About

Dr. Jay Graham applies advanced epidemiologic methods and next-generation DNA sequencing to refine our understanding of the spatial and temporal transmission of antimicrobial resistance (AMR) and zoonotic infectious diseases. His research contributes to the development of more efficient and effective approaches to scale-up public health initiatives for the prevention and control of infectious diseases. He has worked in various countries across Latin America, Asia, and Africa, with extensive experience on the US-México border, where he conducted research on the primary prevention of diarrheal diseases and pneumonia within informal settlements of Ciudad Juárez, MX. Much of his recent work has focused on research to prevent and control the spread of antimicrobial resistance.

Research topics

• Computer Science
• Optics
• Artificial Intelligence
• Physics
• Astrophysics
• Programming language
• Computer graphics (images)
• Software engineering
• Algorithm
• Astronomy

Selected publications

• Lipopolysaccharide truncation and restoration drives a trade-off in resistance to two phages in <i>Pseudomonas aeruginosa</i>

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-01-20

  articleOpen access

  Abstract Phage therapy is a promising treatment for multidrug resistant bacterial infections, and for patients no longer able to tolerate antibiotic treatments. A major challenge for phage therapy is emergent phage resistance, which target bacteria acquire by structurally modifying or masking phage receptors to prevent adsorption. Functionally diverse phage cocktails that target a broad range of receptors are less prone to resistance as there is a higher fitness cost associated with modifying multiple receptors. Expanding phage libraries with well-characterised phages that target a broad range of receptors would aid in timely and strategic design of functionally diverse phage cocktails. Here, we aimed to isolate phages targeting novel receptors by enriching wastewater samples on a Pseudomonas aeruginosa PAO1 Δ pilA Δ galU unmarked deletion mutant lacking O-antigen, outer core lipopolysaccharide (LPS) and type IV pili (T4P) - the three most common Pseudomonas phage receptors. This led to the isolation of a novel phage, named Vale . Vale was predicted to bind the LPS inner core as it could only infect strains with truncated LPS, suggesting that the outer core LPS blocks Vale from accessing the inner core. We identified a trade-oM in resistance to Vale and another phage, Tor, that targets the LPS outer core, mediated by host-derived LPS modifications. The PAO1 host evolved resistance to Tor by 100-200kb genomic deletions, which resulted in LPS truncation and sensitivity to Vale. Complete LPS restoration in the Δ pilA Δ galU mutant conferred resistance to Vale and sensitivity to Tor in two out of three replicates. Combined treatment with Tor and Vale delayed the emergence of resistance in PAO1 for at least three times longer than individual phage treatments. This study provides an example of how using phage receptors to strategically design phage cocktails can minimise the likelihood of emergent phage resistance. Graphical abstract A summary of the LPS modifications, genomic mutations and phage susceptibilities of Tor and Vale resistant mutants. “Parent strain” refers to PAO1 Δ hsdR. Δ pilA Δ galU refers to PAO1 Δ hsdR Δ pilA Δ galU. The parent strain gains resistance to Tor via LPS truncation associated with 100-200 kb genomic deletions, resulting in sensitivity to Vale. Δ pilA Δ galU gains resistance to Vale by restoring its LPS, conferring sensitivity to Tor in two out of three repeats. As resistance to one phage sensitises bacteria to the other, combined treatment with both phages suppresses phage resistance for longer than individual treatments.

  PublisherOA PDFDOI

• HD 143811 AB b: A Directly Imaged Planet Orbiting a Spectroscopic Binary in Sco-Cen

  arXiv (Cornell University) · 2025-09-08

  preprintOpen access

  We present confirmation of HD 143811 AB b, a substellar companion to spectroscopic binary HD 143811 AB through direct imaging with the Gemini Planet Imager (GPI) and Keck NIRC2. HD 143811 AB was observed as a part of the Gemini Planet Imager Exoplanet Survey (GPIES) in 2016 and 2019 and is a member of the Sco-Cen star formation region. The exoplanet is detected $\sim 430$ mas from the host star by GPI. With two GPI epochs and one from Keck/NIRC2 in 2022, we confirm through common proper motion analysis that the object is bound to its host star. We derive an orbit with a semi-major axis of $64 ^{+32}_{-14}$ au and eccentricity ${0.23 ^{+0.24}_{-0.16}}$. Spectral analysis of the GPI $H$-band spectrum and NIRC2 \textit{L'} photometry provides additional proof that this object is a substellar companion. We compare the spectrum of HD 143811 AB b to PHOENIX stellar models and Exo-REM exoplanet atmosphere models and find that Exo-REM models provide the best fits to the data. From the Exo-REM models, we derive an effective temperature of $1042^{+178}_{-132}$ K for the planet and translate the derived luminosity of the planet to a mass of $5.6 \pm 1.1~M_\textrm{Jup}$ assuming hot-start evolutionary models. HD 143811 AB b is the first directly imaged planet around a binary that is not on an ultra-wide orbit. Future characterization of this object will shed light on the formation of planets around binary star systems.

  PublisherOA PDFDOI

• Characterization of the Host Binary of the Directly Imaged Exoplanet HD 143811 AB b

  ArXiv.org · 2025-09-08

  preprintOpen access

  HD~143811~AB is the host star to the directly imaged planet HD~143811~AB~b, which was recently discovered using data from the Gemini Planet Imager and Keck NIRC2. A member of the Sco-Cen star-forming region with an age of $13 \pm 4$ Myr, HD~143811~AB is somewhat rare among hosts of directly imaged planets as it is a close stellar binary, with an $\sim$18 day period. Accurate values for the orbital and stellar parameters of this binary are needed to understand the formation and evolutionary history of the planet in orbit. We utilize archival high-resolution spectroscopy from FEROS on the MPG/ESO 2.2-meter telescope to fit the orbit of the binary, and combine with unresolved photometry to derive the basic stellar properties of the system. From the orbit, we derive precise values of orbital period of $18.59098 \pm 0.00007$ days, and mass ratio of $0.885 \pm 0.003$. When combined with stellar evolutionary models, we find masses of both components of $M_A = 1.30^{+0.03}_{-0.05}$ M$_\odot$ and $M_B = 1.15^{+0.03}_{-0.04}$ M$_\odot$. While the current data are consistent with the planet and stellar orbits being coplanar, the 3D orientations of both systems are currently poorly constrained, with additional observations required to more rigorously test for coplanarity.

  PublisherOA PDFDOI

• HD 143811 AB b: A Directly Imaged Planet Orbiting a Spectroscopic Binary in Sco-Cen

  The Astrophysical Journal Letters · 2025-12-11 · 2 citations

  articleOpen accessCorresponding

  Abstract We present confirmation of HD 143811 AB b, a substellar companion to spectroscopic binary HD 143811 AB through direct imaging with the Gemini Planet Imager (GPI) and Keck NIRC2. HD 143811 AB was observed as a part of the GPI Exoplanet Survey in 2016 and 2019 and is a member of the Sco-Cen star formation region. The exoplanet is detected ∼430 mas from the host star by GPI. With two GPI epochs and one from Keck/NIRC2 in 2022, we confirm through common proper motion analysis that the object is bound to its host star. We derive an orbit with a semimajor axis of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>6</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>14</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>32</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> au and eccentricity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>0.23</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.16</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.24</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> . Spectral analysis of the GPI H -band spectrum and NIRC2 L′ photometry provides additional proof that this object is a substellar companion. We compare the spectrum of HD 143811 AB b to PHOENIX stellar models and Exo-Radioactive-Convective Equilibrium Model (REM) exoplanet atmosphere models and find that Exo-REM models provide the best fits to the data. From the Exo-REM models, we derive an effective temperature of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>104</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>132</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>178</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> K for the planet and translate the derived luminosity of the planet to a mass of 5.6 ± 1.1 M Jup assuming hot-start evolutionary models. HD 143811 AB b is the first directly imaged planet around a binary that is not on an ultrawide orbit. Future characterization of this object will shed light on the formation of planets around binary star systems.

  PublisherDOI

• Characterization of the Host Binary of the Directly Imaged Exoplanet HD 143811 AB b

  The Astrophysical Journal Letters · 2025-12-11 · 1 citations

  articleOpen accessCorresponding

  Abstract HD 143811 AB is the host star to the directly imaged planet HD 143811 AB b, which was recently discovered using data from the Gemini Planet Imager and Keck NIRC2. A member of the Sco-Cen star-forming region with an age of 13 ± 4 Myr, HD 143811 AB is somewhat rare among hosts of directly imaged planets, as it is a close stellar binary, with an ∼18-day period. Accurate values for the orbital and stellar parameters of this binary are needed to understand the formation and evolutionary history of the planet in orbit. We utilize archival high-resolution spectroscopy from FEROS on the MPG/ESO 2.2 m telescope to fit the orbit of the binary, and we combine with unresolved photometry to derive the basic stellar properties of the system. From the orbit, we derive precise values of orbital period of 18.59090 ± 0.00007 days and mass ratio of 0.886 ± 0.003. When combined with stellar evolutionary models, we find masses of both components of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>M</mml:mi> <mml:mi mathvariant="normal">A</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>1.3</mml:mn> <mml:msubsup> <mml:mn>0</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.05</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M ⊙ and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>M</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>1.1</mml:mn> <mml:msubsup> <mml:mn>5</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M ⊙ . While the current data are consistent with the planet and stellar orbits being coplanar, the 3D orientations of both systems are currently poorly constrained, with additional observations required to more rigorously test for coplanarity.

  PublisherDOI

• A Decade of Linear and Circular Polarimetry with the POLISH2 Polarimeter

  The Astrophysical Journal Supplement Series · 2023-02-01 · 7 citations

  articleOpen access

  Abstract The POLISH2 optical polarimeter has been in operation at the Lick Observatory 3 m Shane telescope since 2011, and it was commissioned at the Gemini North 8 m in 2016. This instrument primarily targets exoplanets, asteroids, and the Crab Pulsar, but it has also been used for a wide variety of planetary, galactic, and supernova science. POLISH2's photoelastic modulators, employed instead of rotating wave plates or ferroelectric liquid crystal modulators, offer the unprecedented ability to achieve sensitivity and accuracy of order 1 ppm (0.0001%), which are difficult to obtain with conventional polarimeters. Additionally, POLISH2 simultaneously measures the intensity (Stokes I ), linear polarization (Stokes Q and U ), and circular polarization (Stokes V ), which fully describe the polarization state of incident light. We document our laboratory and on-sky calibration methodology and our archival on-sky database, and we demonstrate the conclusive detection of circular polarization of certain objects.

  PublisherOA PDFDOI

• Zodiacal exoplanets in time (ZEIT) - II. A 'super-Earth' orbiting a young K dwarf in the Pleiades Neighbourhood

  UNC Libraries · 2023-07-21

  articleOpen access

  We describe a 'super-Earth'-size (2.30 ± 0.16 R⊕) planet transiting an early K-type dwarf star in the Campaign 4 field observed by the K2 mission. The host star, EPIC 210363145, was identified as a candidate member of the approximately 120 Myr-old Pleiades cluster based on its kinematics and photometric distance. It is rotationally variable and exhibits near-ultraviolet emission consistent with a Pleiades age, but its rotational period is ≈20 d and its spectrum contains no Ha emission nor the Li I absorption expected of Pleiades K dwarfs. Instead, the star is probably an interloper that is unaffiliated with the cluster, but younger (≲1.3 Gyr) than the typical field dwarf.We ruled out a false positive transit signal produced by confusion with a background eclipsing binary by adaptive optics imaging and a statistical calculation. Doppler radial velocity measurements limit the companion mass to &lt; 2 times that of Jupiter. Screening of the light curves of 1014 potential Pleiades candidate stars uncovered no additional planets. An injection-and-recovery experiment using the K2 Pleiades light curves with simulated planets, assuming a planet population like that in the Kepler prime field, predicts only 0.8- 1.8 detections (versus ~20 in an equivalent Kepler sample). The absence of Pleiades planet detections can be attributed to the much shorter monitoring time of K2 (80 d versus 4 yr), increased measurement noise due to spacecraft motion, and the intrinsic noisiness of the stars.

  PublisherDOI

• Testing the Interaction Between a Substellar Companion and a Debris Disk in the HR 2562 System

  arXiv (Cornell University) · 2023-02-09

  preprintOpen access

  The HR 2562 system is a rare case where a brown dwarf companion resides in a cleared inner hole of a debris disk, offering invaluable opportunities to study the dynamical interaction between a substellar companion and a dusty disk. We present the first ALMA observation of the system as well as the continued GPI monitoring of the companion's orbit with 6 new epochs from 2016 to 2018. We update the orbital fit and, in combination with absolute astrometry from GAIA, place a 3$σ$ upper limit of 18.5 $M_J$ on the companion's mass. To interpret the ALMA observations, we used radiative transfer modeling to determine the disk properties. We find that the disk is well resolved and nearly edge on. While the misalignment angle between the disk and the orbit is weakly constrained due to the short orbital arc available, the data strongly support a (near) coplanar geometry for the system. Furthermore, we find that the models that describe the ALMA data best have an inner radius that is close to the companion's semi-major axis. Including a posteriori knowledge of the system's SED further narrows the constraints on the disk's inner radius and place it at a location that is in reasonable agreement with, possibly interior to, predictions from existing dynamical models of disk truncation by an interior substellar companion. HR\,2562 has the potential over the next few years to become a new testbed for dynamical interaction between a debris disk and a substellar companion.

  PublisherOA PDFDOI

• CONCORDANCE OF REPEAT BIOPSY RESULTS AMONG EMBRYOS WITH 6 OR MORE ANEUPLOIDIES

  Fertility and Sterility · 2023-10-01 · 1 citations

  articleOpen access
  PublisherOA PDFDOI

• COMPARISON OF QUICK VERSUS TRADITIONAL WARMING PROTOCOLS POST-VITRIFICATION: CRYO-SURVIVAL &amp; FROZEN EMBRYO TRANSFER (FET) OUTCOMES

  Fertility and Sterility · 2023-10-01

  articleOpen accessSenior author
  PublisherOA PDFDOI

Recent grants

• Weighing the Most Massive Black Holes in the Local Universe

  NSF · $241k · 2010–2014

• Direct Detection & Characterization of Extra-Solar Planets

  NSF · $415k · 2009–2015

• Super Star Clusters in Starburst Galaxies

  NSF · $264k · 2002–2007

Frequent coauthors

• Paul Kalas

  302 shared

• Bruce Macintosh

  218 shared

• Gaspard Duchêne

  University of California, Berkeley

  206 shared

• Michael P. Fitzgerald

  University of California, Los Angeles

  181 shared

• Marshall D. Perrin

  Space Telescope Science Institute

  177 shared

• Christian Marois

  171 shared

• E. Nielsen

  149 shared

• Robert J. De Rosa

  University of California, Santa Barbara

  122 shared

Awards & honors

• AAAS Science & Technology Policy Fellow