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Background Indeterminate focal liver observations in patients at risk for hepatocellular carcinoma (HCC) may require invasive biopsy or follow-up, which could lead to delays in definitive categorization and to postponement of treatment. Purpose To examine clinical effect of contrast-enhanced US (CEUS) in participants with high-risk indeterminate liver observations categorized as Liver Imaging Reporting and Data System (LI-RADS) category LR-4 (probably HCC) or LI-RADS category LR-M (probably or definitely malignant but not HCC specific) at CT or MRI. Materials and Methods This was a secondary analysis of a prospective international multicenter validation study for CEUS LI-RADS (January 2018 to August 2021). CEUS was performed within 4 weeks of CT or MRI. Tissue histologic and CT or MRI follow-up data were used as reference standards. Clinical effect of CEUS for HCC was evaluated in observations 10 mm or larger categorized as CT/MRI LR-4 and LR-M. Results Included were 109 participants (mean age, 64.3 years ± 8.3 [SD]; 68.8% [75 of 109] male participants) with 113 observations (≥10 mm) categorized as CT/MRI LR-4 (53.1%; 60 of 113) or LR-M (46.9%; 53 of 113). CEUS resulted in management recommendation changes in 33.6% (95% CI: 25, 43; 38 of 113) of observations; among these, 95% (95% CI: 82, 99; 36 of 38) were correct. A total of 30.1% (34 of 113) of CT/MRI LR-4 and LR-M observations were categorized at CEUS as LI-RADS category LR-5 (definite HCC), making biopsy unnecessary; 94% (32 of 34) of these categorizations were correct. Of CT/MRI LR-4 observations, 7% (four of 60) were categorized as CEUS LR-M; subsequent biopsy confirmed non-HCC malignancy in all participants. Clinical impact of CEUS was more substantial for observations 20 mm or larger ( n = 68); CEUS helped appropriately categorize both LR-5 and LR-M lesions as HCC and non-HCC malignancies, respectively, and resulted in management recommendation changes in 40% (27 of 68) of observations with 100% accuracy. Conclusion CEUS resolved some high-risk indeterminate liver observations (categorized as LR-4 and LR-M at CT or MRI), with particularly high clinical impact for observations measuring at least 20 mm. Clinical trial registration no. NCT03318380 © RSNA, 2025 Supplemental material is available for this article.

Background & Aims: Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Liver transplantation (LT) is a curative treatment option. We investigated survival outcomes based on recipient-donor sex constellation (RDSC) following LT., Methods: We performed a European Liver Transplant Registry analysis, including patients from 1988 to December 2022. The cohort was split into four RDSC groups: female donor female recipient (FDFR), female donor male recipient (FDMR), male donor female recipient (MDFR) and male donor male recipient (MDMR). Survival analysis, including death with recurrence, was performed., Results: In 7601 LT for HCC with an overall median follow-up of 22.6 months (5.8, 60.7), death was registered in 25.1% and, as primary cause of death, HCC tumour recurrence in 26.0%. There was no statistically significant difference on crude survival estimates among the different RDSC groups (log-rank p = 0.66) with 10-year overall survival (OS) of 54.5% in FDFR, 54.6% in FDMR, 59.1% in MDFR and 56.9% in MDMR. On multivariable analysis, RDSC showed a significant effect on OS (FDFR as reference): MDFR (aHR 0.72, p = 0.023). No significant difference was found for FDMR (aHR 0.98, p = 0.821) and MDMR (aHR 0.90, p= 0.288). Regarding overall registered causes of death, differences between RDSC groups were found in rejection (p = 0.017) and cardiovascular (p = 0.046) associated deaths., Conclusions: In female recipients undergoing LT for HCC, male donor grafts were associated with a 28% reduction of mortality compared to female donor grafts., (© 2024 The Author(s). Liver International published by John Wiley & Sons Ltd.)

Background and Aim: Age and biological sex are risk factors for hepatocellular carcinoma (HCC) occurrence, but their impact on overall survival (OS) is a matter of debate. This study aims to investigate how sex and age at diagnosis, along with other associated factors (i.e., comorbidities, etiologies, therapy) impact OS in the HCC population. Method: Data from two HCC cohorts-a prospective registry from the University Hospital of Bern, Switzerland, and a retrospective registry from General Hospital Vienna, Austria-were combined and analyzed. Clinical and laboratory data were reviewed, and OS was compared using Kaplan-Meier curves and the log-rank test. Cox regression models with penalized splines were applied to examine how age at diagnosis influenced OS. Results: Of 1547 HCC patients, 1284 (84.1%) were male. Females were older (67 vs. 63 years, p < 0.001) and had lower rates of liver cirrhosis ( p < 0.001), cardiac comorbidities ( p < 0.001), and diabetes ( p < 0.001). No significant difference in median OS between men and women was observed (18 months vs. 16 months, p = 0.304). Mortality risk increased with age, particularly between 60 and 70 years. However, after adjusting for treatment, the age effect became non-significant ( p = 0.171). Conclusions: After controlling the model for therapy, neither age nor sex independently influenced OS in HCC patients, underscoring the impact of therapy on survival.

Background and Aims: The outcome of patients with HCC who achieved complete response (CR) to immune-checkpoint inhibitor (ICI)-based systemic therapies is unclear., Approach and Results: Retrospective study of patients with HCC who had CR according to modified Response Evaluation Criteria in Solid Tumors (CR-mRECIST) to ICI-based systemic therapies from 28 centers in Asia, Europe, and the United States. Of 3933 patients with HCC treated with ICI-based noncurative systemic therapies, 174 (4.4%) achieved CR-mRECIST, and 97 (2.5%) had CR according to RECISTv1.1 (CR-RECISTv1.1) as well. The mean age of the total cohort (male, 85%; Barcelona-Clinic Liver Cancer-C, 70%) was 65.9±9.8 years. The majority (83%) received ICI-based combination therapies. Median follow-up was 32.2 (95% CI: 29.9-34.4) months. One- and 3-year overall survival rates were 98% and 86%. One- and 3-year recurrence-free survival rates were excellent in patients with CR-mRECIST-only and CR-RECISTv1.1 (78% and 55%; 70% and 42%). Among patients who discontinued ICIs for reasons other than recurrence, those who received immunotherapy for ≥6 months after the first mRECIST CR had a longer recurrence-free survival than those who discontinued immunotherapy earlier (p=0.008). Of 9 patients who underwent curative surgical conversion therapy, 8 (89%) had pathological CR (CR-RECISTv1.1, n= 2/2; CR-mRECIST-only, n= 6/7)., Conclusions: Overall survival and recurrence-free survival of patients with CR-mRECIST-only and CR-RECISTv1.1 were excellent, and 6 of 7 patients with CR-mRECIST-only who underwent surgical conversion therapy had pathological CR. Despite potential limitations, these findings support the use of mRECIST in the context of immunotherapy for clinical decision-making. When considering ICI discontinuation, treatment for at least 6 months beyond CR seems advisable., (Copyright © 2024 American Association for the Study of Liver Diseases.)

Competing Interests: Competing interests: None declared.

Purpose: To determine the diagnostic accuracy of combining CEUS and CT/MRI LI-RADS major imaging features for the improved categorization of liver observations indeterminate on both CT/MRI and CEUS., Materials and Methods: A retrospective analysis using a database from a prospective study conducted at 11 centers in North America and Europe from 2018 to 2022 included a total of 109 participants at risk for HCC who had liver observations with indeterminate characterization (LR3, LR-4, and LR-M) on both CEUS and CT/MRI. The individual CEUS and CT/MRI LI-RADS major features were extracted from the original study and analyzed in various combinations. Reference standards included biopsy, explant histology, and follow-up CT/MRI. The diagnostic performance of the combinations of LI-RADS major features for definitive diagnosis of HCC was calculated. A reverse, stepwise logistical regression sub-analysis was also performed., Results: This study included 114 observations indeterminate on both CT/MRI and CEUS. These observations were categorized as LR-3 (n = 37), LR-4 (n = 41), and LR-M (n = 36) on CT/MRI and LR-3 (n = 48), LR-4 (n = 36), LR-M (n = 29), and LR-TIV (n = 1) on CEUS. Of them, 43.0% (49/114) were confirmed as HCC, 37.3% (43/114) non-malignant, and 19.3% (22/114) non-hepatocellular malignancies. The highest diagnostic accuracy among the combinations of imaging features was achieved in CT/MRI LR-3 observations, where the combination of CEUS arterial phase hyper-enhancement (APHE) + CT/MRI APHE had 96.7% specificity, 75.0% positive predictive value (PPV), and 86.5% accuracy for HCC., Conclusion: The combination of LI-RADS major features on CT/MRI and CEUS showed higher specificity, PPV, and accuracy compared to individual modalities' assessments, particularly for CT/MRI LR-3 observations., (© 2024. The Author(s).)

Introduction: The research field of artificial intelligence (AI) in medicine and especially in gastroenterology is rapidly progressing with the first AI tools entering routine clinical practice, for example, in colorectal cancer screening. Contrast-enhanced ultrasound (CEUS) is a highly reliable, low-risk, and low-cost diagnostic modality for the examination of the liver. However, doctors need many years of training and experience to master this technique and, despite all efforts to standardize CEUS, it is often believed to contain significant interrater variability. As has been shown for endoscopy, AI holds promise to support examiners at all training levels in their decision-making and efficiency., Methods: In this systematic review, we analyzed and compared original research studies applying AI methods to CEUS examinations of the liver published between January 2010 and February 2024. We performed a structured literature search on PubMed, Web of Science, and IEEE. Two independent reviewers screened the articles and subsequently extracted relevant methodological features, e.g., cohort size, validation process, machine learning algorithm used, and indicative performance measures from the included articles., Results: We included 41 studies with most applying AI methods for classification tasks related to focal liver lesions. These included distinguishing benign versus malignant or classifying the entity itself, while a few studies tried to classify tumor grading, microvascular invasion status, or response to transcatheter arterial chemoembolization directly from CEUS. Some articles tried to segment or detect focal liver lesions, while others aimed to predict survival and recurrence after ablation. The majority (25/41) of studies used hand-picked and/or annotated images as data input to their models. We observed mostly good to high reported model performances with accuracies ranging between 58.6% and 98.9%, while noticing a general lack of external validation., Conclusion: Even though multiple proof-of-concept studies for the application of AI methods to CEUS examinations of the liver exist and report high performance, more prospective, externally validated, and multicenter research is needed to bring such algorithms from desk to bedside., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

We develop a novel metal contact approach using an antimony (Sb)-platinum (Pt) bilayer to mitigate Fermi-level pinning in 2D transition metal dichalcogenide channels. This strategy allows for control over the transport polarity in monolayer WSe 2 devices. By adjustment of the Sb interfacial layer thickness from 10 to 30 nm, the effective work function of the contact/WSe 2 interface can be tuned from 4.42 eV (p-type) to 4.19 eV (n-type), enabling selectable n-/p-FET operation in enhancement mode. The shift in effective work function is linked to Sb-Se bond formation and an emerging n-doping effect. This work demonstrates high-performance n- and p-FETs with a single WSe 2 channel through Sb-Pt contact modulation. After oxide encapsulation, the maximum current density at |V D | = 1 V reaches 170 μA/μm for p-FET and 165 μA/μm for n-FET. This approach shows promise for cost-effective CMOS transistor applications using a single channel material and metal contact scheme.

Engineering atomic-scale defects has become an important strategy for the future application of transition metal dichalcogenide (TMD) materials in next-generation electronic technologies. Thus, providing an atomic understanding of the electron-defect interactions and supporting defect engineering development to improve carrier transport is crucial to future TMDs technologies. In this work, we utilize low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/S) to elicit how distinct types of defects bring forth scattering potential engineering based on intervalley quantum quasiparticle interference (QPI) in TMDs. Furthermore, quantifying the energy-dependent phase variation of the QPI standing wave reveals the detailed electron-defect interaction between the substitution-induced scattering potential and the carrier transport mechanism. By exploring the intrinsic electronic behavior of atomic-level defects to further understand how defects affect carrier transport in low-dimensional semiconductors, we offer potential technological applications that may contribute to the future expansion of TMDs.

In this article, a 0.7 nm thick monolayer MoS 2 nanosheet gate-all-around field effect transistors (NS-GAAFETs) with conformal high- κ metal gate deposition are demonstrated. The device with 40 nm channel length exhibits a high on-state current density of ~410 μ A μ m -1 with a large on/off ratio of 6 × 10 8 at drain voltage = 1 V. The extracted contact resistance is 0.48 ± 0.1 kΩ μ m in monolayer MoS 2 NS-GAAFETs, thereby showing the channel-dominated performance with the channel length scaling from 80 to 40 nm. The successful demonstration of device performance in this work verifies the integration potential of transition metal dichalcogenides for future logic transistor applications., (© 2024 IOP Publishing Ltd.)

Background and Aim: Treatment with sorafenib causes diverse side effects, which limits adherence. This work assesses whether Home Care, a psychosocial nursing intervention, prolongs the duration of treatment in patients with advanced hepatocellular carcinoma (HCC) and if it influences health-related quality of life (HRQL)., Methods and Results: This is a cohort study using data from patients receiving sorafenib in the prospective Bern HCC Cohort at the University Hospital. Duration of treatment, overall survival, and HRQL using the Functional Assessment of Cancer Therapy-Hepatobiliary questionnaire were compared in the two groups. A total of 173 patients were eligible for the analysis. Among them, 141 were in the Home Care program, and 32 were not. Patients with Home Care had a significantly longer duration of treatment (265 days vs 152 days, P  = 0.003) and a better functional well-being (17.7 vs 12.5, P  = 0.015)., Conclusion: Psychosocial interventions such as Home Care are a valid method in improving adherence to sorafenib and can therefore be recommended., (© 2021 The Authors. JGH Open published by Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Spin waves are excitations in ferromagnetic media that have been proposed as information carriers in hybrid spintronic devices with much lower operation power than conventional charge-based electronics. Their wave nature can be exploited in majority gates by using interference for computation. However, a scalable spin-wave majority gate that can be cointegrated alongside conventional electronics is still lacking. Here, we demonstrate a submicrometer inline spin-wave majority gate with fan-out. Time-resolved imaging of the magnetization dynamics by scanning transmission x-ray microscopy illustrates the device operation. All-electrical spin-wave spectroscopy further demonstrates majority gates with submicrometer dimensions, reconfigurable input and output ports, and frequency-division multiplexing. Challenges for hybrid spintronic computing systems based on spin-wave majority gates are discussed., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

The recent demonstration of ferroelectricity in ultrathin HfO 2 has kickstarted a new wave of research into this material. HfO 2 in the orthorhombic phase can be considered the first and only truly nanoscale ferroelectric material that is compatible with silicon-based nanoelectronics applications. In this article, we demonstrate the ferroelectric control of the magnetic properties of cobalt deposited on ultrathin aluminum-doped, atomic layer deposition-grown HfO 2 ( t HfO 2 = 6.5 nm). The ferroelectric effect is shown to control the shape of the magnetic hysteresis, quantified here by the magnetic switching energy. Furthermore, the magnetic properties such as the remanence are modulated by up to 41%. We show that this modulation does not only correlate with the charge accumulation at the interface but also shows an additional component associated with the ferroelectric polarization switching. An in-depth analysis using first order reversal curves shows that the coercive and interaction field distributions of cobalt can be modulated up to, respectively, 5.8% and 10.5% with the ferroelectric polarization reversal.

Atomically thin two-dimensional (2D) materials belonging to transition metal dichalcogenides, due to their physical and electrical properties, are an exceptional vector for the exploration of next-generation semiconductor devices. Among them, due to the possibility of ambipolar conduction, tungsten diselenide (WSe 2 ) provides a platform for the efficient implementation of polarity-controllable transistors. These transistors use an additional gate, named polarity gate, that, due to the electrostatic doping of the Schottky junctions, provides a device-level dynamic control of their polarity, that is, n- or p-type. Here, we experimentally demonstrate a complete doping-free standard cell library realized on WSe 2 without the use of either chemical or physical doping. We show a functionally complete family of complementary logic gates (INV, NAND, NOR, 2-input XOR, 3-input XOR, and MAJ) and, due to the reconfigurable capabilities of the single devices, achieve the realization of highly expressive logic gates, such as exclusive-OR (XOR) and majority (MAJ), with fewer transistors than possible in conventional complementary metal-oxide-semiconductor logic. Our work shows a path to enable doping-free low-power electronics on 2D semiconductors, going beyond the concept of unipolar physically doped devices, while suggesting a road to achieve higher computational densities in two-dimensional electronics.

The microwave dielectric properties of (Ba 0.1 Pb 0.9 )(Zr 0.52 Ti 0.48 )O 3 (BPZT) and ZnO thin films with thicknesses below were investigated. No significant dielectric relaxation was observed for both BPZT and ZnO up to 30 GHz. The intrinsic dielectric constant of BPZT was as high as 980 at 30 GHz. The absence of strong dielectric dispersion and loss peaks in the studied frequency range can be linked to the small grain diameters in these ultrathin films.

Directional antennas revolutionized modern day telecommunication by enabling precise beaming of radio and microwave signals with minimal loss of energy. Similarly, directional optical nanoantennas are expected to pave the way toward on-chip wireless communication and information processing. Currently, on-chip integration of such antennas is hampered by their multielement design or the requirement of complicated excitation schemes. Here, we experimentally demonstrate electrical driving of in-plane tunneling nanoantennas to achieve broadband unidirectional emission of light. Far-field interference, as a result of the spectral overlap between the dipolar emission of the tunnel junction and the fundamental quadrupole-like resonance of the nanoantenna, gives rise to a directional radiation pattern. By tuning this overlap using the applied voltage, we record directivities as high as 5 dB. In addition to electrical tunability, we also demonstrate passive tunability of the directivity using the antenna geometry. These fully configurable electrically driven nanoantennas provide a simple way to direct optical energy on-chip using an extremely small device footprint.

Direct exchange interaction allows spins to be magnetically ordered. Additionally, it can be an efficient manipulation pathway for low-powered spintronic logic devices. We present a novel logic scheme driven by exchange between two distinct regions in a composite magnetic layer containing a bistable canted magnetization configuration. By applying a magnetic field pulse to the input region, the magnetization state is propagated to the output via spin-to-spin interaction in which the output state is given by the magnetization orientation of the output region. The dependence of this scheme with input field conditions is extensively studied through a wide range of micromagnetic simulations. These results allow different logic operating modes to be extracted from the simulation results, and majority logic is successfully demonstrated.

Two-dimensional semiconducting materials of the transition-metal-dichalcogenide family, such as MoS 2 and WSe 2 , have been intensively investigated in the past few years, and are considered as viable candidates for next-generation electronic devices. In this paper, for the first time, we study scaling trends and evaluate the performances of polarity-controllable devices realized with undoped mono- and bi-layer 2D materials. Using ballistic self-consistent quantum simulations, it is shown that, with the suitable channel material, such polarity-controllable technology can scale down to 5 nm gate lengths, while showing performances comparable to the ones of unipolar, physically-doped 2D electronic devices.

Since the discovery of graphene, a broad range of two-dimensional (2D) materials has captured the attention of the scientific communities. Materials, such as hexagonal boron nitride (hBN) and the transition metal dichalcogenides (TMDs) family, have shown promising semiconducting and insulating properties that are very appealing for the semiconductor industry. Recently, the possibility of taking advantage of the properties of 2D-based heterostructures has been investigated for low-power nanoelectronic applications. In this work, we aim at evaluating the relation between the nature of the materials used in such heterostructures and the amplitude of the layer-to-layer charge transfer induced by an external electric field, as is typically present in nanoelectronic gated devices. A broad range of combinations of TMDs, graphene, and hBN has been investigated using density functional theory. Our results show that the electric field induced charge transfer strongly depends on the nature of the 2D materials used in the van der Waals heterostructures and to a lesser extent on the relative orientation of the materials in the structure. Our findings contribute to the building of the fundamental understanding required to engineer electrostatically the doping of 2D materials and to establish the factors that drive the charge transfer mechanisms in electron tunneling-based devices. These are key ingredients for the development of 2D-based nanoelectronic devices.

RF-sputtered thin films of spinel Li(x)Mg(1-2x)Al(2+x)O4 were investigated for use as solid electrolyte. The usage of this material can enable the fabrication of a lattice matched battery stack, which is predicted to lead to superior battery performance. Spinel Li(x)Mg(1-2x)Al(2+x)O4 thin films, with stoichiometry (x) ranging between 0 and 0.25, were formed after a crystallization anneal as shown by X-ray diffraction and transmission electron microscopy. The stoichiometry of the films was evaluated by elastic recoil detection and Rutherford backscattering and found to be slightly aluminum rich. The excellent electronic insulation properties were confirmed by both current-voltage measurements as well as by copper plating tests. The electrochemical stability window of the material was probed using cyclic voltammetry. Lithium plating and stripping was observed together with the formation of a Li-Pt alloy, indicating that Li-ions passed through the film. This observation contradicted with impedance measurements at open circuit potential, which showed no apparent Li-ion conductivity of the film. Impedance spectroscopy as a function of potential showed the occurrence of Li-ion intercalation into the Li(x)Mg(1-2x)Al(2+x)O4 layers. When incorporating Li-ions in the material the ionic conductivity can be increased by 3 orders of magnitude. Therefore it is anticipated that the response of Li(x)Mg(1-2x)Al(2+x)O4 is more adequate for a buffer layer than as the solid electrolyte.

Ultrathin LiMn2O4 electrode layers with average crystal size of ∼15 nm were fabricated by means of radio frequency sputtering. Cycling behavior and rate performance was evaluated by galvanostatic charge and discharge measurements. The thinnest films show the highest volumetric capacity and best cycling stability, retaining the initial capacity over 70 (dis)charging cycles when manganese dissolution is prevented. The increased stability for film thicknesses below 50 nm allows cycling in both the 4 and 3 V potential regions, resulting in a high volumetric capacity of 1.2 Ah/cm3. It is shown that the thinnest films can be charged to 75% of their full capacity within 18 s (200 C), the best rate performance reported for LiMn2O4. This is explained by the short diffusion lengths inherent to thin films and the absence of phase transformation.

Atomically-thin, inherently 2D semiconductors offer thickness scaling of nanoelectronic devices and excellent response to light for low-power versatile applications. Using small exfoliated flakes, advanced devices and integrated circuits have already been realized, showing great potential to impact nanoelectronics. Here, high-quality single-crystal MoSe2 is grown by molecular beam epitaxy on AlN(0001)/Si(111), showing the potential for scaling up growth to low-cost, large-area substrates for mass production. The MoSe2 layers are epitaxially aligned with the aluminum nitride (AlN) lattice, showing a uniform, smooth surface and interfaces with no reaction or intermixing, and with sufficiently high band offsets. High-quality single-layer MoSe2 is obtained, with a direct gap evidenced by angle-resolved photoemission spectroscopy and further confirmed by Raman and intense room temperature photoluminescence. The successful growth of high-quality MoSe2/Bi2Se3 multilayers on AlN shows promise for novel devices exploiting the non-trivial topological properties of Bi2Se3.

Two-terminal thin film VO2 devices show an abrupt decrease of resistance when the current or voltage applied exceeds a threshold value. This phenomenon is often described as a field-induced metal-insulator transition. We fabricate nano-scale devices with different electrode separations down to 100 nm and study how the dc switching voltage and current depend on device size and temperature. Our observations are consistent with a Joule heating mechanism governing the switching. Pulsed measurements show a switching time to the high resistance state of the order of one hundred nanoseconds, consistent with heat dissipation time. In spite of the Joule heating mechanism which is expected to induce device degradation, devices can be switched for more than 10(10) cycles making VO2 a promising material for nanoelectronic applications.

Quasi-particles with fractional charge and statistics, as well as modified Coulomb interactions, exist in a two-dimensional electron system in the fractional quantum Hall (FQH) regime. Theoretical models of the FQH state at filling fraction v = 5/2 make the further prediction that the wave function can encode the interchange of two quasi-particles, making this state relevant for topological quantum computing. We show that bias-dependent tunneling across a narrow constriction at v = 5/2 exhibits temperature scaling and, from fits to the theoretical scaling form, extract values for the effective charge and the interaction parameter of the quasi-particles. Ranges of values obtained are consistent with those predicted by certain models of the 5/2 state.

We demonstrate electrical control of the spin relaxation time T1 between Zeeman-split spin states of a single electron in a lateral quantum dot. We find that relaxation is mediated by the spin-orbit interaction, and by manipulating the orbital states of the dot using gate voltages we vary the relaxation rate W identical withT1(-1) by over an order of magnitude. The dependence of W on orbital confinement agrees with theoretical predictions, and from these data we extract the spin-orbit length. We also measure the dependence of W on the magnetic field and demonstrate that spin-orbit mediated coupling to phonons is the dominant relaxation mechanism down to 1 T, where T1 exceeds 1 s.

We present measurements of the rates for an electron to tunnel on and off a quantum dot, obtained using a quantum point contact charge sensor. The tunnel rates show exponential dependence on drain-source bias and plunger gate voltages. The tunneling process is shown to be elastic, and a model describing tunneling in terms of the dot energy relative to the height of the tunnel barrier quantitatively describes the measurements.