Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Theses/Dissertations

Discipline
Institution
Keyword
Publication Year
Publication
File Type

Articles 1 - 30 of 57336

Full-Text Articles in Physical Sciences and Mathematics

Growth, Lipid Production And Biodiesel Potential Of Chromulina Freiburgensis Dofl., An Acidophilic Chrysophyte Isolated From Berkeley Pit Lake, June E. Mohler Mitman Mar 2109

Growth, Lipid Production And Biodiesel Potential Of Chromulina Freiburgensis Dofl., An Acidophilic Chrysophyte Isolated From Berkeley Pit Lake, June E. Mohler Mitman

Graduate Theses & Non-Theses

Microalgae remain a promising, but underdeveloped source of lipids for sustainable biodiesel. Some of the obstacles to cost-effective commercial-scale production have been culture contamination and expensive harvest methods. A chrysophyte isolated from Berkeley Pit Lake and identified as Chromulina freiburgensis, was found to grow rapidly in a pH 2.5 liquid medium and to amass numerous intracellular lipid bodies. This research addresses the scarcity of published knowledge on the topic of chrysophyte species as potential lipid sources for biodiesel. It investigates how growth phase, culture conditions, and harvest timing influence the quantity and composition of lipids produced by this alga ...


Exposing And Fixing Causes Of Inconsistency And Nondeterminism In Clustering Implementations, Xin Yin Dec 2021

Exposing And Fixing Causes Of Inconsistency And Nondeterminism In Clustering Implementations, Xin Yin

Dissertations

Cluster analysis aka Clustering is used in myriad applications, including high-stakes domains, by millions of users. Clustering users should be able to assume that clustering implementations are correct, reliable, and for a given algorithm, interchangeable. Based on observations in a wide-range of real-world clustering implementations, this dissertation challenges the aforementioned assumptions.This dissertation introduces an approach named SmokeOut that uses differential clustering to show that clustering implementations suffer from nondeterminism and inconsistency: on a given input dataset and using a given clustering algorithm, clustering outcomes and accuracy vary widely between (1) successive runs of the same toolkit, i.e., nondeterminism ...


The Food Truck Problem, Supply Chains And Extensions Of The Newsvendor Problem, Dennis Quayesam Aug 2021

The Food Truck Problem, Supply Chains And Extensions Of The Newsvendor Problem, Dennis Quayesam

Electronic Theses and Dissertations

Inventory control is important to ensuring sufficient quantities of items are available tomeet demands of customers. The Newsvendor problem is a model used in Operations Research to determine optimal inventory levels for fulfilling future demands. Our study extends the newsvendor problem to a food truck problem. We used simulation to show that the food truck does not reduce to a newsvendor problem if demand depends on exogenous factors such temperature, time etc. We formulate the food truck problem as a multi-product multi-period linear program and found the dual for a single item. We use Discrete Event Simulation to solve the ...


Logbert: Log Anomaly Detection Via Bert, Haixuan Guo Aug 2021

Logbert: Log Anomaly Detection Via Bert, Haixuan Guo

All Graduate Theses and Dissertations

When systems break down, administrators usually check the produced logs to diagnose the failures. Nowadays, systems grow larger and more complicated. It is labor-intensive to manually detect abnormal behaviors in logs. Therefore, it is necessary to develop an automated anomaly detection on system logs. Automated anomaly detection not only identifies malicious patterns promptly but also requires no prior domain knowledge. Many existing log anomaly detection approaches apply natural language models such as Recurrent Neural Network (RNN) to log analysis since both are based on sequential data. The proposed model, LogBERT, a BERT-based neural network, can capture the contextual information in ...


On-Chip Nanoscale Plasmonic Optical Modulators, Abdalrahman Mohamed Nader Abdelhamid Jun 2021

On-Chip Nanoscale Plasmonic Optical Modulators, Abdalrahman Mohamed Nader Abdelhamid

Theses and Dissertations

In this thesis work, techniques for downsizing Optical modulators to nanoscale for the purpose of utilization in on chip communication and sensing applications are explored. Nanoscale optical interconnects can solve the electronics speed limiting transmission lines, in addition to decrease the electronic chips heat dissipation. A major obstacle in the path of achieving this goal is to build optical modulators, which transforms data from the electrical form to the optical form, in a size comparable to the size of the electronics components, while also having low insertion loss, high extinction ratio and bandwidth. Also, lap-on-chip applications used for fast diagnostics ...


Mechanistic And Synthetic Studies Of Oxidopyrylium Cycloaddition Reactions, Lauren P. Bejcek Jun 2021

Mechanistic And Synthetic Studies Of Oxidopyrylium Cycloaddition Reactions, Lauren P. Bejcek

Dissertations, Theses, and Capstone Projects

Cycloaddition chemistry has historically served as a robust route to stereo-rich and highly functionalized cyclic and heterocyclic compounds. Herein we describe our examination of 3-hydroxy-4-pyrone-derived oxidopyrylium cycloadditions in both mechanistic considerations as well as the unique synthetic advancements of their corresponding cycloadducts. Chapter 1 is a literature review where we specifically outline the use of oxidopyrylium cycloadditions in the synthesis of natural products. This includes the mention of previous syntheses prior to 2008, and a more thorough examination of the natural products synthesized from 2008 to present. The work exploits this chemistry as a facile route to highly complex 7-membered ...


Learn Biologically Meaningful Representation With Transfer Learning, Di He Jun 2021

Learn Biologically Meaningful Representation With Transfer Learning, Di He

Dissertations, Theses, and Capstone Projects

Machine learning has made significant contributions to bioinformatics and computational biol­ogy. In particular, supervised learning approaches have been widely used in solving problems such as bio­marker identification, drug response prediction, and so on. However, because of the limited availability of comprehensively labeled and clean data, constructing predictive models in super­ vised settings is not always desirable or possible, especially when using data­hunger, red­hot learning paradigms such as deep learning methods. Hence, there are urgent needs to develop new approaches that could leverage more readily available unlabeled data in driving successful machine learning ap­ plications in this ...


Synthetic And Biological Studies On Benzazepine Derivatives As Dopamine Receptor Ligands, Rajan Giri Jun 2021

Synthetic And Biological Studies On Benzazepine Derivatives As Dopamine Receptor Ligands, Rajan Giri

Dissertations, Theses, and Capstone Projects

Dopamine (DA) receptors, members of the G-protein coupled receptors (GPCRs) family, are divided in two groups based on their transmembrane structural homology domains: D1R-like (D1R, D5R sub-types) and D2R-like DA receptors (D2R, D3R and D4R sub-types). Disturbances in dopaminergic neurotransmission are associated with several CNS disorders. Hence, DA receptor selective ligands have been sought as pharmacological agents to normalize perturbations in the dopaminergic system. Despite several notable efforts, the discovery of highly selective ligands for dopamine receptor sub-types has proved challenging due to close transmembrane structural similarity, especially between DA receptor sub-types within the same group.

The 1-phenylbenzazepine scaffold is ...


Emergent Photophyiscs In Diketopyrrolopyrrole Superstructures, Andrew Levine Jun 2021

Emergent Photophyiscs In Diketopyrrolopyrrole Superstructures, Andrew Levine

Dissertations, Theses, and Capstone Projects

Organic semiconductors have received substantial attention as active components in optoelectronic devices because of their processability and customizable electronic properties. Tailoring the organic active layer in these devices to exhibit desirable optoelectronic properties requires understanding the complex and often subtle structure-property relationships governing their photophysical response to light. Both structural organization and frontier molecular orbitals (FMO) play pivotal roles in energy relaxation processes, and complex interplay between organization and orbital energies are difficult to anticipate based upon the molecular structure of the components alone, especially in systems comprised of multiple components. In pursuit of design rules, there is a need ...


Skyrmions And Biskyrmions In Magnetic Films, Daniel Capic Jun 2021

Skyrmions And Biskyrmions In Magnetic Films, Daniel Capic

Dissertations, Theses, and Capstone Projects

Skyrmions have garnered significant attention in condensed matter systems in recent years. In principle, they are topologically protected, so there is a large energy barrier preventing their annihilation. Furthermore, they can exist at the nanoscale, be manipulated with very small currents, and be created by a number of different methods. This makes them attractive for use in potential computing applications. This work studies ferromagnetic skyrmions. In particular, it highlights our small contributions to the field of skyrmions in condensed matter systems, specifically in thin-film ferromagnets.


Development Of A Diamond Defect Quantum Sensing Platform For Probing Novel Quantum Magnetic Phases, Jeffrey Ahlers May 2021

Development Of A Diamond Defect Quantum Sensing Platform For Probing Novel Quantum Magnetic Phases, Jeffrey Ahlers

Senior Honors Papers / Undergraduate Theses

Nitrogen vacancy centers in diamond are highly effective quantum sensors due to their high spatial resolution and high magnetic field sensitivity. We present the construction of an optically detected magnetic resonance platform in order to facilitate the probing of magnetic phases in two-dimensional heterostructures. This includes the characterization of the required microwave voltage controlled oscillator and amplifier. In the presence of crystal strain, we measure ensemble nitrogen vacancy spin transitions with and without an applied magnetic field, and observe frequency shifts consistent with sample heating.


Theranostic Applications Of Sirna Bioconjugates In Cancer Detection And Treatment, Sunil S. Shah May 2021

Theranostic Applications Of Sirna Bioconjugates In Cancer Detection And Treatment, Sunil S. Shah

Seton Hall University Dissertations and Theses (ETDs)

Abstract

The emerging field of RNA nanotechnology has led to rapid advances in the applications of RNA in chemical biology, medicinal chemistry, and biotechnology. At the forefront of its utility is the ability to self-assemble multiple siRNAs into nanostructure formulations capable of targeting selected oncogenes and potentiating the gene therapy of malignant tumors. Self-assembled siRNA integrates multiple siRNAs within a single molecular platform for silencing multiple oncogenic mRNA targets with high precision and efficacy to potentially induce cancer cell apoptosis through the RNA interference (RNAi) pathway. Furthermore, the conjugation of siRNA self-assemblies with bio-active probes results in multi-functional theranostic (therapy ...


High-Order Flexible Multirate Integrators For Multiphysics Applications, Rujeko Chinomona May 2021

High-Order Flexible Multirate Integrators For Multiphysics Applications, Rujeko Chinomona

Mathematics Theses and Dissertations

Traditionally, time integration methods within multiphysics simulations have been chosen to cater to the most restrictive dynamics, sometimes at a great computational cost. Multirate integrators accurately and efficiently solve systems of ordinary differential equations that exhibit different time scales using two or more time steps. In this thesis, we explore three classes of time integrators that can be classified as one-step multi-stage multirate methods for which the slow dynamics are evolved using a traditional one step scheme and the fast dynamics are solved through a sequence of modified initial value problems. Practically, the fast dynamics are subcycled using a small ...


Spectral Ground Motion Characteristics Of Induced Earthquakes In The Fort Worth Basin, Texas, Seongju Jeong May 2021

Spectral Ground Motion Characteristics Of Induced Earthquakes In The Fort Worth Basin, Texas, Seongju Jeong

Earth Sciences Theses and Dissertations

Concurrent with the development of unconventional oil and gas production, seismicity in the central United States has dramatically increased. Previous studies in many locations suggest that the earthquakes reactivate pre-existing faults, as a result of changing subsurface stresses due to injection of fluids from wastewater disposal wells. This sudden rise in seismicity rate motivates an assessment and possible mitigation of seismic hazard due to the proximity of induced seismicity to metropolitan areas like the Dallas-Fort Worth, Texas.

Successful assessment and mitigation of earthquake hazards requires estimates of ground motion parameters representing path attenuation, site effects and source characteristics constrained by ...


Cu-Promoted C-H Bond Hydroxylation Inspired By Cu-Dependent Metalloenzymes, Rachel Trammell May 2021

Cu-Promoted C-H Bond Hydroxylation Inspired By Cu-Dependent Metalloenzymes, Rachel Trammell

Chemistry Theses and Dissertations

From 2003 to 2015, Schӧnecker and Baran proposed a dinuclear Cu/O2 species in their mechanistic proposal for the hydroxylation of sp3 C-H bonds within their systems (proposed based on yields). Inspired from the site selectivity of this methodology and poor analysis of the mechanism, the first project was inspired to re-examine the sp3 C-H bond hydroxylation by Schrӧnecker and Baran and perform an intensive investigation into understanding how Cu/O2 interact which led us to propose a new mechanism based on the evidence collected (i.e., LCuII-hydroperoxide species that undergoes homolytic O-O bond ...


Enhancing Infrasonic Signal Detection And Event Localization Through Advanced Computational Methods, Fransiska Dannemann Dugick May 2021

Enhancing Infrasonic Signal Detection And Event Localization Through Advanced Computational Methods, Fransiska Dannemann Dugick

Earth Sciences Theses and Dissertations

The installation of worldwide infrasound and seismo-acoustic networks at both global and regional scales necessitates automated techniques and algorithms for accurate and efficient data processing and analysis. Signals recorded across the networks originate from a number of natural and anthropogenic sources. Data processing efforts focus on the separation of signals of interest from background noise, followed by the identification, or detection of signals of interest. Once signals are identified, association and location processing produces estimates of a signal's source. This dissertation focuses on the evaluation of automated processes for identifying and locating sources of interest.

Chapter two applies two ...


Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu May 2021

Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu

Earth Sciences Theses and Dissertations

Landsides are a natural geomorphic process yet a dangerous hazard which annually causes thousands of casualties and billions of property loss in a global scale. Understanding landslide motion kinematics from early initiation to final deposition is critical for monitoring, assessing, and forecasting landslide movement in order to mitigate their hazards. Landslides occur under diverse environmental settings and appear in variable types; however, all types of landslides can be mechanically attributed to shearing failure at the basal surface due to stress regime shift contributed by internal and/or external forcing. Typical internal factors include soil/rock weathering, whereas typical external triggering ...


Farm To Boardroom: How Improving Farm Conditions Leads To Sustained And Ethical Profit, Emily Mueller May 2021

Farm To Boardroom: How Improving Farm Conditions Leads To Sustained And Ethical Profit, Emily Mueller

Student Theses 2015-Present

As a society evolving and innovating at a pace faster than ever before seen in human history, we find ourselves at a crossroads of dealing with planetary boundaries and improving social standards. We are met with a crisis just thirty years away; the crisis of needing to be able to effectively and sustainably feed ten billion people across the globe. The 20th century brought on a booming age for industrializing the food system in order to increase yield and thus profit. The new process was a significant breakthrough at its time, but now we must face the question of when ...


Musical Gesture Through The Human Computer Interface: An Investigation Using Information Theory, Michael Vincent Blandino May 2021

Musical Gesture Through The Human Computer Interface: An Investigation Using Information Theory, Michael Vincent Blandino

LSU Doctoral Dissertations

This study applies information theory to investigate human ability to communicate using continuous control sensors with a particular focus on informing the design of digital musical instruments. There is an active practice of building and evaluating such instruments, for instance, in the New Interfaces for Musical Expression (NIME) conference community. The fidelity of the instruments can depend on the included sensors, and although much anecdotal evidence and craft experience informs the use of these sensors, relatively little is known about the ability of humans to control them accurately. This dissertation addresses this issue and related concerns, including continuous control performance ...


Explorations Of Thermus Thermophilus Hb8 Transcription Factors Ttha1437 And Ttha1719 Using The Combinatorial Selection Method Repsa, Sarah Claire Sneed May 2021

Explorations Of Thermus Thermophilus Hb8 Transcription Factors Ttha1437 And Ttha1719 Using The Combinatorial Selection Method Repsa, Sarah Claire Sneed

Master of Science in Chemical Sciences Theses

In all organisms, genes exist that encode for regulatory proteins, called transcription factors (TFs) that can activate or repress transcription of specific genes depending on their biological function. Thermus thermophilus HB8 is speculated to contain 2,245 genes, of which 70 are postulated to be transcription factors. However, but for very few, little is known regarding the genes they regulate and their biological functions. The novel combinatorial method Restriction Endonuclease Protection, Selection, and Amplification (REPSA) has been successful for identifying and validating consensus binding sequences in T. thermophilus HB8 with previously studied TFs. Here REPSA was explored as a technique ...


Designing A Reactive Warhead To Bind And Inhibit Pseudomonas Aeruginosa’S Periplasmic Protein, Inhibitor Of Vertebrate Lysozyme, Leah Greinke May 2021

Designing A Reactive Warhead To Bind And Inhibit Pseudomonas Aeruginosa’S Periplasmic Protein, Inhibitor Of Vertebrate Lysozyme, Leah Greinke

Master of Science in Chemical Sciences Theses

Pseudomonas aeruginosa is a Gram-negative bacterium commonly found throughout the environment. It is a significant cause of disease and mortality in immunodeficient patients such as those suffering from cystic fibrosis (CF). Due to the emerging antibiotic resistance of P. aeruginosa, it is becoming increasingly more challenging to treat an infection by traditional means. Further complicating treatment, P. aeruginosa secretes a protein known as Inhibitor of Vertebrate Lysozyme (PaIVY) that binds to and inhibits C-type lysozyme, thus preventing the degradation of the bacterium. A reactive chemical warhead was synthesized from a rhenium(I) tricarbonyl derivative inorder to bind to and irreversibly ...


The Social Market Economy As A Formula For Peace, Prosperity, And Sustainability, Almuth D. Merkel May 2021

The Social Market Economy As A Formula For Peace, Prosperity, And Sustainability, Almuth D. Merkel

Doctor of International Conflict Management Dissertations

The social market economy was developed in Germany during the interwar period amidst political and economic turmoil. With clear demarcation lines differentiating it from socialism and laissez-faire capitalism, the social market economy became a formula for peace and prosperity for post WWII Germany. Since then, the success of the social market economy has inspired many other countries to adopt its principles. Drawing on evidence from economic history and the history of economic thought, this thesis first reviews the evolution of the fundamental principles that form the foundation of social-market economic thought. Blending the micro-economic utility maximization framework with traditional growth ...


Airbnb Price Prediction With Sentiment Classification, Peilu Liu May 2021

Airbnb Price Prediction With Sentiment Classification, Peilu Liu

Master's Projects

Airbnb is an online platform that provides arrangements for short-term local home renting services. It is a challenging task for the house owner to price a rental home and attract customers. Customers also need to evaluate the price of the rental property based on the listing details. This paper demonstrates several existing Airbnb price prediction models using machine learning and external data to improve the prediction accuracy. It also discusses machine learning and neural network models that are commonly used for price prediction. The goal of this paper is to build a price prediction model using machine learning and sentiment ...


Initial Investigation Of Wildflower Honey Using Headspace Solid-Phase Microextraction Coupled With Gas Chromatography-Mass Spectrometry For Geographical Information, Tyra Countiss May 2021

Initial Investigation Of Wildflower Honey Using Headspace Solid-Phase Microextraction Coupled With Gas Chromatography-Mass Spectrometry For Geographical Information, Tyra Countiss

Honors Theses

Honey has been used as a food, sugar substitute, and flavor enhancer forever. The uses for honey are extremely varied from food to medicine. It is widely touted that you can address seasonal allergies, especially those following a move, by eating local honey. For this to be true the composition of the local honey, including trapped pollen, would allow allergy symptoms to be eliminated. In this project, the volatile and semi-volatile aroma compounds in wild flower honey from several different locations were analyzed. Headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to help develop the ...


One-Pot Synthesis Of Disubstituted Primary Amines From Nitriles Via Grignard Addition And Metal-Alcohol Reduction, Joshua Peltan May 2021

One-Pot Synthesis Of Disubstituted Primary Amines From Nitriles Via Grignard Addition And Metal-Alcohol Reduction, Joshua Peltan

Honors Theses

The process of developing a working base case procedure for a novel one-pot-two-step synthesis of primary amines from Grignard reagents, nitriles, sodium metal or alkali metal loaded silica gel, and alcohol is described. Initial steps towards applying the process broadly are detailed. The process has the potential to be an affordable, convenient, safer, greener, and more accessible alternative to exiting methods of accomplishing the same transformation. The reaction scheme has been proven to provide yields and purity comparable to existing methods for certain pairs of substrates; however, its utility as a general-purpose method for transforming arbitrary pairs of Grignard reagent ...


Suzuki Coupling Catalyzed By (8-(Dimesitylboryl)Quinoline)Palladium(0) Species: A Theoretical Analysis, Haley S. Rust May 2021

Suzuki Coupling Catalyzed By (8-(Dimesitylboryl)Quinoline)Palladium(0) Species: A Theoretical Analysis, Haley S. Rust

Honors Thesis

The Suzuki reaction is a catalyzed cross-coupling reaction which is of upmost importance in the formation of carbon-carbon (C-C) bonds in modern organic synthesis. Recently a new catalyst including an 8-(dimesitylboryl)quinoline for the coupling of aryl halides with phenylboronic acids was synthetized. We synthesized ligand that includes a frustrated Lewis pair, (quinolin-8-yl)dimesitylborane (DMBQ), complexed it with group X metals (nickel (Ni), palladium (Pd), and platinum (Pt)), and studied the process of oxidative addition with carbon-fluorine (C-F) bonds and activation towards Suzuki coupling. Mayer bond analysis and electron localization function maps showed a bond between the boron center ...


Lexicographic Sensitivity Functions For Nonsmooth Models In Mathematical Biology, Matthew D. Ackley May 2021

Lexicographic Sensitivity Functions For Nonsmooth Models In Mathematical Biology, Matthew D. Ackley

Electronic Theses and Dissertations

Systems of ordinary differential equations (ODEs) may be used to model a wide variety of real-world phenomena in biology and engineering. Classical sensitivity theory is well-established and concerns itself with quantifying the responsiveness of such models to changes in parameter values. By performing a sensitivity analysis, a variety of insights can be gained into a model (and hence, the real-world system that it represents); in particular, the information gained can uncover a system's most important aspects, for use in design, control or optimization of the system. However, while the results of such analysis are desirable, the approach that classical ...


Streaming Down The Stern-Brocot Tree: Finding And Expressing Solutions To Pell's Equation In Sl(2,Z), Marcus L. Shell May 2021

Streaming Down The Stern-Brocot Tree: Finding And Expressing Solutions To Pell's Equation In Sl(2,Z), Marcus L. Shell

Theses

This paper explores and elaborates on a method of solving Pell’s equation as introduced by Norman Wildberger. In the first chapters of the paper, foundational topics are introduced in expository style including an explanation of Pell’s equation. An explanation of continued fractions and their ability to express quadratic irrationals is provided as well as a connection to the Stern-Brocot tree and a convenient means of representation for each in terms of 2×2 matrices with integer elements. This representation will provide a useful way of navigating the Stern-Brocot tree computationally and permit us a means of computing continued ...


Benchmarking Clustering And Classification Tasks Using K-Means, Fuzzy C-Means And Feedforward Neural Networks Optimized By Pso, Adam Pickens, Adam Pickens May 2021

Benchmarking Clustering And Classification Tasks Using K-Means, Fuzzy C-Means And Feedforward Neural Networks Optimized By Pso, Adam Pickens, Adam Pickens

Honors College Theses

Clustering is a widely used unsupervised learning technique across data mining and machine learning applications and finds frequent use in diverse fields ranging from astronomy, medical imaging, search and optimization, geology, geophysics and sentiment analysis to name a few. It is therefore important to verify the effectiveness of the clustering algorithms in question and to make reasonably strong arguments for the acceptance of the end results generated by the validity indices that measure the compactness and separability of clusters. This work aims to explore the successes and limitations of popular clustering mechanisms such as K-Means and Fuzzy C-Means by comparing ...


Terrestrial Soldier Crab (Coenobita Clypeatus, Fabricius 1787) And Cerion Spp. (Röding 1798) Shell Relationship On San Salvador Island, Bahamas, Harley Hunt May 2021

Terrestrial Soldier Crab (Coenobita Clypeatus, Fabricius 1787) And Cerion Spp. (Röding 1798) Shell Relationship On San Salvador Island, Bahamas, Harley Hunt

Biology Theses

The Caribbean terrestrial soldier crab, Coenobita clypeatus(Fabricius 1787), coexist and utilize the shells of numerous species of land and marine gastropods. Soldier crabs rely on gastropod shells for protection as the crabs have a soft abdomen, leaving them vulnerable for predation and desiccation, threatening their survival. This creates a strong pressure to obtain well-fitting shells that provide adequate protection against water loss. Cerion of Röding (1798) shells are one of the most commonly used shells among living colonies of C. clypeatuson San Salvador Island. This study is interested in the frequency of shell use by C. clypeatus crabs ...