Settling the Sample Complexity of Single-parameter Revenue Maximization

This paper settles the sample complexity of single-parameter revenue maximization by showing matching upper and lower bounds, up to a poly-logarithmic factor, for all families of value distributions that have been considered in the literature. The upper bounds are unified under a novel framework, which builds on the strong revenue monotonicity by Devanur, Huang, and Psomas (STOC 2016), and an information theoretic argument. This is fundamentally different from the previous approaches that rely on either constructing an $\epsilon$-net of the mechanism space, explicitly or implicitly via statistical learning theory, or learning an approximately accurate version of the virtual values. To our knowledge, it is the first time information theoretical arguments are used to show sample complexity upper bounds, instead of lower bounds. Our lower bounds are also unified under a meta construction of hard instances.Comment: 49 pages, Accepted by STOC1

A CF3I-based SDD Prototype for Spin-independent Dark Matter Searches

The application of Superheated Droplet Detectors (SDDs) to dark matter searches has so far been confined to the light nuclei refrigerants C2ClF5 and C4F10 (SIMPLE and PICASSO, respectively), with a principle sensitivity to spin-dependent interactions. Given the competitive results of these devices, as a result of their intrinsic insensitivity to backgrounds, we have developed a prototype trifluoroiodomethane (CF3I)-loaded SDD with increased sensitivity to spin-independent interactions as well. A low (0.102 kgd) exposure test operation of two high concentration, 1 liter devices is described, and the results compared with leading experiments in both spin-dependent and -independent sectors. Although competitive in both sectors when the difference in exposures is accounted for, a problem with fracturing of the detector gel must be addressed before significantly larger exposures can be envisioned.Comment: revised and updated; accepted Astrop. Phy

Alveolar Erosion and its Conservation Recommendations for the Sandstone Masonry at Durham Castle

This research addresses the sandstone masonry of Durham Castle, a World Heritage site located in Durham, England. The study encompasses a focus on its current condition, deterioration mechanisms, and in particular, alveolar erosion, and the performance of previous repair techniques. The stone and weathering observed at the castle appear to be consistent across the entire site, regardless of age or location and are representative of other buildings in the area. The obvious diagnosis therefore appears to be related to the geo-chemical nature of the stone more than any other single factor. Alveolar erosion is particularly evident and poses the greatest risk given its resultant loss of stone and unit volume, leading to visual disfigurement and structural instability. Because of this long-lived problem, composite mortar repairs and stone replacement have frequently been performed on the castle. This study researches this current deterioration mechanism through literature reviews, archival research, on-site survey and investigation, and material analysis including thin section petrography, soluble salt and clay identification, porosity, and water absorption/desorption. This study concludes with possible sources of alveolar erosion at Durham Castle and conservation recommendations to maximize the retention of original stone through both preventive and remedial treatments before replacement in kind becomes necessary

Acceleration, streamlines and potential flows in general relativity: analytical and numerical results

Analytical and numerical solutions for the integral curves of the velocity field (streamlines) of a steady-state flow of an ideal fluid with $p = \rho$ equation of state are presented. The streamlines associated with an accelerate black hole and a rigid sphere are studied in some detail, as well as, the velocity fields of a black hole and a rigid sphere in an external dipolar field (constant acceleration field). In the latter case the dipole field is produced by an axially symmetric halo or shell of matter. For each case the fluid density is studied using contour lines. We found that the presence of acceleration is detected by these contour lines. As far as we know this is the first time that the integral curves of the velocity field for accelerate objects and related spacetimes are studied in general relativity.Comment: RevTex, 14 pages, 7 eps figs, CQG to appea

untitled, unmastered.

From one writer to another: Writing is often a therapeutic release for me. Being able to encounter my own words, as well as the words of others, has helped form the contours of my thinking and my ability to name. When I write, I am able to describe my experiences and my truths, but these words alone cannot help me live my convictions. In this sense, as a writer, the act of writing fails me. When we write, we dis-embody our beliefs. That is, we must take our beliefs from our body and bind them to the page. No longer fluid and adaptable, but immutable symbols fixed in time. Symbols to be summoned upon when needed in the future—much like we summon upon our gadgets to tell us where to go. Many of us in the industrial world have lost our sense of direction and ability to navigate, preferring to surrender our spatial and geographic awareness to technology. We offload our sense of belonging, our sense of place, and, in doing so, we literally outsource our ancestral ability to read the land, the sea, the weather. Similarly, writing externalizes our innate and experiential sense of being and knowing. When we release words onto the page—without continuing to embody and practice—we lose our internal compass. Without care, writing creates windows of forgetting because we no longer need to live our beliefs. Our ancestors knew that the power of the word lives in the call, not the page. When we call out, we speak our life, our breath, into the life of another. In this exchange, our life energies blend and create a synergy of movements that give form to our collective futures. I submit this ‘blank’ page as an offering. May this blank page blanket us as we continue to breathe life in ways ink cannot capture. With love, simple an

Efficient information retrieval model: overcoming challenges in search engines-an overview

Search engines play a vital role in information retrieval (IR) indexing and processing vast and diverse data, which now encompasses the ever-expanding wealth of multimedia content. However, search engine performance relies on the efficiency and effectiveness of their information retrieval systems (IRS). To enhance search engine performance, there is a need to develop more efficient and accurate IRS that retrieves relevant information quickly and accurately. To address this challenge, various approaches, including inverted indexing, query expansion, and relevance feedback, have been proposed for IR. Although these approaches have shown promising results, but their effectiveness and limitations require a comprehensive examination This research aims to investigate the challenges and opportunities in designing an efficient IRS for search engines and identify key areas for improvement and future research. The study involves a comprehensive literature review on information retrieval impacting academia, industry, healthcare, e-commerce, and other domains. Researchers rely on search engines to access relevant scientific papers, professionals use them to gather market intelligence, and consumers utilize them for product research and decision-making. The findings of this study will contribute to the development of more efficient and effective information retrieval systems, leading to improved search engine performance and user satisfaction

RACE-BASED EXPERIENCES OF BLACK COLLEGE STUDENTS ATTENDING PREDOMINATELY WHITE INSTITUTIONS

The purpose of this study was to describe the raced-based experiences of Black students attending a predominately White institution. Data were collected through multiple sources, including informed consent, demographic surveys, and semi-structured interviews. The data collected in this study were analyzed using Moustakas’s (1994) Modification of the Van Kaam (1959, 1966) method for analyzing phenomenological data. The Modified Van Kaam method consists of seven steps for examining the completed transcription of the participant’s responses. A transcendental phenomenological approach was used in my study to explore the essence of the participants’ experiences that emerged from the audio-recorded semi-structured interview. Nine themes emerged from the data and identified the lived experiences of participants. The essence of the participant’s experiences in this study demonstrated a variety of ways Black college students were aware of their race prior to coming to college, and how each participant’s awareness of their race impacted their overall campus experience. Additionally, whether through first-hand experience, social media, or the vicarious experience of another Black student, race-based interactions were significant in altering how engaged and how safe Black college students felt while they were attending predominately White institutions. The results of this study indicated that the overall developmental process for Black college students is independent from the majority culture and must be further explored and supported. Specifically, future research should explore impact racial microaggressions have on Black students psychologically, and behaviorally on college campuses and within their campus community