| 1. |
- Fyrner, Timmy
(författare)
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Synthesis of Orthogonally Functionalized Oligosaccharides for Self-assembled Monolayers and as Multimodal Tools in Chemical Biology
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis covers different topics in the field of synthetic organic chemistry combined with the field of surface science and glycobiology.First, the text presents a series of orthogonally protected oligosaccharides (tri-, penta-, and heptasaccharides) of varying length and structures, which are synthesized with the aim of developing novel heterobifunctional biocompatible cross-linkers. Successful conjugation with different chemical handles is also described and used to illustrate the potential implementation of defined carbohydrate based compounds have potential use in biosensing applications. The results of incubation experiments using living cells indicate that the linker is incorporated into cell surfaces and enriched in microdomains.Second, synthesis of various saccharide-terminated alkane thiols immobilized on gold surfaces is reported. The protein adsorption and antifouling characteristics of these surfaces were investigated using model proteins and the common fouling organisms, Ulva linza and Balanus amphitrite.Further, oligo(lactose)-based thiols (di-, tetra-, and hexasaccharides) were synthesized and immobilized on gold nanoparticles to investigate how well these rigid, rod-like oligosaccharides can stabilize such nanoparticles for future use in constructing hybrid nanoparticles.Finally, the thesis describes synthesis of a systematic series of oligo(ethylene) glycols possessing either hydrogen- or methyl-terminated groups. Investigation of the fundamental characteristics of self-assembled monolayers, will give important insights into the design of protein repellant surfaces.
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| 2. |
- Tobieson, Lovisa
(författare)
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Surgically Treated Intracerebral Haemorrhage : Pathophysiology and Clinical Aspects
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mortality and morbidity of intracerebral haemorrhage (ICH) is excessively high, and the case fatality rate has not improved in the last decades. Although surgery for ICH can be life-saving, no positive effect on functional outcome has been found in large cohorts of ICH patients. Increased understanding of the pathophysiology of ICH is needed to develop improved treatment strategies.In 17 ICH patients, paired cerebral microdialysis (CMD) catheters were inserted in the perihaemorrhagic zone (PHZ) and in normal uninjured cortex at time of surgery. Despite normalisation of cerebral blood flow, a persistent metabolic crisis indicative of mitochondrial dysfunction was detected in the PHZ. This metabolic pattern was not observed in the uninjured cortex.CMD was also used to sample proteins for proteomic analysis. A distinct proteome profile that changed over time was found in the PHZ when compared to the seemingly normal, uninjured cortex. However, protein adsorption to CMD membranes, which may interfere with concentration measurements, was substantial.Surgical treatment of 578 ICH patients was analysed in a nation-wide retrospective multi-centre study in Sweden over five years. Patients selected for surgery had similar age, pre-operative level of consciousness and co-morbidity profiles, but ICH volume and the proportion of deep-seated ICH differed among the six neurosurgical centres. Furthermore, there was variability in the post-operative care, including the use and duration of intracranial pressure monitoring, cerebrospinal fluid drainage and mechanical ventilation.In conclusion, the results of this thesis show that:(i) Despite surgical removal of an ICH a metabolic crisis caused by mitochondrial dysfunction, a potential future therapeutic target, persists in the perihaemorrhagic zone.(ii-iii) CMD is a valuable tool in ICH research for sampling novel biomarkers using proteomics, which may aid in the development of improved therapeutic interventions. However, caveats of the technique, such as protein adsorption to the CMD membrane, must be considered.(iv) The nation-wide study illustrates similar clinical features in patients selected for ICH surgery, but substantial variability in ICH volume and location as well as neurocritical care strategies among Swedish neurosurgical centres. Development of refined clinical guidelines may reduce such intercentre variability and lead to improved functional outcome for ICH patients.
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| 3. |
- Vaigur, Peter, 1978-
(författare)
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Samarbete mellan individualister : Reklamproduktion i prat och praktik
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this dissertation lies in the complicated power struggle between supplier and client in knowledge work; the orchestration of the collaboration’s interaction process in a socially and politically relevant way; and the construction, management and maintenance of various images of collaboration – “the asymmetrical”, where one of the parties dominates, and “the symmetrical”, where both parties are on equal footing. The dissertation shows when, where, how and why the orchestration of the interaction process works.In order to answer the research questions, the development of advertising campaigns is examined, creating an example of contemporary work and knowledge work. More particularly, one of Sweden’s larger advertising agencies (Reklambyrån) is examined, when they produce advertising together with three of their clients (Dagligvaran, Kapitalvaran and Klädföretaget). The various types of data material consist of forty-one (41) interviews (or talk about), eighty-six (86) meeting observations (or talk in) and twenty-five (25) shadowings (or practice). The data collection was conducted over a time period of 70 weeks.The dissertation considers knowledge work in general and advertising production in particular as a balancing act between distance and proximity. One creates advertising, but also – or perhaps mainly? – one manages the relationship with both the co-workers and the counterpart in terms of distance and proximity; with the co-workers in terms of individual-collective and with the counterpart in terms of asymmetrical-symmetrical. The examined work is, as implied in the title of the dissertation, a collaboration between “individualists”, in other words people who maintain an arm’s length between themselves and both their co-workers and their counterpart, at least in theory/talk. A theory/talk that is hard to maintain in practice.“The individual” in relation to the co-workers and “the asymmetrical” in relation to the counterpart, in other words the distance, is created for legitimacy reasons, whilst “the collective” in relation to the co-workers and “the symmetrical” in relation to the counterpart, in other words the proximity, is created for efficiency reasons. The advertising, in turn, is created in the stress field between these two forces.
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| 4. |
- Wallenstein, Frederik, 1979-
(författare)
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Muntlighet och minne : Sagatraditionen, kulturhistorien och det kulturella minnets blinda fläck
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation focuses on two distinct areas of study that do not have a predetermined or necessary connection to each other. The first area concerns issues of more immediate relevance to the cultural history of the Icelandic sagas, whereas the second area concerns issues of more general relevance to cultural memory research (Cultural Memory Studies, Kulturelles Gedächtnis) and what the author perceives as a deficiency or “blind spot” in this theory. The latter area, in its turn, falls into two distinct yet related areas of investigation (or critique).In the field of Cultural Memory Studies – finding its most pregnant expression in the work of Jan and Aleida Assmann – there is a consistent and detrimental tendency to underestimate oral tradition. Much of this tendency can be attributed to the Assmann’s abidance by a written/textual norm. Because of this they have had difficulties handling mechanisms of oral transmission, which are often overlooked, misinterpreted, or underestimated. A telling example of this is the discussion of cultural storage and its importance for stability, creativity, and development within a given memory tradition, particularly prominent in the work of Aleida Assmann. Cultural memory theory particularly undervalues oral tradition when it comes to oral prose tradition. That is, the form of oral tradition that has the least in common with written cultural forms of expression. Cultural memory theory thus appears remarkably unable to account for the cultural dynamics of oral traditions as well as having difficulty handling texts with oral origins in a longer diachronic perspective. In the present investigation, this is considered a “blind spot” in the theory of cultural memory.Since this area of study has been largely unexplored within cultural memory research, the empirical basis for the development of such a theory is limited in scope. Nonetheless, the intention in this dissertation is to outline a theory of channels for the transmission of cultural memory in oral prose tradition, and to initiate a critical discussion on how well the existing framework within cultural memory studies is able to accommodate such a theory. What makes these new insights possible is the main empirical material that is taken as a starting point, namely the Icelandic sagas, which will be put to work as an empirical corrective, through the identification of traces of such processes in the saga texts (which are here perceived as a type of orally derived texts).The thesis maintained throughout this dissertation is strictly twofold. The first part is about establishing a fundamental theory of cultural memory processes in oral narrative tradition (“oral prose”). Above all, it is about identifying the oral transmission processes that have established channels for cultural memory transmission. I argue that these processes are partially analogous to those found in written transmission. These processes also entail certain types of stabilizing contextual factors that may be relevant in this context. The second part is about supplementing the memory theory’s view of cultural transmission and reproduction with less “fossilized” and more “living” types of transmission. This supplementary aim, in turn, requires a thorough discussion of several central terms in cultural memory theory. As a result, such an analysis has to involve the establishment of a diachronic cultural historical perspective on the saga literature. This ambition is part of a broader and somewhat loosely formulated goal of the dissertation.
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| 5. |
- Björck, Fredrik, 1974-
(författare)
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Warfarin treatment quality in stroke prevention
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundIschemic stroke is a serious condition often associated to presence of atrial fibrillation (AF). Use of anticoagulants for AF patients greatly reduces the risk of stroke. Warfarin is the most commonly used anticoagulant in Sweden. The aim of this thesis was to study the impact of warfarin treatment quality in Swedish stroke prevention.MethodsStudy I, II and IV were relatively large multicentre, retrospective, cohort studies based on Swedish registries, especially AuriculA, a quality register for AF and anticoagulation. Background data as well as bleeding and thromboembolic complications were retrieved from the National Patient Register. The Cause of Death Register was used in study II and IV. The Swedish Prescribed Drug Register was used in study IV, for data on concomitant acetylsalicylic acid (ASA) use. Study period was January 1, 2006, to December 31, 2011. Study III enrolled all warfarin treated AF patients in Sundsvall, registered in AuriculA on January 1, 2010. This smaller cohort was followed until discontinuation or study-stop December 31, 2013. All used data were collected from each patient’s medical record.ResultsThe annual risk of major bleedings and thromboembolic events for warfarin treated patients, including all different indications for warfarin, was relatively low (2.24% and 2.66%), with incidence of intracranial bleeding of 0.37% per treatment year. The overall mean time in therapeutic range (TTR) was 76.5%. Patients started on warfarin due to AF had a mean TTR of 68.6%, with an annual risk of major bleeding and thromboembolic events of 2.23% and 2.95%, and with 0.44% annual risk of intracranial bleeding. No significant differences in overall complications were found when comparing treatment monitored in anticoagulation clinics (ACC) with treatment monitored in primary health care centers (PHCC). There were significantly increased risk of both overall major bleedings and thromboembolic events for those warfarin treated AF patients receiving additional ASA treatment, having individual TTR (iTTR) below 70%, or having high international normalized ratio (INR) variability. AF patients with low INR variability had generally lower complication rates, compared with patients with high INR variability. There were however no alteration on cumulative incidence of complications due to INR variability, for AF patients with iTTR ≥70%. The overall proportion of persistence to warfarin treatment for stroke patients with AF was found to be 0.69 after 2 years treatment and 0.47 after 5 years. Stroke patients with diagnosed dementia at baseline were more than two-times likely of discontinuing warfarin than others. Excessive alcohol use, chronic obstructive pulmonary disease, cancer and chronic heart failure were baseline diagnoses each associated with over 20% increased risk of treatment discontinuation. Lower persistence to treatment was linked to increasing start-age and CHA2DS2-VASc scores. As documented reasons for warfarin treatment discontinuation in AF patients, we found regained sinus rhythm as the most common addressed cause (31.2%), followed by problematic monitoring and bleedings. We estimated that only half (49.5%) of the treatment discontinuations were clinically well motivated.ConclusionsQuality of Swedish warfarin treatment in initiated stroke prevention is high, with generally low rates of complications and high TTRs, no matter treatment in ACC or PHCC, including high long time persistence to warfarin in secondary stroke prevention. For better outcome in future warfarin stroke prophylactic treatment clinicians should aim for iTTRs above 70%, avoid additional ASA therapy, support fragile patients like those with excessive alcohol use and dementia, and base decisions on treatment discontinuations on solid medical arguments.
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| 6. |
- Börjeson, Love, 1973-
(författare)
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Förtroendets Organiseringsmetod : samarbete, svek och dilemman
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Firms tend to engage in interorganizational relationships (IORs) to an increasingly large extent. IORs are however problematic. On one hand, they entail expectations of continued possibilities. On the other hand, they entail expectations of complete explicitness – business partners simply expect intentions to be transparent and fixed. Co-workers in IORs manage these expectations with trust: in the context of IORs, trust is both a promise of continued possibilities and explicitness. Continued possibilities require changeable intentions however, making explicitness hard to maintain. The given promise is consequently very hard to keep, and the result is accusations of betrayal. The management method of trust is comprised by dilemmas originating from a complex interplay between strong ideas about what to (and not to) do and the dynamics of IORs. This could be described as an interplay between ideology, cooperative situations and dilemmas of practice. Ideology is investigated using corpus linguistics and functional grammar applied on concordances extracted from academic articles about Trust and the contrasting terms Control and Betrayal. Cooperative situations are investigated using correspondence analysis applied on an indexed interview material. Underlying interviews concern IORs, and informants come from a broad sample reflecting different types of firms, industries and professions. Dilemmas of practice, finally, are represented by in-depth interviews with individuals whom possess rich experience of IORs. The interviews are transcribed in detail and analyzed using functional grammar. Results show that IORs are profoundly dilemmatic and that co-workers use trust as a mean to bridge the dilemmas of IORs. Result also reveals that dilemmas of IORs have an ambiguous quality; dilemmas are not just a problem that needs to be handled, but to an equal extent a resource that can be used for deliberation and decision. In the management method of trust, dilemmas are as inevitable as they are indispensable.
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| 7. |
- Grzymala-Lubanski, Bartosz, 1980-
(författare)
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Anticoagulation treatment in patients with a mechanical heart valve
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundEvery year about 2,500 patients in Sweden undergo surgery for heart valve disease, primarily in the aortic valve. In contrast to the mitral valve, which can be repaired in 70% of the cases, the aortic valve is normally replaced by a mechanical or biological prosthesis. A mechanical heart valve (MHV) necessitates lifelong anticoagulation treatment with a vitamin K antagonist, most commonly warfarin, due to the high thrombogenicity of the prosthesis. The quality of the warfarin treatment is crucial in these patients. Compared to other countries, treatment quality in Sweden is very high; nonetheless, there is always room for improvement. One of the ways to achieve this improvement is to implement computerized dosing assistance. Treatment recommendations for anticoagulation intensity are based on few and old studies, making these recommendations uncertain. There is therefore a need for studies designed to establish the appropriate level of anticoagulation therapy.AimThe aim of these studies was to investigate the efficacy and safety of anticoagulation treatment among patients with mechanical heart valve prostheses in Sweden; to assess whether computerized dosing can increase the treatment quality; to investigate the influence of the treatment quality, measured by Time in Therapeutic Range (TTR) and INR variability, on the risk of complications and, finally, to establish the optimal intensity of anticoagulation treatment in this group of patients.MethodsData were obtained from AuriculA – a national quality registry established in 2006, which currently includes approximately 50% of all patients treated with oral anticoagulation in Sweden.Study II used only data from AuriculA. 769,933 warfarin-dosing suggestions proposed by the dosing algorithm in AuriculA were analysed. Accepted dose suggestions (590,939) were compared with 178,994 manually-changed doses in regard to the resultant INR value, measured as mean error (deviation from target INR) and hit rate (number of INR samples within the target range 2-3).In study III, AuriculA was used to identify patients in Sundsvall and Malmö in the period 2008 – 2011 who were receiving warfarin for a mechanical heart valve prosthesis, as well as to retrieve their INR data. Data on background characteristics and bleedings or thromboembolic complications were manually retrieved from medical records by two investigators. A total of 534 patients with mechanical heart valve prostheses were divided into quartiles based on TTR and were compared regarding the risk of complications.For Studies I and IV, data from AuriculA were merged with the Swedish National Patient Register, SWEDEHEART/ Heart surgery, and the Swedish Cause of Death Register, comprising in total 77,423 patients on warfarin with 217,804 treatment years. Every treatment period registered in AuriculA was given an individual identification number. During the study period a patient could have any number of treatment periods. The number of complications in total and in different patient groups within the study population was investigated. Complications were defined by ICD-10 codes. Major bleeding was defined as an event necessitating hospital treatment and given a discharge diagnosis with one of the ICD-10 codes reflecting bleeding, as listed in the Appendix. Bleeding events were divided into intracranial, gastrointestinal and other bleedings. Thromboembolic complications consist of venous events (deep vein thrombosis, pulmonary embolism, venous stroke) or arterial events (stroke, TIA, acute myocardial infarction, peripheral arterial embolism).Data were analysed using both simple, descriptive statistical methods and various tests such as Mann-Whitney (or two sample Wilcoxon), T-test, Chi 2 test, ANOVA, multivariate analysis with logistic regression and survival analysis with Cox Regression with proportional hazard assumption.ResultsTreatment quality Mean TTR among all patients in Study I was 76.5% whereas patients with mechanical heart valve prostheses had a TTR of 74.5%. The annual incidence of major bleeding or thromboembolic events among all patients was 2.24% and 2.65%, respectively. The incidence of intracranial bleeding was 0.37% per year in the general population and 0.51% among patients with mechanical heart valve prostheses, who also had a higher bleeding rate in total (3.37% per year).Both the mean and median errors were smaller (0.44 vs. 0.48 and 0.3 vs. 0.4, respectively) and the hit rate was higher (0.72 vs. 0.67) when the dose suggested by the algorithm was accepted, compared to when it was manually changed.TTR In Study III there was no significant difference in the risk of thromboembolism regardless of TTR level. Risk of bleeding in quartiles I and II was more than two times higher than in the quartile with TTR >82.9.In Study IV, lower TTR (≤70%) was associated with a significantly higher rate of complications when compared with TTR >70%. Bleeding risk was higher in the group with lower TTR (HR=2.43, CI 2.02-2.89, p<0.001). After dividing patients into TTR quartiles, the rate of complications in total was significantly higher in quartiles I to III compared with quartile IV, which had the highest TTR. Risk of thromboembolism, major bleeding and death was higher in the first and second quartile compared to the quartile with the highest TTR.INR variability Higher INR variability above mean (≥0.40) was related to a higher rate of complications compared with lower INR variability (<0.40) as shown in Study IV. Bleeding risk was higher in the group with INR variability ≥0.40 (HR = 2.15, CI 1.75-2.61, p<0.001).Comparison of quartile IV, which had the lowest INR variability, with the other three revealed that quartiles I and II, which had the highest INR variability, had significantly worse outcomes for all complications except for thromboembolic events, plus also death in quartile II.TTR and INR variability combined High variability and low TTR combined was associated with a higher risk of bleedings (HR 2.50, CI 1.99-3.15), death (3.34, CI 2.62-4-27) and thrombosis (1.55, CI 1.21-1.99) compared to the best group.Level of anticoagulation Higher warfarin treatment intensity (mean INR 2.8-3.2 vs. 2.2-2.7) was associated with a higher rate of bleedings (HR 1.29, CI 1.06-1.58), death (1.73, CI 1.38-2.16) and complications in total (1.24, CI 1.06-1.41) after adjustment for MHV position, age and comorbidity.ConclusionWarfarin treatment quality is crucial for patients with mechanical heart valve prostheses. Computerized dosing assistance could help maintain high warfarin treatment quality.Well-managed treatment with TTR ≥70% and INR variability below mean <0.40 is associated with a lower risk of serious complications compared with a lower TTR and higher INR variability.No benefit of higher warfarin treatment intensity was found for any valve type or position.
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| 8. |
- Hertz, Erik, 1956-
(författare)
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Methodologies for Approximation of Unary Functions and Their Implementation in Hardware
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Applications in computer graphics, digital signal processing, communication systems, robotics, astrophysics, fluid physics and many other areas have evolved to become very computation intensive. Algorithms are becoming increasingly complex and require higher accuracy in the computations. In addition, software solutions for these applications are in many cases not sufficient in terms of performance. A hardware implementation is therefore needed. A recurring bottleneck in the algorithms is the performance of the approximations of unary functions, such as trigonometric functions, logarithms and the square root, as well as binary functions such as division. The challenge is therefore to develop a methodology for the implementation of approximations of unary functions in hardware that can cope with the growing requirements. The methodology is required to result in fast execution time, low complexity basic operations that are simple to implement in hardware, and – sincemany applications are battery powered – low power consumption. To ensure appropriate performance of the entire computation in which the approximation is a part, the characteristics and distribution of the approximation error are also things that must be possible to manage. The new approximation methodologies presented in this thesis are of the type that aims to reduce the sizes of the look-up tables by the use of auxiliary functions. They are founded on a synthesis of parabolic functions by multiplication – instead of addition, which is the most common. Three approximation methodologies have been developed; the two last being further developments of the first. For some functions, such as roots, inverse and inverse roots, a straightforward solution with an approximation is not manageable. Since these functions are frequent in many computation intensive algorithms, it is necessary to find very efficient implementations of these functions. New methods for this are also presented in this thesis. They are all founded on working in a floating-point format, and, for the roots functions, a change of number base is also used. The transformations not only enable simpler solutions but also increased accuracy, since the approximation algorithm is performed on a mantissa of limited range. Tools for error analysis have been developed as well. The characteristics and distribution of the approximation error in the new methodologies are presented and compared with existing state-of-the-art methods such as CORDIC. The verification and evaluation of the solutions have to a large extent been made as comparative ASIC implementations with other approximation methods, separately or embedded in algorithms. As an example, an implementation of the logarithm made using the third methodology developed, Harmonized Parabolic Synthesis (HPS), is compared with an implementation using the CORDIC algorithm. Both implementations are designed to provide 15-bit resolution. The design implemented using HPS performs 12 times better than the CORDIC implementation in terms of throughput. In terms of energy consumption, the new methodology consumes 96% less. The chip area is 60% smaller than for the CORDIC algorithm. In summary, the new approximation methodologies presented are found to well meet the demanding requirements that exist in this area.
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| 9. |
- Hober, Sophia, Professor, 1965-, et al.
(författare)
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Systematic evaluation of SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay
- 2021
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Ingår i: Clinical & Translational Immunology. - : Wiley. - 2050-0068. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The COVID-19 pandemic poses an immense need for accurate, sensitive and high-throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high-throughput multiplex bead-based serological assay. Methods. More than 100 representations of SARS-CoV-2 proteins were included for initial evaluation, including antigens produced in bacterial and mammalian hosts as well as synthetic peptides. The five best-performing antigens, three representing the spike glycoprotein and two representing the nucleocapsid protein, were further evaluated for detection of IgG antibodies in samples from 331 COVID-19 patients and convalescents, and in 2090 negative controls sampled before 2020. Results. Three antigens were finally selected, represented by a soluble trimeric form and the S1-domain of the spike glycoprotein as well as by the C-terminal domain of the nucleocapsid. The sensitivity for these three antigens individually was found to be 99.7%, 99.1% and 99.7%, and the specificity was found to be 98.1%, 98.7% and 95.7%. The best assay performance was although achieved when utilising two antigens in combination, enabling a sensitivity of up to 99.7% combined with a specificity of 100%. Requiring any two of the three antigens resulted in a sensitivity of 99.7% and a specificity of 99.4%. Conclusion. These observations demonstrate that a serological test based on a combination of several SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.
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| 10. |
- Johansson, Anders, 1975-
(författare)
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Context dependent adaptation of biting behavior in human
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this thesis was to study an action that humans perform regularly, namely, to hold a morsel between the teeth and split it into smaller pieces. Three different issues related to this biting behavior were addressed: (1) the effect of reduced periodontal tissues on food holding and splitting behavior; (2) the behavioral consequences of performing different bite tasks with different functional requirements, i.e., to split a peanut half resting on a piece of chocolate or to split both the peanut and the chocolate; and (3) the reflex modulations resulting from such a change in the intended bite action. The main conclusions from the experimental studies were the following:First, periodontitis, an inflammatory disease that destroys the periodontal ligaments and the embedded periodontal mechanoreceptors, causes significant impairments in the masticatory ability: the manipulative bite forces when holding a morsel are elevated compared to a matched control population and the bite force development prior to food split is altered. These changes are likely due to a combination of reduced sensory information from the damaged ligaments and to changes in the bite strategy secondary to the unstable oral situation.Second, people exploit the anatomy of jaw-closing muscles to regulate the amount of bite force that dissipates following a sudden unloading of the jaw. Such control is necessary because without mechanisms that quickly halt jaw-closing movements after sudden unloading, the impact forces when the teeth collide could otherwise damage both the teeth and related soft tissues. Splitting a piece of chocolate, for instance, regularly requires >100N of bite force and the jaws collide within 5 ms of a split. On the other hand, when biting through heterogeneous food, the bite force needs to be kept high until the whole morsel is split. The required regulation is achieved by differentially engaging parts of the masseter muscles along the anteroposterior axis of the jaw to exploit differences between muscle portions in their bite force generating capacity and muscle shortening velocity.Finally, the reflex evoked by suddenly unloading the jaw—apparent only after the initial bite force dissipation—is modulated according to the bite intention. That is, when the intention is to bite through food items with multiple layers, the reflex response in the jaw opening muscles following a split is small, thus minimizing the bite force reduction. In contrast, when the intention is to rapidly decrease the bite force once a split has occurred, the reflex response is high. This pattern of reflex modulation is functionally beneficial when biting through heterogeneous food in a smooth manner.The presented studies show the significance of integrating cognitive, physiological and anatomical aspects when attempting to understand human masticatory control.
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