Role of quantum coherence in shaping the line shape of an exciton interacting with a spatially and temporally correlated bath.

Kubo's fluctuation theory of line shape forms the backbone of our understanding of optical and vibrational line shapes, through such concepts as static heterogeneity and motional narrowing. However, the theory does not properly address the effects of quantum coherences on optical line shape, especially in extended systems where a large number of eigenstates are present. In this work, we study the line shape of an exciton in a one-dimensional lattice consisting of regularly placed and equally separated optical two level systems. We consider both linear array and cyclic ring systems of different sizes. Detailed analytical calculations of line shape have been carried out by using Kubo's stochastic Liouville equation (SLE). We make use of the observation that in the site representation, the Hamiltonian of our system with constant off-diagonal coupling J is a tridiagonal Toeplitz matrix (TDTM) whose eigenvalues and eigenfunctions are known analytically. This identification is particularly useful for long chains where the eigenvalues of TDTM help understanding crossover between static and fast modulation limits. We summarize the new results as follows. (i) In the slow modulation limit when the bath correlation time is large, the effects of spatial correlation are not negligible. Here the line shape is broadened and the number of peaks increases beyond the ones obtained from TDTM (constant off-diagonal coupling element J and no fluctuation). (ii) However, in the fast modulation limit when the bath correlation time is small, the spatial correlation is less important. In this limit, the line shape shows motional narrowing with peaks at the values predicted by TDTM (constant J and no fluctuation). (iii) Importantly, we find that the line shape can capture that quantum coherence affects in the two limits differently. (iv) In addition to linear chains of two level systems, we also consider a cyclic tetramer. The cyclic polymers can be designed for experimental verification. (v) We also build a connection between line shape and population transfer dynamics. In the fast modulation limit, both the line shape and the population relaxation, for both correlated and uncorrelated bath, show similar behavior. However, in slow modulation limit, they show profoundly different behavior. (vi) This study explains the unique role of the rate of fluctuation (inverse of the bath correlation time) in the sustenance and propagation of coherence. We also examine the effects of off-diagonal fluctuation in spectral line shape. Finally, we use Tanimura-Kubo formalism to derive a set of coupled equations to include temperature effects (partly neglected in the SLE employed here) and effects of vibrational mode in energy transfer dynamics.

Anomalous dimensionality dependence of diffusion in a rugged energy landscape: How pathological is one dimension?

Diffusion in one dimensional rugged energy landscape (REL) is predicted to be pathologically different (from any higher dimension) with a much larger chance of encountering broken ergodicity [D. L. Stein and C. M. Newman, AIP Conf. Proc. 1479, 620 (2012)]. However, no quantitative study of this difference has been reported, despite the prevalence of multidimensional physical models in the literature (like a high dimensional funnel guiding protein folding/unfolding). Paradoxically, some theoretical studies of these phenomena still employ a one dimensional diffusion description for analytical tractability. We explore the dimensionality dependent diffusion on REL by carrying out an effective medium approximation based analytical calculations and compare them with the available computer simulation results. We find that at an intermediate level of ruggedness (assumed to have a Gaussian distribution), where diffusion is well-defined, the value of the effective diffusion coefficient depends on dimensionality and changes (increases) by several factors (∼5-10) in going from 1d to 2d. In contrast, the changes in subsequent transitions (like 2d to 3d and 3d to 4d and so on) are far more modest, of the order of 10-20% only. When ruggedness is given by random traps with an exponential distribution of barrier heights, the mean square displacement (MSD) is sub-diffusive (a well-known result), but the growth of MSD is described by different exponents in one and higher dimensions. The reason for such strong ruggedness induced retardation in the case of one dimensional REL is discussed. We also discuss the special limiting case of infinite dimension (d = ∞) where the effective medium approximation becomes exact and where theoretical results become simple. We discuss, for the first time, the role of spatial correlation in the landscape on diffusion of a random walker.

Surgical Management of a Pediatric Cuboid Nutcracker Fracture: A Case Report.

CASE: Cuboid impaction fractures (nutcracker fractures) result from high-energy trauma and are exceedingly rare in children. We present a case of an 8-year-old boy who sustained a comminuted cuboid nutcracker fracture after a fall from height. The patient underwent open reduction and internal fixation with a locking plate. At 1 year postoperatively, lateral column length and articular congruency were maintained, and the patient return to full function and activity. CONCLUSION: Cuboid nutcracker fractures in children are rare and can be successfully treated with open reduction and internal fixation with locking plates, with excellent radiographic and functional outcomes.

Paecilomyces lilacinus olecranon bursitis in an immunocompromised host: case report and review.

Paecilomyces lilacinus is a little-known mold that causes rare cases of invasive infections in humans regardless of their immune status. We present a unique case in an immunocompromised host with olecranon bursitis because of multidrug-resistant P. lilacinus treated with systemic ketoconazole therapy and surgical debridement. Recognition of this fungus is difficult initially because of its appearance, which can be confused with that of other fungi. Once this organism has been identified, it is recommended that antifungal susceptibility testing be obtained to guide appropriate therapy. Combination of therapeutic modalities requires case-by-case assessment. Surgical debridement and removal of prosthesis may be indicated. Although P. lilacinus can be a laboratory contaminant, in our case, causation was established as the organism grew in repeated cultures, sufficient to confirm a fungal origin for his bursitis.

The effect of an orthopedic trauma room on after-hours surgery at a level one trauma center.

PURPOSE: The purpose of this study is to examine the effect of establishing a dedicated operating room for unscheduled orthopedic cases and to evaluate a group of patients with isolated femur fractures. The frequency of after-hours surgery and the impact of patients who present with acute orthopedic injuries are reviewed. METHODS: A retrospective review of all orthopedic cases from the operating room scheduling system at a level-one trauma center was undertaken from October 2003 to September 2005. Before October 2004, unscheduled cases were placed on a shared add-on list, and no special priority was given to orthopedic cases. Additionally, a subset of adult patients with isolated femoral shaft fractures was identified to evaluate time from admission to surgery, operative time, frequency of transfer of care between surgeons, and total length of hospital stay. RESULTS: The number of orthopedic cases was 1799 in fiscal year 2004 (FY04) and 2046 in FY05, an increase of 14%. Overall, the hospital experienced an increase in level-one trauma activations from 1450 in FY04 to 1580 in FY05 (8.2%), and an increase in the number operative trauma cases from 447 to 494 (9.5%). Cases after 7:00 pm declined from 197 in FY04 to 165 in FY05, a decrease of 16%. Cases between midnight and 7:00 am declined from 63 in FY04 to 35 in FY05, a decrease of 44%. For the subset of femur fracture patients, transfer of care to another operating surgeon occurred 4.5 times more frequently. The median delay between admission and surgery increased from 5.7 hours to 10.9 hours. Median case duration increased from 106 to 127 minutes. CONCLUSIONS: It is possible to dramatically decrease the occurrence of after-hours orthopedic surgery in a level-one trauma center through the use of a dedicated room for unscheduled orthopedic trauma cases. Benefits include less frequent activation of after-hours operating room resources, fewer disruptions to the OR schedule and office hours, and more frequent fracture care by orthopedic traumatologists. The impact of a longer delay between admission and surgical treatment and more frequent transfer of care between surgeons deserves further evaluation.

Lateral Subtalar Dislocation with Tarsometatarsal Dislocation: A Case Report of a Rare Injury.

Dislocation of the fourth and fifth tarsometatarsal joints in conjunction with lateral subtalar dislocation is a rare occurrence. Little is known about the mechanism of injury, the appropriate treatment for this condition, and its ultimate prognosis. In this report, we describe this atypical presentation in a middle aged, otherwise healthy male who sustained a trivial twisting injury to the ankle when he slipped and fell on ice. Open reduction and K-wire fixation were necessary to affix the lateral tarsometatarsal and talonavicular joints. At one year postoperatively, he was able to return to his preinjury occupation with mild to moderate pain with prolonged walking. His Foot and Ankle Disability Index and American Orthopaedic Foot and Ankle Society scores were 64 and 65 points, respectively. Surgical intervention resulted in a stable plantigrade foot; however, the patient had early radiographic evidence of posttraumatic arthritis in the midfoot joints at one-year follow-up.

Reconstructive Shelf Arthroplasty as a Salvage Procedure for Complex Fifth Tarsometatarsal Joint Complex Injuries: A Case Review and Discussion.

High-energy cuboid fractures are rare injuries that are commonly associated with other midfoot trauma. With displacement, operative intervention is critical to restore articular congruity and the length of the lateral column. Failure to achieve this predisposes patients to posttraumatic arthritis and deformity, often necessitating secondary procedures. Although primary open reduction and internal fixation is the standard of care for these injuries, at times the traditional principles of fracture fixation cannot be applied to cuboid fractures. We describe the case of a 45-year-old woman who underwent a reconstructive shelf arthroplasty of the cuboid and fifth tarsometatarsal joint for a severe injury to the lateral column of the midfoot.

Dedicated orthopaedic operating rooms: beneficial to patients and providers alike.

OBJECTIVE: Dedicated orthopaedic operating rooms (DOORs) are increasingly popular solutions to reducing after-hours procedures, physician fatigue, and elective schedule disruptions. Although the benefits to surgeons are well understood, there are comparatively few studies that explore the effects of DOORs on patient care. We compared treatments and outcomes for all consecutive patients with femoral neck fractures, 4 years before and 4 years after implementation of a DOOR-based schedule. DESIGN: Retrospective case-control study. SETTING: Level 1 academic trauma center. PATIENTS: A total of 111 consecutive trauma patients undergoing surgical management of isolated OTA group 31-B femoral neck fractures. INTERVENTION: Based on individual patient factors and fracture characteristics, patients were managed with either hemiarthroplasty or open reduction internal fixation (ORIF). MAIN OUTCOME MEASURES: Surgical timing, intervention type, perioperative complications, and postoperative length of stay. RESULTS: Retrospective analysis revealed a significant decrease in after-hour surgery (4 PM-7:30 AM) for all femoral neck fractures (66.7%-19.3%; P < 0.001). No significant differences were found between the rates of arthroplasty versus those of open reduction internal fixation. Patients undergoing surgical treatment for femoral neck fractures after DOOR suffered significantly fewer morbidities, including significantly decreased rates of postoperative intensive care unit admissions, stroke, infections, and myocardial infarction or congestive heart failure exacerbations. We also observed a significant decrease in postoperative mortality (5.6% pre-DOOR vs. 0% post-DOOR; P = 0.04). Patients undergoing hemiarthroplasty experienced a significant shorter hospitalization (14.5 days pre-DOOR vs. 9.9 days post-DOOR; P = 0.04). CONCLUSIONS: In our experience, a weekday DOOR is closely associated with improvements in both patient safety and outcomes. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Preliminary trauma radiographs misrepresent pubic diastasis injuries.

The goal of this study was to evaluate the role of portable primary trauma survey radiographs in the evaluation and management of anteroposterior (AP) compression pelvic injuries. A retrospective analysis was conducted at a level I academic trauma center. Twenty-seven adults with AP compressive class pelvic ring injuries who received both portable pelvic radiographs and pelvic computed tomography (CT) imaging in an unbound pelvic state were included. Three orthopedic surgeons performed independent measurements of diastasis on portable pelvic radiographs and coronal pelvic CT reconstructions. Measurement techniques were standardized among observers and were repeated after 8 weeks to assess intraobserver reliability. Nonoperative vs operative treatments were correlated with the initial magnitude of pelvic injury on CT and portable radiographic images. Independent measurements of diastasis on both radiographs and CT scans showed excellent intraobserver reliability (average correlation coefficient, 0.986) and interobserver reliability (average correlation coefficient, 0.979). Compared with diastasis measurements on CT scans, portable pelvic radiographs overestimated diastasis by an average of 49%, or 12.6 mm (P<.0001; 95% confidence interval, 9.6-15.6). Portable pelvic films were less precise than standard pelvic radiographs in measuring the size of femoral head controls (R(2)=0.919 vs 0.759; P=.004). In 12 of the 27 patients evaluated, radiographic indications for operative pelvic fixation were met by portable radiographs but not CT scans, and 11 of these patients ultimately underwent operative fixation. Portable AP pelvic radiographs may distort and exaggerate pelvic bony injuries, especially those involving anterior pelvic structures. Surgeons should use caution when making management decisions based on preliminary portable pelvic radiographs.

An atypical presentation of heterotopic ossification following pelvic ring injury.

Disruption of the pelvic ring is associated with great morbidity and mortality. The high-energy blunt trauma that often leads to these injuries is also responsible for the head, chest, spine, extremity, and genitourinary trauma seen concurrently. Urethral and bladder injuries have been reported in up to 25% of patients with pelvic fractures and can lead to a plethora of urogenital problems. Heterotopic ossification of the penis, presenting as erectile dysfunction, has never been described as a complication of pelvic ring injury. We present the first case of this type of heterotopic ossification, in a 46-year-old male who sustained an anteroposterior compression type II injury with no evidence of genitourinary tract damage.

Hardware complications in scoliosis surgery.

BACKGROUND: Scoliosis surgery has undergone a dramatic evolution over the past 20 years with the advent of new surgical techniques and sophisticated instrumentation. Surgeons have realized scoliosis is a complex multiplanar deformity that requires thorough knowledge of spinal anatomy and pathophysiology in order to manage patients afflicted by it. Nonoperative modalities such as bracing and casting still play roles in the treatment of scoliosis; however, it is the operative treatment that has revolutionized the treatment of this deformity that affects millions worldwide. As part of the evolution of scoliosis surgery, newer implants have resulted in improved outcomes with respect to deformity correction, reliability of fixation, and paucity of complications. Each technique and implant has its own set of unique complications, and the surgeon must appreciate these when planning surgery. MATERIALS AND METHODS: Various surgical techniques and types of instrumentation typically used in scoliosis surgery are briefly discussed. Though scoliosis surgery is associated with a wide variety of complications, only those that directly involve the hardware are discussed. The current literature is reviewed and several illustrative cases of patients treated for scoliosis at the Connecticut Children's Medical Center and the Newington Children's Hospital in Connecticut are briefly presented. CONCLUSION: Spine surgeons and radiologists should be familiar with the different types of instrumentation in the treatment of scoliosis. Furthermore, they should recognize the clinical and roentgenographic signs of hardware failure as part of prompt and effective treatment of such complications.

Treatment of complex proximal humeral fractures with minimally invasive fixation of the humeral head combined with flexible intramedullary wire fixation - introduction of a new treatment concept.

The treatment of three- or 4-part proximal humerus fractures is still a matter of scientific discussion. The following study presents the results of a combined procedure using limited invasive fixation techniques for reconstruction of the humerus head and retrograde intramedullary wiring with elastic nails for the treatment of displaced three- or 4-part fractures. A prospective study of 24 patients with 3-part and 4-part fractures was performed from September 1995 to December 1998. Combined biologic fixation for reconstruction of the humerus head, including intramedullary wiring, was utilized. Fracture reduction was performed in an open soft-tissue-preserving technique through a limited lateral approach. Fixation of the head fragments was performed using screw and/or cerclage wire fixation. The reconstructed humerus head was stabilized to the shaft with intramedullary wires, with retrograde insertion 2 cm above the olecranon fossa. Supportive fixation of the head fragments was achieved using fully threaded cancellous screws. At the 1-year postoperative follow-up, 40% of the 18 patients had excellent results using the Neer and Constant score. Forty-five percent had satisfactory and 15% unsatisfactory results. The initial results of this study reveal that a combination of limited internal fixation of the humerus head and retrograde elastic intramedullary wiring provide stable fixation with limited soft-tissue destruction. This approach has been shown to be especially useful for the combined treatment of three- or four-part fractures of the humeral head.