 kWh/day and peak annual load of 312 kW. The microgrid design optimization tool HOMER Pro was used to design, model, and simulate the energy technologies and to analyze and compare the energy balance, economics, and environmental emissions amongst the proposed scenarios. A sensitivity analysis was performed to evaluate design robustness against the uncertainty pertaining to fuel cell and electrolyzer costs. The simulation results showed that a hydrogen-battery based renewable hybrid energy storage system minimized total net present cost, and levelized cost of energy technologies. The proposed hybrid energy system has the potential to be deployed to a 100% renewable energy based standalone microgrid system, with low energy generation costs and facilitating in decarbonization efforts.

It has been universally assumed that sensible qualities—colors, smells, shapes and sizes—must either be “out there” or “in here”: they must either be features of the external world or modifications of perceivers’ minds. Neither option is satisfying, because both force us to relinquish the striking intuition that there is something shared by a tomato and an after-image, a beach ball and a phosphene, when each is said to look red or to look round. The central insight of my dissertation is that the choice between sensible qualities being “out there” or “in here” is a false one: it stems from a misunderstanding of the metaphysics of sensible qualities. The mind and the material world play distinct roles in the instantiation of sensible qualities: material bodies are the bearers of sensible qualities; minds perceive these qualities. Each guarantees an instance of the quality, but does so in a way that does not exclude the other. These observations concerning the metaphysical nature of sensible qualities have expansive ramifications for the philosophy of mind; for at bottom, they reveal that the mind and the world play supportive, rather than antagonistic, roles in the constitution of conscious phenomenology.

In my dissertation, I develop a historically motivated account of two kinds of sensible instances. The redness of an ordinary tomato is a mind-independent sensible instance because inherence in the physical tomato is all that is required for this instance to exist. I trace this notion of inherence back to Locke, arguing that for him, inherence in a substance is what explains the instantiation of a sensible quality. But now consider an experience of a red after-image. We cannot describe the phenomenology of this experience by appeal to an uninstantiated universal; for this fails to capture how the redness that you experience is right there in front of you, not in Platonic heaven. So there must be an actual instance of redness present. But, unlike in the case of the tomato, there is no suitable object for redness to inhere in. There is no material body that is red; nor can the mind serve as the bearer of redness, for this would have the absurd implication that the mind, when perceiving, is itself literally red. Arguing that this is the real insight behind Berkeley’s famous maxim esse est percipi, I defend the view that such an instance of redness exists, not in virtue of having any bearer (contra Locke), but rather as the object of a perceiver’s awareness. Just as in the case of pains, the very fact that a perceiver enjoys an experience of a red after-image guarantees an instance of redness of which she is aware.

Thus, sensible qualities turn out to be an ontologically flexible kind—some instances inhere in material bodies, others are the objects of a perceiver’s mental states. More importantly, however, the two modes of instantiation are not exclusive of each other even in the case of a particular instance. Consider, for example, a case in which one perceives a ripe tomato: in this situation, two conditions obtain, each of which is sufficient for the instantiation of redness. First, there is a material object—the tomato—that redness inheres in. But second, the perceiver is in a mental state whose existence guarantees an instance of redness. In such a case, given that there is only one instance of redness present, it must be over-determined. A perceived instance of redness, then, simultaneously inheres in a physical object and is the object of a perceiver’s awareness.

I use this framework to develop a novel version of naïve realism—the view that ordinary perception is constitutively an awareness of the mind-independent world—which acknowledges the rich phenomenology of hallucinations. There has been unanimous agreement that this combination of features is impossible to secure. For given the absence of a physical object, if a hallucination makes the perceiver aware of redness, it must make the perceiver aware of a mind-dependent instance of redness. Many have argued, though, that if the hallucinated instance is mind-dependent, it seems as though the instance of redness in the veridical perception must be as well, thereby falsifying naïve realism.

First, I argue that representationalism—the view most commonly endorsed by those who accept the argument—is unable to do justice to the phenomenology of experience. But then, I go on to show that the argument is invalid, thereby defending naïve realism. I argue that both veridical and hallucinatory acts of awareness are individually sufficient for their items, but it is only the instances in the hallucination that are mind-dependent. For remember that the instance of redness in the veridical case is over-determined: despite the sufficiency of the perceiver’s state, the presence of a material body that is itself sufficient for the instance in question means that this instance can outlive the experience, continuing to inhere, now unperceived, in the tomato. This makes the items of veridical perception mind-independent. Nonetheless, veridical perception and hallucination have the same phenomenal character, because both comprise an awareness of the same sensible qualities. The contribution that particular instances of these qualities make to conscious phenomenology is unaffected by their ontological status—that is, by whether or not they are mind-independent. In paying close attention to the underlying metaphysics, then, we have established the world-involving nature of perception while nonetheless respecting the mind’s capacity to generate phenomenal character.

We present a multi-disciplinary framework for motion modeling and recognition in machine vision. Building upon the neurobiological model of motion recognition, we propose computational equivalents for the Motion Energy and Form Pathways. We derive the Hamiltonian Energy Signature (HES) from first-principles in physics as the basis for the Motion Energy Pathway. The Form Pathway is modeled using existing low-level feature descriptors based on shape, appearance, and gradients. We propose an Integration methodology to combine both pathways using a variant of the Feature Integration and Biased Competition neurobiological models, which we implement via statistical hypothesis testing using the bootstrap. We also show the extensibility of our physics-based approach by proposing a physically-significant, compact representation for the gait of a person called the Gait Action Image (GAI), which is based on core physics principles employed in the HES formulation. We then show the generalizability of our neurobiologically-inspired integration framework by casting the GAI within this infrastructure.

Since Motion and image analysis are both important for activity recognition in video, we also develop a new approach that extends the Hamiltonian Monte Carlo (HMC) to allow us to simultaneously search over the combined motion and image space in a concerted manner using well-known Markov Chain Monte Carlo (MCMC) techniques. For motion analysis in video, we use tracks generated from the video to calculate the Hamiltonian equations of motion for the systems under study, thus utilizing analytical Hamiltonian dynamics to derive a physically significant HMC algorithm which can be used for activity analysis. We then use image analysis to help explore both the motion energy space and the image space by integrating the Hamiltonian energy-based approach with an image-based data-driven proposal to drive the HMC, thereby yielding a Data Driven HMC (DDHMC). We reduce the enormity of the search space by driving the Hamiltonian dynamics-based MCMC with image data in this DDHMC. We also develop the reverse algorithm, which uses motion energy proposals to search the image space. While HMC has been used in other contexts, this is possibly the first work that shows how it can be used for activity recognition in video, taking into account the image analysis results and using the physical motion information of the system. In addition, the DDHMC framework has potential application to other domains where statistical sampling techniques are useful, as we outline in the section on future work.

Experimental validation of the theory is provided on the well-known KTH, Weizmann, and USF Gait datasets with very promising results.

Kant on Subjectivity and Self-Consciousness

by Janum Sethi

Doctor of Philosophy in Philosophy

University of California, Berkeley

Professor Hannah Ginsborg, co-chair

Professor Daniel Warren, co-chair

With his ambitious argument in the Transcendental Deduction, Kant claims to have established that a certain purely formal self-consciousness -- the mere consciousness that my thoughts and judgments are mine -- guarantees the objectivity of those thoughts and judgments,that is, their claim to represent the world as it is. But this intended conclusion gives rise to two questions:

(1) If merely being conscious that my thoughts are mine guarantees their objectivity, does Kant mean to deny that I can ever be conscious of thoughts that are subjective?

(2) Does Kant's apparently exclusive focus on formal self-conscious-ness in the Deduction mean that this is the only way he thinks a cognitive subject can be conscious of herself?

Both questions can be seen as versions of a more general worry about whether a robust account of subjectivity is compatible with Kant's description of cognition in the first Critique. It is the project of my dissertation to argue that such an account of subjectivity is not only possible, but essential to Kant's analysis of cognition. Much of the existing secondary literature on the topic, I claim, overlooks the fact that the two questions I list above are related, and can be jointly answered.

To motivate such an answer, I argue against the standard interpretive response to (1), according to which a subject can judge in away that is `merely subjective' by expressing what is true from her particular spatiotemporal point of view rather than from every point of view. I argue that this suggestion misunderstands Kant's objective/subjective distinction: merely subjective judgments are not about the world at all, whereas judgments made from a spatiotemporal point of view surely are.

I also challenge the widely accepted response to (2), on which a subject can become conscious of herself by introspectively becoming aware of her representations as representations. Whereas this entails that empirical self-consciousness is incidental to -- and an interruption of -- object-directed cognitive activity, I argue that Kant strongly indicates that empirical self-consciousness is involved in and essential for carrying out such cognitive activity in the first place.

In light of these arguments, I develop an alternative account on which I respond to (1) by arguing that judgments count as `merely subjective' according to Kant insofar as they express combinations of thoughts that a subject finds herself having as a result of psychological associations that hold in her particular case. Furthermore, I claim,it is consciousness of such combinations that constitutes the empiricalself-consciousness discussed in (2). Such consciousness is necessary for cognition, I argue, because it explains how we first come to acquire new concepts.

Kant's claim that a subject's empirical character is as essential to he activity of cognition as her transcendental character finally amounts, on my view, to the familiar Kantian dictum that both receptivity and spontaneity are essential ingredients of cognition.