Alignment Shifts Research Articles

Enhanced spintronic and electronic properties in MTe2-GdCl2 (M=Mo, W) heterojunctions

Two-dimensional ferromagnetic heterojunctions with direct bandgaps and high Curie temperatures (TC) are promising candidates for applications in nanoelectronics and spintronics. Here, we design a Mo(W)Te₂-GdCl₂ heterojunction by integrating experimentally synthesized monolayer Mo(W)Te₂ with recently predicted ferromagnetic monolayer GdCl2. Our first-principles calculations reveal that these heterojunctions display a type-II (staggered) band alignment with a narrow direct bandgap ranging from 1.10 to 1.23 eV, using the HSE06 method. We have incorporated spin-orbit coupling and conducted Monte Carlo simulations to precisely estimate the magnetic ground states of these systems. We find that spin-orbit coupling plays a crucial role in the valence band splitting at the K-point in both heterojunctions. The magnetic anisotropy, TC, and optical performance of individual monolayers are enhanced within these heterojunctions. Under compressive strain, the TC of the heterojunctions increases significantly, reaching about 278 K at -7 % strain, due to strengthened super-exchange interactions between Gd-d and Cl-p orbitals and enhanced interlayer charge transfer. In addition, the band alignment shifts from type-II to type-I under -3 % compressive strain, while tensile strain maintains the type-II band alignment. Our findings offer a viable pathway for developing ferromagnetic semiconducting heterojunctions suitable for nanoelectronic and spintronic applications.

Tunable optical properties of BAs/ZnO vdW heterostructure

Stacked heterostructures is an effective strategy for physical property modulation and application of novel two-dimensional materials. In this study, a heterostructure consisting of two-dimensional III-V group hexagonal BAs and monolayer of ZnO is presented. The minimum value of binding and cohesive energies screened the BB’ configuration. Phonon spectra and ab initio molecular dynamics (AIMD) simulations further demonstrated the kinetic and thermodynamic stability of the selected model. Most notably, the formation of the heterostructure greatly improves the optical absorption performance of the monolayer, especially in the infrared (IR) regions. At a compressive strain of −6%, the band alignment shifts from type I to type II, while the bandgap becomes dramatically smaller. Refraction and reflection coefficients in the IR region under compressive strain (−2% and −4%) modulation were enhanced significantly. Our results provide theoretical guidance for the design of high-performance photovoltaic devices and solar cells based on BAs/ZnO heterostructures.

Tunable Ultrafast Charge Transfer across Homojunction Interface.

Charge transfer at heterojunction interfaces is a fundamental process that plays a crucial role in modern electronic and photonic devices. The essence of such charge transfer lies in the band offset, making charge transfer uncommon in a homojunction. Recently, sliding ferroelectricity has been proposed and confirmed in two-dimensional van der Waals stacked materials such as bilayer boron nitride. During the sliding of these layers, the band alignment shifts, creating conditions for charge separation at the interface. We employ ab initio nonadiabatic molecular dynamics simulations to elucidate the excited state carrier dynamics in bilayer boron pnictides. We propose that, akin to ferroelectric polarization flipping, the precise modulation of the distribution of excited state carriers can also be reached by sliding. Our results demonstrate that sliding induces a reversal of the frontier orbital distribution on the upper and lower layers, facilitating a robust interlayer carrier transfer. Notably, the interlayer carrier transfer is more pronounced in boron phosphide than in boron nitride, attributed to strong electron scattering in momentum space in boron nitride. We propose this novel method to manipulate carrier distribution and dynamics in a homojunction exhibiting sliding ferroelectricity, in general, paving a new way for developing advanced electronic and photonic devices.

(Invited) Consideration on Gate Stack Formation Processes of Ultrawide Bandgap Ga2O3 with SiO2 Dielectric Layer

MOSFETs on β-Ga2O3 are expected to be a high-efficient and cost-effective alternative option of high-voltage power devices. Taking account of the reliability and the large conduction-band offset against β-Ga2O3, it would be reasonable to employ SiO2 as the gate dieletric. In this study we investigated the effects of post-deposition annealing (PDA) on SiO2/β-Ga2O3 MOS gate stacks, in terms of the MOS electrical characteristics and the band alignment.β-Ga2O3 (001) wafers with ~2×1016 cm-3 n-type doped epitaxial layers were cleaned in diluted HF solution, and SiO2 films were deposited by electron-beam (EB) evaporation of Si in O2 ambient of ~1×10-2 Pa, followed by PDA at various temperatures from 600 to 1000℃ in either O2 or N2 ambient. Au was evaporated as gate electrode to form MOS capacitors. X-ray photoelectron spectroscopy (XPS) was conducted on the stacks with ~3nm-thick SiO2 for the evaluation of band alignment. Ultraviolet photoelectron spectroscopy (UPS) was also employed to determine the band diagram of β-Ga2O3 (001).Nearly-ideal capacitance-voltage characteristics were obtained for the MOS capacitor fabricated with O2-PDA at 1000℃. The interface state density (Dit) determined by conductance method decreased down to ~1010 cm-3 at the energy level of EC−0.2 eV by PDA at higher temperature. The hysteresis width (ΔVhys) of C-V curves was smaller for the samples annealed at higher temperatures. The flatband voltage (VFB) shift after O2-PDA resulted in VFB close to the ideal value estimated from the physical properties of Au and Ga2O3, suggesting that fixed charge density at the interface would be minimized. However, PDA in N2 at 1000℃ resulted in a negative shift of VFB, which indicates the formation of positive fixed charges in the stack. The beneficial influences of O2-PDA on those characteristics suggest that an oxygen deficiency introduced near the interface is one of the origins of interface defect states. It is noteworthy that Ga3d XPS on the surface of Ga2O3 substrate always shows a tailing in lower binding energy side, which is indicating oxygen deficiency on the surface. The intensity of this lower-binding-energy component reduced significantly when a bare-Ga2O3 substate was annealed in O2, however, it did not decrease efficiently even after O2-PDA when the surface was covered with SiO2. This is probably due to the oxygen rearrangement at SiO2/Ga2O3 interface determined by the difference of material properties of those oxides. This fact suggests that the Ga2O3 surface easily forms oxygen vacancies when it is covered with SiO2. This would be the reason why the formation of interface defect states is not suppressed without O2-PDA.Next the band diagram of β-Ga2O3 (001) substrate was investigated by UPS analysis where the energy level of valence band edge referring to the vacuum level was evaluted from the energy difference between minimum (cut-off) and maximum edges of the obtained kinetic energy spectra of photoelectrons. As a result we found the valence band edge of of β-Ga2O3 (001) was ~8.2 eV below the vacuum level, where the influences of O2 annealing at 1000℃ on the valence band edge energy level was limited to the shift within ~0.1eV. This would tell us the valence band offset between SiO2 and Ga2O3 should be around ~1.1eV, and the conduction band offset between them is to be around 2.8-2.9eV, by taking account of the well-reported SiO2 band diagram and assuming the bandgap of β-Ga2O3 as 4.7eV. On the other hand, the valence band offset estimated from the deconvolution of the XPS valence band spectrum for a ~3nm-thick SiO2/β-Ga2O3 stack from the energy edge difference between the deconvoluted spectra corresponding to SiO2 and Ga2O3, was a few hundreds of mV smaller than the above expected value (~1.1eV). This discrepancy is indicating the formation of an interface dipole layer between SiO2 and Ga2O3 with a pair of nagative and positive charges aligned at the interface to cause a shift in the band alignment. The magnitude of such dipole was indicated to be more significant (~0.5eV) for the stack after PDA at 1000℃, whereas it was less (0.2~0.3eV) after PDA at 600℃.In conclusion, we demonstrated that SiO2/β-Ga2O3 (001) MOS capacitors showed nearly-ideal electrical characteristics with significantly reduced interface defect density and small fixed charge density by applying O2-PDA. The band alignment of SiO2/β-Ga2O3 (001) MOS stack was clarified by photoelectron spectroscopy to confirm a very large conduction band offset of the stack, but an influence of the formation of interface dipole layer between SiO2 and Ga2O3 on the band alighment was also indicated.

Retroperitoneoscopic Simple Nondismembered Pyeloplasty with Da Vinci Si Assistance to Prevent Alignment Shift.

Aims: Retroperitoneoscopic simple nondismembered pyeloplasty (SNDP) with da Vinci Si assistance was developed because of a possible risk for alignment shift after retroperitoneoscopic diamond-shaped bypass pyeloplasty (Diamond-Bypass; DP). Outcomes of SNDP and DP were compared. Materials and Methods: For SNDP, a small longitudinal incision is made on the border of the dilated pelvis and narrowed ureter at the ureteropelvic junction (UPJ). Extending this incision toward the pelvis allows identification of mucosa while maintaining the integrity of surrounding tissues that are so thin and fragile that they will not influence lumen alignment. Data for DP were obtained from a previously published article. Results: For SNDP (n = 3), mean age at surgery was 2.67 years (range: 1-4), mean operative time was 176 minutes. Mean postoperative Society of Fetal Urology (SFU) grades for hydronephrosis were 1.2, 0.7, and 0.6, 1, 2, and 3 months after stent removal, respectively. Postoperative diethylenetriaminepentaacetic acid (DTPA) was normal (n = 3). For DP (n = 5) mean age at surgery was 4.3 years (range: 1-14), mean operative time was 189 minutes. Mean postoperative SFU grades were 2.8, 2.2, and 1.6, respectively. Postoperative DTPA was normal (n = 4) and delayed (n = 1). All SNDP and DP were asymptomatic by 3 months after stent removal. Conclusion: Both SNDP and DP have favorable outcomes. If the UPJ is located at the lowest end of the renal pelvis, SNDP may improve hydronephrosis more quickly.

Rectal deformation management with IGRT in prostate radiotherapy: Can it be managed with rigid alignment alone?

It is challenging to achieve appropriate target coverage of the prostate with Image Guided Radiation Therapy (IGRT) while simultaneously constraining rectal doses within planned values when there is significant variability in rectal filling and shape. We investigated if rectum planning goals can be fulfilled using rigid CBCT-based on-board alignment to account for interfraction rectal deformations. Delivered rectal doses corresponding to prostate alignment ("PR") and anterior rectum alignment ("AR") for 239 daily treatments from 13 patients are reported. Rectal doses were estimated by rigidly mapping the planned dose on the daily CT derived from the daily CBCT according to respective alignment shifts. Rectum V95% (rV95%) was used for analyses. Compared to "PR", "AR" alignment increased rV95% for an average of 34.4% across all patients. rV95% (cc) averaged over all fractions was significant from planning values for 10/13 patients for "PR" and for 9/13 for "AR". 3/13 patients had reproducible anatomy. Of patients with non-reproducible anatomy, three had dosimetrically more favorable, while seven had less favorable anatomies. Most shift differences (82.3%) between the "PR" and "AR" alignments larger than 2mm resulted in rV95% changes larger than 2 cc. Most shift differences (82.2%) of 2mm or less between the "PR" and "AR" alignments resulted in rV95% changes less than 2 cc. The average percentage of fractions among patients in which anterior or posterior shifts for "AR" and "PR" alignment was larger than the PTV margins was 9.1% (0.0%-37.5%) and 1.3% (0%-10%). Rectal deformation and subsequent inconsistent interfraction separation between prostate and rectal wall translate into anatomical changes that cannot always be mitigated with rigid alignment. If systematic differences exist due to a non-reproducible planning anatomy, attempts to restore the planned rectal doses through anterior rectum alignment produce rather small improvements and may result in unacceptable target underdosage.

Examining the Electoral Dynamics: A Comparative Analysis of National Party Performance in the Past Three Indian General Elections

This research explores the complex electoral dynamics of India’s major national parties, focusing on the Bharatiya Janata Party (BJP) and the Indian National Congress (INC) over the last three general elections. The electoral landscape in India is intricately shaped by the interplay of national and regional political entities, as well as the influence of civil society organizations. Central to this dynamic are national parties, which attain their status by meeting specific criteria in the Representation of the People Act, of 1951. Through a detailed analysis of vote share and seat distribution, the study uncovers significant trends and patterns that highlight the evolving electoral landscape. It examines changes in the overall vote share of these parties, identifying factors contributing to their fluctuating performance. Additionally, the research compares the electoral outcomes of the BJP and INC, providing insights into the competitive dynamics between these two dominant political forces. A critical aspect of this study is the investigation of regional variations and their impact on the electoral performance of national parties. The research identifies emerging trends and shifts in regional political alignments by exploring how regional contexts and voter preferences influence election results. Furthermore, the role of civil society organizations is scrutinized to understand their potential as catalysts in shaping electoral outcomes, mobilizing voter bases, and influencing public opinion. By integrating quantitative electoral data with qualitative analysis of political strategies and regional influences, this research aims to comprehensively understand the factors driving the electoral success of major national parties in India. The findings offer valuable insights into the electoral dynamics between national and regional political entities and the broader implications for India’s democratic processes and political stability.

Electronic, optical, and adsorption properties of Li-doped hexagonal boron nitride: a GW approach.

This study employs quasiparticle-corrected DFT calculations to explore the electronic, optical, and surface adsorption properties of Li-doped hexagonal boron nitride (h-BNLi) monolayers. The results reveal that Li doping introduces two defect states into the wide band gap of the monolayer, reducing the band gap from 5.73 eV to 3.72 eV at the K-Γ point of the Brillouin zone. Using the GW approach to incorporate quasiparticle energies demonstrates a distinct advantage over conventional DFT, leading to qualitative shifts in band alignment across the Brillouin zone. Additionally, we identify intragap transitions driven by these defect states, resulting in a significant red shift in the optical gap, decreasing it from 5.73 eV to 1.61 eV in the doped monolayer. Moreover, Li doping enhances the detection of carbon-based gas molecules, raising the surface adsorption energy by -0.42 eV and -0.45 eV compared to the pristine monolayer. These findings hold substantial promise for the application of h-BNLi in electronic, optoelectronic, optical, and sensing devices, effectively subjugating the challenge posed by its wide band gap.

A Novel 2D/3D X-ray Microscopy Alignment and Inspection Solution for Thermocompression Bonding (TCB) in a Highly Integrated Flip Chip Fan-Out Wafer Level Package (FO-WLP)

As packaging drives to extend the capabilities of Moore’s Law via heterogenous integration, numerous bonding technologies have emerged as potential pathways, allowing for integration of both a variety of devices in the lateral space as well as vertical integration of chips via stacking. As vertical integration on interposer becomes more complex due to shrinking CDs and increasing die layers, alignment and shape control in the bonding process becomes critical. Thermocompression bonding (TCB) is particularly well-suited for larger die, where localized reflow allows a better control of chip gap height and tilt throughout the bonding process. TCB systems require both high accuracy and repeatability in all dimensions to provide a reliable system in package. While a 2D system can provide a plan view assessment of a single bond layer between two chips, it falls short in characterizing the critical z-dimension in a highly integrated chip stacking scenario. Therefore a robust solution is needed for both system alignment validation in the x,y plane as well as a capability to explore gap height and bump quality/buried issues in high aspect ratio TSV. This paper will explore an x-ray application of a stacked 15-layer die-to-interposer structure to qualitatively validate overall health of the TSV (bond, pad, fill) via a nondestructive volumetric method as well as quantitatively evaluate stacked die for via/ball/pad alignment to determine overall alignment shift during the bonding process. In the test vehicle for a flip chip FO-WLP process flow first presented by IMEC, a silicon (Si) bridge is utilized to connect the logic and through-package via dies with a bump pitch of 20µm for the logic die interconnect. This is done by carefully aligning the logic dies on the carrier and then placing the through-package dies aligned to the carrier and logic dies. In the final step, a high accuracy placement and stacking TCB tool attaches the Si bridge. To perform an accurate assessment for bump alignment and bond quality, an initial high-resolution 3D x-ray scan is performed on a 1.5mm3 region of interest with over 2,000 individual projections at a 1.4µm voxel resolution with a 4x objective, taking approximately two hours. The dataset is put through a deep-learning algorithm which generates an AI model. This model is then applied to a faster scan of 15 minutes with a 1.4µm voxel resolution for the same field of view (FOV) on a nearby array and the data is collected and processed. To verify alignment of the entire sample, data is collected on the tightest pitch (in this case 20µm) oriented in both the vertical (x) and horizontal (y) plane in the through-silicon via (TSV) region. The z-plane is analyzed and processed by computer vision algorithms, and individual interconnects are then quantified and sorted for solder height (z), width (x,y) and TSV misalignment (deviation from expected center, x1y1 → x2y2). To validate the model, a high-resolution uncorrected 20h scan and a 15min scan based on deep learning are collected for the same region of interest (ROI). The data is comparable. Furthermore, the global misalignment data between both datasets demonstrates similar misalignment propagating through the 15-layer stack.

Collecting the energy of the electromagnetic fields over the infrared band based on the metastructures

Predicated on the surface plasmon polariton, this study proposes the metastructures (MSs) constructed from copper and general dielectric films. The MSs are specifically designed to gather electromagnetic (EM) wave energy over the infrared band on the surface. Evidence illustrates that, when EM waves impinge the surface of the MSs, there is a significant surge in surface energy density, confirmed to be a staggering 2022.90 times higher than that of the ancillary EM waves. This substantial multiplication owes its genesis to the enhanced impedance matching between the MSs and free space. Furthermore, the MSs demonstrate the ability to accurately determine refractive indices ranging from 1 to 1.39, as well as measure hydrogen density spanning from 0 g/cm3 to 0.13 g/cm3. This is achieved through the assessment of absorption peak locations, the intensity of absorption, and the field enhancement factor (FEF) at the peak. The subtle absorption peak experiences a shift in alignment with the changes in refractive indices. The relationship between the peak position and the refractive index demonstrates an exceptional degree of linearity, achieving the R2 value of 1. The values of Q, Sλc, and FOM average at 1437, 1.24 μm·RIU−1, and 682.38 RIU−1, respectively. The study also examines the effects of the incident angle of the external electromagnetic (EM) field and the number of dielectric films. Within a limited range of incident angles, an increase in the angle results in a shift of the absorption peak towards shorter wavelengths. The number of films plays a role in modifying the absorption intensity and the field enhancement factor (FEF) at the peaks. The proposed MSs offer improved energy harvesting capabilities from the surface EM fields. They can also be employed for refractive index detection. Besides, the field enhancement phenomenon provides valuable insights into the adsorption and storage of the hydrogen.

Iran’s Troubled Relations with Afghanistan and Tajikistan: A Compound Alignment Dilemma

ABSTRACT Afghanistan’s reversion to Taliban rule poses severe threats to the Islamic Republic of Iran. Tehran faces a dilemma over how best to respond to these dangers: it could continue to conciliate the Taliban or it could revert to the antagonistic posture it adopted towards Kabul in the 1990s. While each of these strategies can improve Iran’s security situation to some extent, they also entail unintended consequences that exacerbate Iranian vulnerabilities. More importantly, whatever policy Tehran pursues has an impact on Iran’s nascent alignment with Tajikistan, as well as on Tajikistan’s relations with Afghanistan. The fact that Iran’s decision to conciliate the new leadership in Kabul did not prompt Dushanbe to scale back its belligerence towards the Taliban poses a puzzle for Glenn Snyder's concept of the alliance security dilemma. Its solution requires a reconsideration of adversary–ally dynamics that highlights the reciprocal interaction between shifts in inter-state alignment and changes in domestic political contestation.

A Theoretical Investigation of the Structural and Electronic Properties of P/SnBr2 Heterojunctions

In this paper, the structural and electronic properties of P/SnBr2 heterojunctions were investigated using the first-principles calculation method based on the density functional theory (DFT). The band alignment of the P/SnBr2 heterojunction was type I. The bandgap value was 0.71 eV in the DFT calculation. Furthermore, the bandgap of the heterojunction could be efficiently tuned by controlling an electric field and biaxial strain. The bandgap changed linearly with the electric field in a certain range; when the electric field was greater than 0.8 V/Å, the heterojunction was metallic. The bandgap could also be tuned when a biaxial strain was applied. Under tensile or compressive stress, significant effects such as the band alignment shift from type I to type III, and the transition from indirect to direct bandgap occurred. In conclusion, these research findings provide theoretical guidance for designing new heterojunctions based on SnBr2.

The Origin of Dust Polarization in the Orion Bar

The linear polarization of thermal dust emission provides a powerful tool to probe interstellar and circumstellar magnetic fields, because aspherical grains tend to align themselves with magnetic field lines. While the Radiative Alignment Torque (RAT) mechanism provides a theoretical framework for this phenomenon, some aspects of this alignment mechanism still need to be quantitatively tested. One such aspect is the possibility that the reference alignment direction changes from the magnetic field (“B-RAT”) to the radiation field k-vector (“k-RAT”) in areas of strong radiation fields. We investigate this transition toward the Orion Bar PDR, using multiwavelength SOFIA HAWC+ dust polarization observations. The polarization angle maps show that the radiation field direction is on average not the preferred grain alignment axis. We constrain the grain sizes for which the transition from B-RAT to k-RAT occurs in the Orion Bar (grains ≥ 0.1 μm toward the most irradiated locations), and explore the radiatively driven rotational disruption that may take place in the high-radiation environment of the Bar for large grains. While the grains susceptible to rotational disruption should be in suprathermal rotation and aligned with the magnetic field, k-RAT aligned grains would rotate at thermal velocities. We find that the grain size at which the alignment shifts from B-RAT to k-RAT corresponds to grains too large to survive the rotational disruption. Therefore, we expect a large fraction of grains to be aligned at suprathermal rotation with the magnetic field, and to potentially be subject to rotational disruption, depending on their tensile strength.

Facets of Women Leadership in Shakespeare’s Plays: Drawing Parallel and Disconnect in Leadership Styles of Lady Macbeth and Portia

The concept of the leader and the lead is as old as human civilization. Throughout history, the definition of leadership has witnessed paradigm shift in alignment to religious, political, economic and gender power politics. Influx of women in power positions has engaged the minds of the intelligentsia from time to time to question and revisit discourse in leadership. This paper is a literature review-based research, and will deep dive into Shakespeare’s portrayal of powerful women protagonist and their style of leadership with focus on Lady Macbeth from the play Macbeth and Portia from Merchant of Venice. The study will further attempt to explore gender role expectation and gender role disruption to draw parallel and disconnect in their leadership dynamics.

Electrostatic gating dependent multiple band alignments in ferroelectric VS2/Ga2O3 van der Waals heterostructures.

Two-dimensional (2D) van der Waals (vdW) heterostructures with spontaneous intrinsic ferroelectrics play an essential role in ferroelectric memories. Also, the reversal of polarized directions induces band alignment transitions among different types to provide a new path for multifunctional devices. In this work, the structural and electronic properties of 2D VS2/Ga2O3 vdW heterostructures under different polarizations were investigated using first-principles calculations with the vdW correction of the DFT-D2 method. The results reveal that the polarized direction of a 2D Ga2O3 monolayer can cause a distinct band structure reversion from a metal to a semiconductor due to the shift of band alignment induced by the interlayer charge transfer. Moreover, the VS2/P↑ Ga2O3 heterostructures retain type-I and type-II band alignments in the majority and minority channel, respectively, under an external electric field. Interestingly, applying the external electric field for VS2/P↓ Ga2O3 heterostructures can lead to a transition from type-II to type-I in the majority channel, and from type-II to type-III in the minority channel. Our work provides a feasible way to realize 2D VS2/Ga2O3 vdW heterostructures for potential applications in ferroelectric memories and electrostatic gating dependent multiple band alignment devices.

Mapping Pre-Westphalia Europe: Military Alliances, Political Settlements, and Alignments During Armed Conflicts, 1528 to 1648

Abstract This article introduces two new datasets detailing shifts in alliances and alignments in Europe throughout the century prior to the Peace of Westphalia. The datasets identify a list of key actors in the European sphere during this time period and introduce two ways of tracking diplomatic shifts. The Formal Military Alliances and Political Settlements dataset (fmaps) lists all formal treaties and agreements reached between major actors in the European sphere that codified a form of alliance among them and for which a start and end year could be identified. The Alignments During Armed Conflicts Dataset (adacs) lists parties’ alignments during the period’s major armed conflicts. Both datasets were compiled through review of available literature about diplomatic ententes and armed conflicts throughout the period from 1528 to 1648. While the article outlines a few potential weaknesses of the datasets, the authors demonstrate their value for historical and social science research, as well as network analysis.

Engineering Periodic Dinuclear Lanthanide‐Directed Networks Featuring Tunable Energy Level Alignment and Magnetic Anisotropy by Metal Exchange (Small 22/2022)

Lanthanide Multinuclear Networks In article number 2107073, Sofia O. Parreiras, David Écija, and co-workers demonstrate the tuning of the electronic and magnetic properties of dinuclear lanthanide metal–organic networks by metal exchange while preserving the same structural architecture. The exchange between Er and Dy metallic centers leads to a shift in the energy level alignment and allows the tailoring of both the intensity and orientation of magnetic anisotropy.

Improved Surgical Correction Relative to Patient-Specific Ideal Spinopelvic Alignment Reduces Pelvic Nonresponse for Severely Malaligned Adult Spinal Deformity Patients.

Persistent pelvic compensation following adult spinal deformity (ASD) corrective surgery may impair quality of life and result in persistent pathologic lower extremity compensation. Ideal age-specific alignment targets have been proposed to improve surgical outcomes, though it is unclear whether reaching these ideal targets reduces rates of pelvic nonresponse following surgery. Our aim was to assess the relationship between pelvic nonresponse, age-specific alignment, and lower-limb compensation following surgery for ASD. Single-center retrospective cohort study. ASD patients were grouped: those who did not improve in Scoliosis Research Society-Schwab pelvic tilt (PT) modifier (pelvic nonresponders [PNR]), and those who improved (pelvic responders [PR]). Groups were propensity score matched for preoperative PT and assessed for differences in spinal and lower extremity alignment. Rates of pelvic nonresponse were compared across patient groups who were undercorrected, overcorrected, or matched age-specific postoperative alignment targets. A total of 146 surgical ASD patients, 47.9% of whom showed pelvic nonresponse following surgery, were included. After propensity score matching, PNR (N = 29) and PR (N = 29) patients did not differ in demographics, preoperative alignment, or levels fused; however, PNR patients have less preoperative knee flexion (9° vs 14°, P = 0.043). PNR patients had inferior postoperative pelvic incidence and lumbar lordosis (PI-LL) alignment (17° vs 3°) and greater pelvic shift (53 vs 31 mm). PNR and PR patients did not differ in rates of reaching ideal age-specific postoperative alignment for sagittal vertical axis (SVA) or PI-LL, though patients who matched ideal PT had lower rates of PNR (25.0% vs 75.0%). For patients with moderate and severe preoperative SVA, more aggressive correction relative to either ideal postoperative PT or PI-LL was associated with significantly lower rates of pelvic nonresponse (all P < 0.05). For patients with moderate to severe baseline truncal inclination, more aggressive surgical correction relative to ideal age-specific PI-LL was associated with lower rates of pelvic nonresponse. Postoperative alignment targets may need to be adjusted to optimize alignment outcomes for patients with substantial preoperative sagittal deformity. These findings increase our understanding of the poor outcomes that occur despite ideal realignment. Surgical correction of severe global sagittal deformity should be prioritized to mitigate these occurrences.

0217 Is the Timing of the Endogenous Circadian Rhythm of Neurobehavioral Functioning Inherently Task-Dependent?

Abstract Introduction Changes in waking neurobehavioral functioning (NF) over time are governed by homeostatic and circadian processes. It has been reported that peak circadian timing varies inherently between tasks, such that the optimal timing for NF would be task-dependent. Here we investigated this idea with a simulated shift work study protocol followed by a 24h constant routine (CR) protocol to experimentally and statistically separate the circadian from the homeostatic process. Methods N=13 healthy adults (ages 25.5±3.2y; 9 men) completed a 7-day/6-night in-laboratory study. They were randomized to a 3-day simulated day shift condition (n=7) with nighttime sleep (22:00–06:00) or a 3-day simulated night shift condition (n=6) with daytime sleep (10:00–18:00). They then underwent a 24h CR protocol, during which they stayed awake under constant behavioral and environmental conditions and blood was collected at 1–3h intervals for the assessment of dim light melatonin onset (DLMO). During scheduled wakefulness, subjects completed three functionally distinct NF tasks at ~2h intervals: the Karolinska Sleepiness Scale (KSS), Digit Symbol Substitution Test (DSST), and Psychomotor Vigilance Test (PVT). Data from these tasks taken during the CR protocol were analyzed with non-linear mixed-effects regression to separate endogenous circadian effects from the homeostatic process. Results Following simulated night shift, compared to simulated day shift, on average there was a modest, 1.4h (±0.8h SE) delay in DLMO (F1,11=3.68, p=0.082). As such, the simulated night shift condition produced a 10.6h shift in alignment of the homeostatic process relative to the circadian process. Regardless of prior shift condition, the peak of the circadian rhythm effect on NF occurred post-DLMO by 16.8h (±1.0h) for KSS, 15.9h (±1.4h) for DSST, and 18.6h (±1.0h) for PVT, which was not significantly different (F2,9=1.55, p=0.26). Conclusion As proof of principle, we studied three distinct NF assays, and found only small, non-significant differences between them in the timing of underlying circadian rhythmicity. While a larger sample could have yielded statistical significance in our comparison of circadian peak times, the small magnitude of the observed difference does not support the idea of inherent task-dependent differences in the timing of the endogenous circadian rhythm’s influence on NF. Support (If Any) CDMRP W81XWH-16-1-0319 and W81XWH-20-1-0442

0046 Circadian misalignment is associated with Covid-19 infection

IntroductionSleep disturbances are frequently reported in patients infected by Covid-19, but the role of sleep-wake behaviors as a risk factor to contract Covid-19 has up to now poorly been studied. The aim of this study was to explore the relationship between usual sleep-wake behaviors and the risk of Covid-19 infection in a population of subjects suspect of contact or infection with SARS-CoV-2.MethodsCross-sectionnal monocentric study set during a non-confined period in winter 2021. Recruitment took place in a Covid-19 ambulatory screening platform. Subjects between 18 and 45 years old were included whether they were symptomatic or not, healthcare workers or not, in contact with a Covid-19 case or not. They were asked about their usual sleep-wake behaviors. Usual sleep duration and sleep timing were explored during workdays and free days. Circadian misalignment was defined as at least 2 hours shift of circadian alignment (defined as the difference between mid‐sleep during workdays and mid‐sleep during free days, mid sleep as the middle between bedtime and getting up time).ResultsOne thousand eighteen subjects were included in our study (acceptance rate: 10.8%, 39% of men, mean age of 28±8). Habitual mean sleep duration was equivalent in both groups (7h47 vs 7h49, p=0.733). Circadian misalignment greater than 2 hours concerned 33% of subjects in the Covid-19 group versus 20% of the control group (p=0.026). After adjustment on age, gender, BMI and work schedules, subjects presenting a circadian misalignment superior to 2 hours had 2.07 more chances to be tested positive than subjects which respected on identical sleep-wake timing between workdays and free days (OR=2.07, 95%CI= [1.12-3.80], p=0.024).ConclusionAltered sleep not only is present in subjects infected by Covid-19 but could be responsible of a higher change to be infected. Chronobiological impact on immune system and higher chances to be exposed to social contacts could explain our findings which deserve to be confirmed through a future large cohort study. Ultimately regular sleep-wake pattern could constitute a privileged prevention target to fight Covid-19 infection.Support (If Any)